BIO 205 : Final Exam

This set of flashcards covers key terms and concepts from the study guide for the nursing final exam, assisting in the review of important vocabulary and definitions.

Vegetative cell

✨ Definition

Active, living form of a bacterium that is growing, metabolizing, and reproducing

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🔑 Key Concept

• This is the normal state of bacteria

• Metabolically active → uses nutrients and makes energy

• Reproduces by binary fission

• Sensitive to heat, chemicals, and antibiotics

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🔄 Relationship to Spores

• When conditions are unfavorable (no nutrients, heat, stress):
  → the vegetative cell can turn into a spore (sporulation)

• When conditions improve:
  → the spore becomes a vegetative cell again (germination)

• It is the same organism, just in a different form

---

⚖ Vegetative Cell vs Spore

Vegetative Cell

• Active and growing

• Reproducing

• Low resistance (easily killed)

Spore

• Dormant (inactive)

• Not reproducing

• Highly resistant (survives harsh conditions)

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🩺 Why It Matters

• Vegetative cells are what cause active infections

• They are the target of antibiotics and disinfectants

• Much easier to kill than spores

Sterilization

✨ Definition

Complete destruction of ALL microorganisms, including bacteria, viruses, fungi, and spores

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🔑 Key Concept

• Must eliminate all forms of life

• Includes spores (this is what makes it sterilization)

• If any microbes survive → not sterilized

---

🔥 Methods of Sterilization

Heat (most common)

• Autoclave (steam under pressure) ⭐

• Dry heat / incineration

Filtration

• Removes microorganisms from liquids (heat-sensitive items)

Radiation

• UV (surface sterilization)

• Ionizing radiation (deep penetration)

Chemicals

• Gas (ethylene oxide)

• Strong liquid sterilants

---

⚖ Sterilization vs Disinfection

Sterilization

• Kills all microorganisms

• Kills spores

Disinfection

• Kills most microorganisms

• Does NOT reliably kill spores

---

🩺 Why It Matters

• Required for surgical instruments and medical equipment

• Prevents transmission of infection

• Important because spores are highly resistant

Disinfection

✨ Definition

Elimination of most microorganisms on nonliving surfaces, but NOT spores

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🔑 Key Concept

• Kills most pathogens (bacteria, viruses, fungi)

• Does NOT reliably kill spores

• Used on inanimate objects (not living tissue)

• Less effective than sterilization

---

🔥 Methods of Disinfection

Chemical disinfectants (most common)

• Bleach

• Alcohol

• Hydrogen peroxide

Physical methods

• Boiling (does NOT kill spores)

• UV light (surface only)

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⚖ Disinfection vs Sterilization

Disinfection

• Kills most microbes

• Does NOT kill spores ❌

• Used on surfaces

Sterilization

• Kills all microbes

• Kills spores ✅

• Used for medical instruments

---

🩺 Why It Matters

• Reduces spread of infection on surfaces

• Common in hospitals and homes

• Important for infection control, but not enough for sterile procedures

Pasteurization

✨ Definition

Mild heat treatment used to reduce harmful microorganisms in liquids without destroying all microbes

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🔑 Key Concept

• Reduces pathogens, does NOT sterilize

• Does NOT kill spores ❌

• Preserves taste and quality of liquids

• Commonly used for milk, juice, and food products

---

🔥 How It Works (Heat + Time)

• HTST (High Temp, Short Time)
  → 72°C (161°F) for 15 seconds

• UHT (Ultra-High Temp)
  → 135°C (275°F) for a few seconds

👉 Higher temp = shorter time

---

🩺 Why It Matters

• Makes food safer to consume

• Prevents foodborne illness

• Extends shelf life without major changes in taste

Autoclave

✨ Definition

A device that uses steam under pressure to sterilize equipment by killing all microorganisms, including spores.

---

🔑 Key Concept

• Uses moist heat (steam) under high pressure

• Achieves sterilization (kills everything, including spores)

• Most reliable and commonly used method in healthcare

---

🔥 How It Works

• Standard setting:
  → 121°C (250°F) for 15–20 minutes under pressure

• Steam penetrates cells → denatures proteins → kills microbes

---

🧪 What It’s Used For

• Surgical instruments

• Glassware

• Culture media

• Medical and lab equipment

---

🩺 Why It Matters

• Ensures complete sterilization

• Prevents infection in medical settings

• Critical for patient safety

Antisepsis

✨ Definition

Use of chemicals on living tissue to reduce or eliminate microorganisms.

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🔑 Key Concept

• Used on living tissue (skin, wounds)

• Kills or inhibits most microorganisms

• Does NOT reliably kill spores

• Safer than disinfectants for the body

---

🔥 Common Antiseptics

• Alcohol (hand sanitizer)

• Iodine / iodophors

• Hydrogen peroxide

• Chlorhexidine

---

⚖ Antisepsis vs Disinfection

Antisepsis

• Used on living tissue

• Safe for skin

• Kills most microbes (not spores)

Disinfection

• Used on nonliving surfaces

• Stronger chemicals

• Not safe for tissue

---

🩺 Why It Matters

• Prevents infection in cuts, wounds, and procedures

• Used before injections or surgery

• Important for patient safety and hygiene

Vehicle

✨ Definition

A vehicle is a nonliving method of disease transmission, such as food, water, air, or blood.

---

🔑 Key Concept

• Type of indirect transmission

• Microbes are transferred through a contaminated source

• The vehicle itself is not alive

• Can infect multiple people

---

🔄 Common Vehicles

• Food (undercooked meat, contaminated produce)

• Water

• Blood

• Air (droplets, aerosols)

---

⚖ Vehicle vs Vector

Vehicle

• Nonliving ❌

• Example: water, food, surfaces

Vector

• Living organism ✅

• Example: mosquitoes, ticks

Fomite

✨ Definition

A nonliving object that is contaminated with microorganisms and can transmit infection.

---

🔑 Key Concept

• Type of indirect transmission

• Object becomes contaminated with pathogens

• Can transfer microbes when touched

• Not alive (unlike vectors)

---

🔄 Common Examples

• Doorknobs

• Phones

• Towels

• Utensils

• Medical equipment

---

⚖ Fomite vs Vector

Fomite

• Nonliving ❌

• Example: objects

Vector

• Living organism ✅

• Example: mosquitoes, ticks

Etiology

✨ Definition

The cause or origin of a disease

---

🔑 Key Concept

• Identifies what caused the disease

• Can be a pathogen (bacteria, virus, fungus, parasite)

• Can also be noninfectious (genetic, environmental, lifestyle)

---

🔄 Types of Etiology

Infectious

• Caused by microorganisms

• Example: bacteria, viruses

Noninfectious

• Not caused by pathogens

• Example: genetics, toxins, diet, environment

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⚖ Etiology vs Risk Factors

Etiology

• Direct cause of disease

Risk Factors

• Increase chance of disease

• Do NOT directly cause it

Syndrome

✨ Definition

A syndrome is a group of signs and symptoms that occur together and characterize a disease.

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🔑 Key Concept

• Not a single symptom → a collection

• Helps identify a disease pattern

• May not always identify the exact cause (etiology)

---

🔄 Signs vs Symptoms

Signs

• Objective, can be observed/measured

• Example: fever, rash

Symptoms

• Subjective, felt by patient

• Example: pain, fatigue

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⚖ Syndrome vs Disease

Syndrome

• Group of signs & symptoms

• Cause may be unknown

Disease

• Has a specific cause (etiology)

• Defined condition

Remission

✨ Definition

A period in which the signs and symptoms of a disease are reduced or disappear

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🔑 Key Concept

• Disease is still present, but less active or not causing symptoms

• Can be temporary or long-term

• Symptoms may return (relapse)

---

🔄 Types of Remission

Partial Remission

• Some symptoms improve

• Disease still detectable

Complete Remission

• No signs or symptoms present

• Disease may still exist at a microscopic level

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⚖ Remission vs Cure

Remission

• Symptoms decrease or disappear

• Disease can return ❗

Cure

• Disease is completely gone

• Does NOT return

Resident microbiota

✨ Definition

Microorganisms that normally live on or in the body and are usually harmless or beneficial

---

🔑 Key Concept

• Found on skin, mouth, gut, and other body sites

• Normally do not cause disease

• Can become opportunistic pathogens if conditions change

• Help maintain a healthy balance in the body

---

🔄 Functions

• Compete with harmful microbes (prevent infection)

• Help with digestion (especially in gut)

• Produce vitamins (like vitamin K)

• Support the immune system

---

⚖ Resident vs Transient Microbiota

Resident Microbiota

• Long-term, stable

• Hard to remove

Transient Microbiota

• Temporary

• Easily removed (handwashing)

Transient microbiota

✨ Definition

Microorganisms that are temporarily present on or in the body and do not permanently colonize

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🔑 Key Concept

• Present for a short time (hours to days)

• Acquired from environment, people, or surfaces

• Do not normally establish long-term residence

• Can include pathogens

• Easily removed by handwashing and hygiene

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🔄 Characteristics

• Found on skin, hands, and mucous membranes

• May cause disease if they enter the body

• Less stable than resident microbiota

---

⚖ Transient vs Resident Microbiota

Transient Microbiota

• Temporary

• Easily removed

• May be harmful ❗

Resident Microbiota

• Permanent

• Stable

• Usually beneficial or harmless

---

🩺 Why It Matters

• Major source of infection transmission

• Important in healthcare hygiene (handwashing!)

• Can introduce pathogens into the body

Antibody

✨ Definition

A protein produced by B cells that specifically binds to and helps eliminate antigens (foreign substances)

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🔑 Key Concept

• Part of the adaptive (specific) immune system

• Highly specific → each antibody matches one antigen

• Produced by B lymphocytes (plasma cells)

• Circulates in blood and body fluids

• Vaccine gives you the antigen → your body makes the antibody.

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🔄 Functions

• Neutralization → blocks toxins/viruses from entering cells

• Opsonization → tags pathogens for destruction

• Agglutination → clumps pathogens together

• Activates complement system → enhances immune response

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⚖ Antibody vs Antigen

Antibody

• Made by the body

• Binds to antigens

Antigen

• Foreign substance (bacteria, virus, toxin)

• Triggers immune response

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🧪 Major Types (know these!)

• IgG → most abundant, long-term immunity

• IgA → found in mucus, saliva, breast milk

• IgM → first antibody produced

• IgE → allergies, parasites

• IgD → role in B cell activation

Antigen

✨ Definition

A foreign substance that triggers an immune response, especially the production of antibodies

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🔑 Key Concept

• Recognized as “non-self” by the immune system

• Stimulates production of antibodies

• Can be found on pathogens, toxins, or foreign cells

• Often located on the surface of microbes

---

🔄 Common Types of Antigens

• Bacteria

• Viruses

• Fungi

• Parasites

• Toxins

• Foreign cells (like mismatched blood cells)

---

⚖ Antigen vs Antibody

Antigen

• Foreign substance

• Triggers immune response

Antibody

• Made by the body

• Binds to antigen

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🩺 Why It Matters

• Starts the immune response

• Important in infections and immunity

• Basis for vaccines and diagnostic tests

Chlorine Compounds

Mechanism of Action:

• Chlorine oxidizes (destroys) proteins and enzymes in microorganisms

• Disrupts cell metabolism → kills bacteria, viruses, and fungi

• In water → forms hypochlorous acid (HOCl), which is the active killer

---

Examples:

• Bleach (sodium hypochlorite) ← most common

• Chlorine tablets (used for water purification)

• Disinfecting sprays/wipes

---

Important Study Info (HIGH YIELD):

• Broad-spectrum → kills bacteria, viruses, fungi

• Works fast and cheap → widely used in hospitals + homes

• Used for:

  • Surface disinfection

  • Blood/body fluid spills (VERY important)

  • Water treatment

---

Limitations / Things to Know:

• Inactivated by organic matter (blood, feces, dirt ↓ effectiveness)

• Can be corrosive to metals

• Can irritate skin, eyes, lungs

• Strong odor

---

Exam Tips:

• Think: BLEACH = OXIDATION = PROTEIN DESTRUCTION

• If question mentions blood spill cleanup → answer is chlorine (bleach)

• If question says cheap, fast disinfectant → chlorine

• If it says doesn’t work well with organic material → chlorine

Glutaraldehyde

Mechanism of Action:

• Denatures proteins and enzymes

• Cross-links proteins → inactivates microbial structures and enzymes

• Disrupts cell function → leads to cell death

---

Examples:

• Cidex (most common clinical product)

---

Important Study Info (HIGH YIELD):

• High-level disinfectant / chemical sterilant

• Kills:

  • Bacteria

  • Viruses

  • Fungi

  • Mycobacteria (VERY important)

  • Spores (with long exposure)

• Used for heat-sensitive medical equipment:

  • Endoscopes

  • Surgical instruments

---

Limitations / Things to Know:

• Toxic → can irritate skin, eyes, and lungs

• Requires proper ventilation

• Needs long contact time to achieve sterilization

• Not for use on living tissue

---

Exam Tips:

• Think: “cold sterilization” = glutaraldehyde

• Used when heat (autoclave) cannot be used

• If question mentions endoscopes → answer is glutaraldehyde

• Stronger than regular disinfectants

• medical instruments only, especially heat-sensitive equipment, and never used on skin.

Ethylene oxide

Mechanism of Action:

• Alkylates proteins and DNA

• Disrupts enzyme function and genetic material → prevents cell reproduction and survival

---

Examples:

• Ethylene oxide gas sterilization systems (used in hospitals)

---

Important Study Info (HIGH YIELD):

• Gas sterilization (VERY important)

• Kills:

  • Bacteria

  • Viruses

  • Fungi

  • Spores

• Used for heat-sensitive AND moisture-sensitive equipment:

  • Plastic materials

  • Electronics

  • Catheters

  • Surgical instruments

---

Limitations / Things to Know:

• Toxic and potentially carcinogenic ⚠

• Requires special equipment + controlled environment

• Slow process (takes hours)

• Items must be aerated after sterilization to remove toxic residue

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Exam Tips:

• Think: GAS sterilization = ethylene oxide

• Used when heat AND moisture cannot be used

• If question mentions plastic/electronics → ethylene oxide

• If it says alkylation of DNA → ethylene oxide

• gas, plastic devices, catheters, or cannot be autoclaved → ethylene oxide.

Alcohols

Mechanism of Action:

• Denature proteins

• Disrupt cell membranes (lipids) → causes cell leakage and death

---

Examples:

• Ethanol (70%)

• Isopropyl alcohol (70%) ← rubbing alcohol

---

Important Study Info (HIGH YIELD):

• Fast-acting disinfectant

• Kills:

  • Bacteria

  • Some fungi

  • Enveloped viruses (VERY important)

• Common uses:

  • Skin antiseptic (before injections)

  • Cleaning small instruments

  • Hand sanitizers

---

Limitations / Things to Know:

• Does NOT kill spores ❌

• Not effective against non-enveloped viruses (some)

• Evaporates quickly → short contact time

• Can dry out skin, used for SKIN PREP

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Exam Tips:

• Think: “70% alcohol = best” (better than 100% because water helps protein denaturation)

• If question mentions skin prep before injection → alcohol

• If it says fast but not sporicidal → alcohol

• If it says damages membranes → alcohol

• Alcohol is for skin prep and does NOT kill spores (not sterilization).

Ultraviolet (UV) light

Mechanism of Action:

• Causes DNA damage (thymine dimers)

• Prevents DNA replication → cells cannot reproduce → cell death

---

Examples:

• UV lamps (hospitals, labs)

• Used in biosafety cabinets

• Disinfection of air, water, and surfaces

---

Important Study Info (HIGH YIELD):

• Physical method (radiation)

• Kills:

  • Bacteria

  • Some viruses

  • Some fungi

• Common uses:

  • Surface disinfection

  • Air purification systems

  • Water treatment

---

Limitations / Things to Know:

• Poor penetration ❌ (does NOT go through glass, plastic, or solids well)

• Only works on directly exposed surfaces

• Not effective against spores

• Can damage skin and eyes

---

Exam Tips:

• Think: UV = DNA DAMAGE (thymine dimers)

• If question mentions surface/air disinfection → UV

• If it says doesn’t penetrate well → UV

• If it says radiation but not sterilization → UV

• If it mentions air, rooms, or surfaces and limited penetration, choose UV.

Gamma Rays and Xray

Mechanism of Action:

• Ionizing radiation → breaks DNA strands

• Produces free radicals → damages proteins, enzymes, and DNA

• Prevents replication → cell death

---

Examples:

• Sterilization of medical supplies (syringes, implants, gloves)

• Used in industrial sterilization + some food treatment

---

Important Study Info (HIGH YIELD):

• Highly penetrating (VERY important)

• Kill:

  • Bacteria

  • Viruses

  • Fungi

  • Spores ✅

• Used for pre-packaged items (can sterilize through packaging)

---

Key Difference:

• Gamma rays = more powerful, deeper penetration

• X-rays = similar but less penetrating

---

Limitations / Things to Know:

• Requires special equipment + strict safety controls

• Expensive

• Not used directly on living tissue for sterilization

---

Exam Tips:

• Think: IONIZING RADIATION = DNA BREAKS

• If question says sterilizes packaged equipment → gamma/X-ray

• pre-packaged medical supplies or food → gamma/X-ray

• If comparing radiation:

  • UV = weakest (surface only)

  • X-ray = medium

  • Gamma = strongest

Bactericidal vs Bacteriostatic

Mechanism of Action:

• Bactericidal: Kills bacteria directly → cell death

• Bacteriostatic: Inhibits growth and reproduction → stops bacteria from multiplying (immune system must finish the job)

---

Examples:

• Bactericidal:

  • Penicillin

  • Bleach (chlorine)

• Bacteriostatic:

  • Tetracycline

  • Sulfonamides

---

Important Study Info (HIGH YIELD):

• Bactericidal = “cidal = kill” 💀

• Bacteriostatic = “static = stop” ✋

• Bacteriostatic drugs rely on the immune system to eliminate bacteria

• Bactericidal is preferred for serious infections or immunocompromised patients

---

Limitations / Things to Know:

• Bacteriostatic does NOT kill bacteria ❌

• If immune system is weak → bacteriostatic may not be enough

• Some drugs can be either, depending on dose/concentration

---

Exam Tips:

• If question says kills bacteria → bactericidal

• If it says stops growth → bacteriostatic

• If patient is immunocompromised → choose bactericidal

• Watch for wording like “inhibits protein synthesis” → often bacteriostatic

Fungicidal vs Fungistatic

Mechanism of Action:

• Fungicidal: Kills fungi directly → cell death

• Fungistatic: Inhibits fungal growth and reproduction → stops spread (immune system clears it)

---

Examples:

• Fungicidal:

  • Amphotericin B

  • Nystatin

• Fungistatic:

  • Azoles (e.g., fluconazole)

---

Important Study Info (HIGH YIELD):

• Fungicidal = “cidal = kill” 💀

• Fungistatic = “static = stop” ✋

• Fungistatic drugs rely on the immune system

• Fungicidal is used for severe or systemic fungal infections

---

Limitations / Things to Know:

• Fungistatic does NOT kill fungi ❌

• May not work well in immunocompromised patients

• Some antifungals can be cidal or static depending on dose

---

Exam Tips:

• If question says kills fungus → fungicidal

• If it says inhibits growth → fungistatic

• Serious infection or weak immune system → fungicidal

• Same rule as bacteria:

  • cidal = kill

  • static = stop

Resistant

Definition:

• Microorganism is NOT affected by the antimicrobial drug

• The drug does not kill or stop growth

---

Mechanism (Why it happens):

• Bacteria may:

  • Break down the drug (enzymes)

  • Change the drug target

  • Pump the drug out (efflux pumps)

  • Prevent drug entry

---

Zone of Inhibition (What you see):

• No clear zone ❌

• Bacteria grow right up to the antibiotic disk

---

Important Study Info (HIGH YIELD):

• Drug is ineffective → should NOT be used

• Common with antibiotic resistance (e.g., MRSA)

• Major issue in healthcare

---

Exam Tips:

• NO zone = resistant

• If bacteria grow everywhere → resistant

• Keywords: “no effect,” “growth present,” “ineffective drug”

Intermediate

Definition:

• Microorganism has partial sensitivity to the antimicrobial

• Drug may work at higher doses or in certain body sites

---

Mechanism (What’s happening):

• Antibiotic has some effect, but not strong enough for full inhibition

• Bacteria are not fully resistant, but not fully susceptible

---

Zone of Inhibition (What you see):

• Medium-sized zone ⚠

• Some bacterial growth is inhibited, but not completely

---

Important Study Info (HIGH YIELD):

• Drug may be used if:

  • Higher dose is safe

  • Drug concentrates in specific body areas

• Considered a borderline result

---

Exam Tips:

• MEDIUM zone = intermediate

• Not the best choice, but may still work

• Think: “in between” susceptible and resistant

---

Susceptible

Definition:

• Microorganism is affected by the antimicrobial drug

• The drug kills or inhibits growth effectively

---

Mechanism (What’s happening):

• Antibiotic successfully reaches and damages the microbe

• May:

  • Break down cell wall

  • Disrupt protein synthesis

  • Damage DNA or metabolism

---

Zone of Inhibition (What you see):

• Large clear zone around the disk ✅

• Bacteria do NOT grow near the antibiotic

---

Important Study Info (HIGH YIELD):

• Drug is effective → good treatment choice

• Indicates bacteria are sensitive to the antibiotic

• Measured in millimeters (mm)

---

Exam Tips:

• BIG zone = susceptible

• If bacteria are absent around disk → drug works

• Keywords: “effective,” “sensitive,” “clear zone”

Cell Wall Synthesis Inhibitors

Type:

• Bactericidal 💀 (kills bacteria)

---

Mechanism of Action:

• Block formation of the bacterial cell wall (peptidoglycan)

• Stops bacteria from building their cell wall, causing the bacteria to burst and die.

• Weak cell wall → cell bursts (lysis) → death

---

Drug Examples:

• Penicillins (e.g., amoxicillin)

• Cephalosporins

• Vancomycin

---

Important Study Info (HIGH YIELD):

• Only work on bacteria with cell walls

• Human cells are NOT affected (no cell wall → selective toxicity)

• Especially effective against actively growing bacteria

---

Limitations / Things to Know:

• Do NOT work on viruses ❌

• Polymyxin B? → NO (Polymyxin B is GRAM-NEGATIVE membrane, not cell wall)

• Less effective if bacteria are not actively dividing

• Resistance can occur (e.g., MRSA)

---

Exam Tips:

• Think: “No wall = bacteria explodes” → bactericidal

• If question says peptidoglycan → cell wall inhibitor

• If it mentions penicillin → bactericidal

• If patient is immunocompromised → good choice (kills directly)

Protein synthesis inhibitor

Type:

• Bacteriostatic ✋ (most are)

• ⚠ Some can be bactericidal at high doses

---

Mechanism of Action:

• Bind to ribosomes (30S or 50S subunit)

• Block protein production → bacteria cannot grow or reproduce

• Stops bacteria from making proteins, which they need to grow and survive. Usually slows them down instead of killing them

---

Drug Examples:

Works by blocking ribosomes so bacteria can’t build proteins.

• Tetracyclines (30S)

• Macrolides (e.g., erythromycin) (50S)

• Aminoglycosides (exception → bactericidal)

---

Important Study Info (HIGH YIELD):

• Humans have different ribosomes → selective toxicity

• Stops bacterial growth → immune system clears infection

• Targets translation (protein making)

---

Limitations / Things to Know:

• Usually bacteriostatic (NOT killing directly) ❌

• Requires a working immune system

• Resistance can occur

---

Exam Tips:

• Think: “no proteins = no growth” → bacteriostatic

• If question says ribosome / 30S / 50S → protein inhibitor

• Aminoglycosides = exception (bactericidal)

• Keywords: translation, ribosome, protein

Disruption of Cell Membranes

Type:

• Bactericidal 💀 (kills bacteria)

---

Mechanism of Action:

• Damages the cell membrane (lipid bilayer)

• Damages or pokes holes in the bacteria’s cell membrane, causing everything inside to leak out

• Causes leakage of cell contents → cell dies

---

Drug Examples:

• Polymyxins (e.g., polymyxin B)

• She stressed that Polymyxin B is narrow-spectrum for Gram-negative bacteria. Membrane damage means the cell leaks and dies.

• Daptomycin

---

Important Study Info (HIGH YIELD):

• Targets the cell membrane integrity

• Works especially well on Gram-negative bacteria (polymyxins)

• Rapidly kills bacteria

---

Limitations / Things to Know:

• Can be toxic to human cells (since we also have membranes) ⚠

• Often used when other antibiotics don’t work (resistance cases)

• Not first-line treatment

---

Exam Tips:

• Think: “membrane destroyed → contents leak → death”

• If question says leakage or permeability → membrane disruption

• If it says rapid killing → bactericidal

• Keywords: membrane, leakage, permeability

Nucleic Acid Inhibition

Type:

• Bactericidal 💀 (kills bacteria)

---

Mechanism of Action:

• Inhibit DNA replication or RNA synthesis

• Prevent bacteria from copying genetic material → cell cannot reproduce → death

• If DNA or RNA replication is blocked, the bacteria cannot divide and will die.

---

Drug Examples:

• Fluoroquinolones (e.g., ciprofloxacin) → inhibit DNA replication

• Rifampin → inhibits RNA synthesis

• Metronidazole

---

Important Study Info (HIGH YIELD):

• Targets DNA or RNA processes

• Stops cell division and reproduction

• Often used for serious infections

---

Limitations / Things to Know:

• Can affect human cells slightly → side effects possible ⚠

• Resistance can develop

---

Exam Tips:

• Think: “no DNA/RNA = no replication = death”

• If question says DNA replication or transcription → nucleic acid inhibitor

• Keywords: DNA, RNA, replication, transcription

• Usually bactericidal

Metabolic Pathway Block (Antimetabolites)

Type:

• Bacteriostatic ✋

---

Mechanism of Action:

• Block essential metabolic pathways (especially folic acid synthesis)

• Bacteria cannot make DNA building blocks → cannot grow or reproduce

---

Drug Examples:

• Sulfonamides (sulfa drugs)

• Trimethoprim

• Bactrim (TMP-SMX combination)

---

Important Study Info (HIGH YIELD):

• Humans do NOT make folic acid → we get it from diet → selective toxicity

• Bacteria must synthesize folic acid → good target

• Stops growth → immune system clears infection

---

Limitations / Things to Know:

• Bacteriostatic (does NOT kill directly) ❌

• Requires a working immune system

• Resistance can occur

---

Exam Tips:

• Think: “no folic acid = no DNA = no growth”

• If question says folic acid pathway → metabolic inhibitor

• Keywords: antimetabolite, sulfa, folate

• Usually bacteriostatic

• “Stops growth but does NOT kill.” These drugs block folic acid pathways.

If pathogen A is more resistant to an erythromycin disc on a Kirby-Bauer plate compared to pathogen B, then pathogen A will have a(n) _______ zone of inhibition compared to pathogen B.

👉 Smaller (or no) zone of inhibition

---

Why:

• More resistant = antibiotic doesn’t work well

• So bacteria grow closer to the disk → smaller clear zone

---

Quick exam rule:

• Big zone = susceptible

• Small/no zone = resistant

Explain broad vs narrow spectrum antibiotics. Give examples of each.

Broad vs. Narrow Spectrum Antibiotics

Definitions:

• Broad-Spectrum Antibiotics:

  • Work against many types of bacteria

  • Cover Gram-positive AND Gram-negative

• Narrow-Spectrum Antibiotics:

  • Work against specific types of bacteria

  • Usually target only Gram-positive OR Gram-negative

---

Examples:

• Broad-Spectrum:

  • Tetracycline

  • Amoxicillin

• Narrow-Spectrum:

  • Penicillin G (mainly Gram-positive)

  • Isoniazid (specific for tuberculosis)

---

Important Study Info (HIGH YIELD):

• Broad-spectrum:

  • Used when cause is unknown

  • Treats a wide range of infections

• Narrow-spectrum:

  • Used when specific pathogen is known

  • More targeted treatment

---

Limitations / Things to Know:

• Broad-spectrum can:

  • Kill normal microbiota ⚠

  • Lead to superinfections (e.g., yeast infections)

  • Increase antibiotic resistance

• Narrow-spectrum:

  • Better for preserving normal flora

  • Lower risk of resistance

---

Exam Tips:

• Broad = many bacteria (Gram + and -)

• Narrow = specific bacteria

• If question says unknown infection → broad-spectrum

• If it says identified pathogen → narrow-spectrum

• Think: broad = shotgun, narrow = sniper

• Narrow-spectrum antibiotics target a specific group of bacteria, which helps preserve normal microbiota. An example emphasized in class is Polymyxin B, which targets Gram-negative bacteria only.

• If the organism is unknown, broad-spectrum may be used first; if the organism is known, narrow-spectrum is preferred

What factors contribute to antibiotic resistance?

Factors Contributing to Antibiotic Resistance

Main Causes:

• Overuse of antibiotics

  • Using antibiotics when not needed (e.g., viral infections)

• Misuse of antibiotics

  • Not finishing the full prescription

  • Skipping doses

• Incorrect prescribing

  • Wrong drug, dose, or duration

---

Biological Factors (What bacteria do):

• Mutations → random changes make bacteria resistant

• Horizontal gene transfer:

  • Conjugation (plasmids)

  • Transformation

  • Transduction

---

Healthcare & Environmental Factors:

• Poor infection control (spreads resistant bacteria)

• Use in livestock/agriculture

• Lack of new antibiotic development

---

Important Study Info (HIGH YIELD):

• Resistance = natural selection

  • Sensitive bacteria die → resistant ones survive & multiply

---

Exam Tips:

• Think:

  • Overuse + misuse = resistance

  • Not finishing meds → resistance

• Keywords: mutation, gene transfer, natural selection

• Antibiotic resistance is promoted by overuse and misuse of antibiotics, such as taking antibiotics for viral infections, not completing prescribed courses, unnecessary prescribing, and the use of antibiotics in agriculture. Poor infection control and lack of patient education also contribute.

• Overuse = resistance.

How do bacteria become resistant to antibiotics?

How Bacteria Become Resistant to Antibiotics

Main Mechanisms (HOW resistance happens):

• Enzyme production

  • Bacteria make enzymes that destroy the drug

  • Example: β-lactamase breaks penicillin

• Change in drug target

  • Antibiotic can’t bind anymore

  • Example: altered ribosome or cell wall proteins

• Efflux pumps

  • Bacteria pump the antibiotic out before it works

• Reduced permeability

  • Antibiotic can’t enter the cell

• Bypass pathways

  • Bacteria use an alternate metabolic pathway to survive

---

How They Get These Abilities:

• Mutations (random changes in DNA)

• Horizontal gene transfer:

  • Conjugation (plasmids)

  • Transformation (pick up DNA)

  • Transduction (via viruses)

---

Important Study Info (HIGH YIELD):

• This is natural selection:

  • Antibiotic kills sensitive bacteria

  • Resistant bacteria survive and multiply

---

Exam Tips:

• Think:

  • Destroy drug → enzyme

  • Change target → no binding

  • Pump it out → efflux

  • Block entry → permeability

• Keywords: β-lactamase, mutation, plasmid, efflux pump

• Bacteria become resistant through genetic mutations or by acquiring resistance genes from other bacteria through horizontal gene transfer (such as plasmids). These changes allow bacteria to inactivate the drug, prevent drug entry, pump the drug out, or alter the drug’s target.

• If the question asks how resistance happens, the answer involves mutations or gene transfer, not the patient.

Respiratory Tract – Portal of Entry

Definition:

• Pathogens enter the body through the nose, mouth, or lungs

• Spread mainly by inhalation of droplets or airborne particles

---

How Entry Happens (Mechanism):

• Microbes are breathed in

• Travel through upper (nose, throat) or lower (lungs) respiratory tract

• Attach to mucous membranes → infection begins

---

Examples of Diseases:

• Influenza (flu)

• Tuberculosis (TB)

• COVID-19

• Common cold

---

Important Study Info (HIGH YIELD):

• Spread by:

  • Droplets (coughing, sneezing)

  • Airborne transmission

• Very easy transmission between people

---

Limitations / Body Defenses:

• Mucus + cilia trap and move microbes out

• Coughing/sneezing helps remove pathogens

• Some microbes bypass defenses and infect lungs

---

Exam Tips:

• Think: “breathing in → respiratory”

• Keywords: droplets, airborne, inhalation

• If question mentions cough, sneezing, lungs → respiratory portal

Gastrointestinal (GI) Tract – Portal of Entry

Definition:

• Pathogens enter through the mouth and infect the digestive system

• Usually through contaminated food, water, or hands

---

How Entry Happens (Mechanism):

• Microbes are ingested (eaten or swallowed)

• Survive stomach acid → reach intestines

• Attach to intestinal lining → cause infection

---

Examples of Diseases:

• Salmonella (food poisoning)

• E. coli

• Norovirus

• Cholera

• Polio

---

Important Study Info (HIGH YIELD):

• Often called fecal-oral transmission 💩➡👄

• Common sources:

  • Undercooked food

  • Contaminated water

  • Poor hygiene

---

Limitations / Body Defenses:

• Stomach acid kills many microbes

• Normal microbiota compete with pathogens

• Some pathogens are acid-resistant → still cause infection

---

Exam Tips:

• Think: “eat/drink → GI tract”

• Keywords: contaminated food, fecal-oral, ingestion

• poultry = Salmonella

• If question mentions diarrhea/vomiting → likely GI entry

Genitourinary (Urogenital) Tract – Portal of Entry

Definition:

• Pathogens enter through the urinary or reproductive systems

• Commonly spread through sexual contact or poor hygiene

---

How Entry Happens (Mechanism):

• Microbes enter via urethra or genital tract

• Attach to mucous membranes → multiply and cause infection

---

Examples of Diseases:

• Urinary Tract Infections (UTIs) – E. coli

• Gonorrhea

• Chlamydia

• Herpes simplex virus (HSV)

---

Important Study Info (HIGH YIELD):

• Often transmitted through sexual contact (STIs)

• Can also result from bacteria entering urethra (poor hygiene, catheter use)

---

Limitations / Body Defenses:

• Urine flow helps flush microbes out

• Mucus and normal microbiota provide protection

• Shorter urethra in females → higher UTI risk

---

Exam Tips:

• Think: “urine + reproductive system → genitourinary”

• Keywords: UTI, STI, urethra, sexual transmission

• If question mentions burning urination or discharge → this portal

Breaches in the Skin – Portal of Entry

Definition:

• Pathogens enter through breaks in the skin

• Skin is normally a barrier, but cuts allow microbes in

---

How Entry Happens (Mechanism):

• Through:

  • Cuts, scrapes, wounds

  • Burns

  • Insect/animal bites

  • Needles or injections

• Microbes bypass the skin → enter tissues/blood → infection develops

---

Examples of Diseases:

• Tetanus (Clostridium tetani)

• Staphylococcus skin infections

• Rabies (animal bite)

• HIV / Hepatitis B & C (needle exposure)

---

Important Study Info (HIGH YIELD):

• Also called parenteral route when entering directly into tissues/blood

• Even small injuries can allow infection

---

Limitations / Body Defenses:

• Intact skin = strong barrier

• Once broken → high infection risk

• Immune response activates after entry

---

Exam Tips:

• Think: “cut or puncture → skin entry”

• Keywords: wound, bite, needle, break in skin

• If question mentions trauma/injury → this portal

Transplacental – Portal of Entry

Definition:

• Pathogens pass from mother to fetus through the placenta

• Infection occurs before birth (congenital infection)

---

How Entry Happens (Mechanism):

• Microbes in the mother’s blood cross the placenta

• Enter fetal circulation → infect developing fetus

---

Examples of Diseases:

• Rubella

• HIV

• Syphilis

• Toxoplasmosis

---

Important Study Info (HIGH YIELD):

• Can cause:

  • Birth defects

  • Miscarriage

  • Developmental issues

• Often remembered with TORCH infections:

  • Toxoplasmosis

  • Others (syphilis, etc.)

  • Rubella

  • Cytomegalovirus

  • Herpes

---

Limitations / Things to Know:

• Not all pathogens can cross the placenta

• Risk depends on timing of infection during pregnancy

---

Exam Tips:

• Think: “mother → fetus → placenta”

• Keywords: congenital, TORCH, birth defects

• If question mentions pregnancy transmission → transplacental

• IgG crosses the placenta

Sign

Definition:

• An objective indication of disease

• Something that can be observed or measured by others (healthcare provider)

---

Examples:

• Fever (elevated temperature)

• Rash

• Swelling

• High blood pressure

• Redness or inflammation

---

Important Study Info (HIGH YIELD):

• Can be seen, measured, or tested

• Opposite of a symptom (which is what the patient feels)

---

Exam Tips:

• Think: “SIGN = SEE” 👀

• If healthcare provider can observe it → sign

• If patient feels it → symptom

Symptom

Definition:

• A subjective indication of disease

• Something the patient feels and reports (not directly measured)

---

Examples:

• Pain

• Nausea

• Fatigue

• Dizziness

• Shortness of breath (feeling)

---

Important Study Info (HIGH YIELD):

• Cannot be directly observed by others

• Based on the patient’s experience

• Opposite of a sign

---

Exam Tips:

• Think: “SYMPTOM = something you SAY” 🗣

• If patient reports it → symptom

• If provider can measure/see it → sign

Biological Vector

Definition:

• A living organism that transmits a pathogen, where the pathogen develops or multiplies inside the vector

---

Mechanism (What makes it “biological”):

• Pathogen enters the vector

• Grows, reproduces, or undergoes part of its life cycle inside the vector

• Then transmitted to a new host

---

Examples:

• Mosquito → malaria (Plasmodium)

• Tick → Lyme disease (Borrelia)

• Mosquito → West Nile virus

---

Important Study Info (HIGH YIELD):

• Pathogen changes inside the vector (KEY difference)

• Vector is part of the pathogen’s life cycle

---

Exam Tips:

• Think: “BIO = pathogen grows inside”

• If question says life cycle or replication in vector → biological vector

• Keywords: mosquito, tick, development, multiplication

• A living organism (usually an insect) that not only carries the pathogen but the pathogen reproduces or grows inside it before being transmitted to a human. This vector is part of the pathogen’s life cycle.

Mechanical Vector

Definition:

• A living organism that carries a pathogen, but the pathogen does NOT develop or multiply inside it

---

Mechanism (What makes it “mechanical”):

• Pathogen is picked up on the body (legs, mouthparts, surface)

• Transported to another host → transmitted passively

---

Examples:

• Housefly → carries bacteria from feces to food

• Cockroach → spreads pathogens on surfaces

---

Important Study Info (HIGH YIELD):

• No life cycle or reproduction inside the vector ❌

• Just physical transport

---

Limitations / Things to Know:

• Less complex than biological vectors

• Still important in contamination and disease spread

---

Exam Tips:

• Think: “MECHANICAL = moving germs, not growing them”

• If question says carried on surface → mechanical vector

• Keywords: passive transfer, no development, contamination

• A living organism (still usually an insect) that carries pathogens on its body, but the pathogen does not grow or reproduce inside it. It just physically transfers germs from one place to another.

Polio Virus

Transmission:

• Fecal-oral route 💩➡👄 (MOST important)

• Spread through:

  • Contaminated food or water

  • Poor hygiene/sanitation

• Can also spread via oral-oral (saliva)

---

Disease / Infection:

• Caused by poliovirus

• Infects the gastrointestinal tract first, then can spread to the nervous system

---

Symptoms:

• Many cases: asymptomatic (no symptoms)

• Mild:

  • Fever

  • Sore throat

  • Fatigue

• Severe:

  • Muscle weakness

  • Flaccid paralysis (VERY important)

  • Can affect breathing → death

---

Important Study Info (HIGH YIELD):

• Virus can invade motor neurons in spinal cord

• Leads to permanent paralysis

• Mostly affects children

---

Prevention:

• Vaccination (VERY important) 💉

• Good sanitation and hygiene

---

Exam Tips:

• Think: “fecal-oral → nervous system → paralysis”

• Keywords: flaccid paralysis, motor neurons, vaccine-preventable

• If question mentions paralysis after GI symptoms → polio

Bordetella pertussis

Transmission:

• Respiratory droplets (coughing, sneezing)

• Spread person-to-person (highly contagious)

---

Disease / Infection:

• Causes Pertussis (Whooping Cough)

• Infects the respiratory tract

---

Mechanism (What it does):

• Bacteria attach to cilia in the trachea

• Release toxins → damage cilia

• Mucus builds up → severe coughing fits

---

Symptoms:

• Early:

  • Runny nose

  • Mild cough

• Late (VERY important):

  • Violent coughing fits

  • “Whooping” sound when inhaling

  • Vomiting after coughing

---

Important Study Info (HIGH YIELD):

• Cilia damage = cannot clear mucus

• Most dangerous in infants

• Can lead to breathing problems

---

Prevention:

• DTaP / Tdap vaccine 💉

---

Exam Tips:

• Think: “whooping cough = Bordetella pertussis”

• Keywords: coughing fits, whoop sound, cilia damage

• If question mentions prolonged coughing → pertussis

Rabies virus

Transmission:

• Animal bite 🐶🦇

• Virus in saliva enters through broken skin

• Common animals: dogs, bats, raccoons, skunks

---

Disease / Infection:

• Infects the nervous system (CNS)

• Travels from bite site → peripheral nerves → brain

---

Mechanism (What it does):

• Replicates in muscle → enters neurons

• Moves along nerves to the brain → causes encephalitis (brain inflammation)

---

Symptoms:

• Early:

  • Fever

  • Headache

• Late (VERY important):

  • Hydrophobia (fear of water)

  • Agitation, confusion

  • Paralysis → coma → death

---

Important Study Info (HIGH YIELD):

• Once symptoms appear → almost always fatal ⚠

• Slow progression → allows time for treatment

---

Prevention / Treatment:

• Post-exposure prophylaxis (PEP) 💉

  • Vaccine + immune globulin

• Clean wound immediately

---

Exam Tips:

• Think: “animal bite → nervous system → hydrophobia → death”

• Keywords: saliva, CNS, encephalitis, fatal

• If question mentions fear of water → rabies

Plasmodium Species

Transmission:

• Biological vector: female Anopheles mosquito 🦟

• Transmitted through mosquito bite (blood)

---

Disease / Infection:

• Causes Malaria

• Infects liver cells → then red blood cells (RBCs)

---

Mechanism (What it does):

• Parasite enters bloodstream → travels to liver

• Multiplies → released into blood → infects RBCs

• RBCs burst → causes cyclical symptoms

---

Symptoms:

• Cyclical fever and chills (VERY important)

• Sweating

• Fatigue

• Anemia (due to RBC destruction)

• Severe cases → organ damage or death

---

Important Study Info (HIGH YIELD):

• Eukaryotic parasite (NOT bacteria or virus)

• Life cycle involves human + mosquito

• Repeated RBC destruction → anemia

---

Prevention:

• Mosquito control (nets, repellents)

• Antimalarial drugs

---

Exam Tips:

• Think: “mosquito → liver → RBCs → cyclical fever”

• Keywords: malaria, RBC destruction, anemia, parasite

• If question mentions fever cycles → Plasmodium

Salmonella

Transmission:

• Fecal-oral route 💩➡👄

• Through contaminated food or water

• Common sources:

  • Undercooked poultry, eggs

  • Unpasteurized dairy

  • Poor food handling

---

Disease / Infection:

• Causes Salmonellosis (food poisoning)

• Infects the gastrointestinal (GI) tract

---

Mechanism (What it does):

• Bacteria invade intestinal lining

• Trigger inflammation → disrupt absorption

• Leads to diarrhea and fluid loss

---

Symptoms:

• Diarrhea (sometimes bloody)

• Abdominal cramps

• Fever

• Nausea and vomiting

---

Important Study Info (HIGH YIELD):

• One of the most common causes of foodborne illness

• Usually self-limiting (resolves on its own)

• Can be severe in young, elderly, immunocompromised

---

Prevention:

• Cook food thoroughly 🍗

• Wash hands and avoid cross-contamination

• Proper food storage

---

Exam Tips:

• Think: “undercooked chicken/eggs → diarrhea → Salmonella”

• Keywords: fecal-oral, food poisoning, GI infection

• If question mentions food + diarrhea → likely Salmonella

Herpes Simplex Virus (HSV)

Transmission:

• Direct contact with infected secretions or lesions

• Spread through:

  • Oral contact (kissing)

  • Sexual contact

---

Disease / Infection:

• Causes Herpes infections

  • HSV-1: oral herpes (cold sores)

  • HSV-2: genital herpes

---

Mechanism (What it does):

• Infects skin and mucous membranes

• Travels to nerve cells (latency)

• Can reactivate later → recurring outbreaks

---

Symptoms:

• Painful blisters/sores (VERY important)

• Itching or burning

• Fever (sometimes)

• Recurrent outbreaks

---

Important Study Info (HIGH YIELD):

• Latency in nerve ganglia (key concept)

• Lifelong infection → virus stays in body

• Triggered by stress, illness, weakened immunity

---

Prevention / Treatment:

• Avoid direct contact with lesions

• Antiviral drugs (e.g., acyclovir)

---

Exam Tips:

• Think: “blisters + latency in nerves → HSV”

• Keywords: cold sores, genital lesions, reactivation

• If question mentions recurrent outbreaks → herpes

Norovirus

Transmission:

• Fecal-oral route 💩➡👄

• Spread through:

  • Contaminated food or water

  • Person-to-person contact

  • Contaminated surfaces (fomites)

---

Disease / Infection:

• Causes acute gastroenteritis

• Infects the gastrointestinal (GI) tract

---

Mechanism (What it does):

• Infects intestinal cells → disrupts absorption

• Leads to inflammation and fluid loss

---

Symptoms:

• Vomiting (VERY important)

• Watery diarrhea

• Nausea

• Stomach cramps

---

Important Study Info (HIGH YIELD):

• Highly contagious ⚠

• Common in cruise ships, schools, hospitals

• Rapid onset + short duration

---

Prevention:

• Hand hygiene (VERY important)

• Disinfect contaminated surfaces

• Proper food handling

---

Exam Tips:

• Think: “sudden vomiting + diarrhea outbreak → norovirus”

• Keywords: highly contagious, fecal-oral, outbreaks

• If question mentions cruise ship → norovirus

HIV (Human Immunodeficiency Virus)

Transmission:

• Blood and body fluids

• Spread through:

  • Sexual contact

  • Needle sharing

  • Blood transfusions (rare now)

  • Transplacental (mother → fetus)

---

Disease / Infection:

• Causes HIV infection → can progress to AIDS

• Targets the immune system

---

Mechanism (What it does):

• Infects CD4 (T helper) cells

• Destroys immune cells over time → weakened immunity

• Leads to opportunistic infections

---

Symptoms:

• Early:

  • Flu-like symptoms

• Later:

  • Weight loss

  • Fatigue

  • Frequent infections

• Advanced (AIDS):

  • Severe opportunistic infections

---

Important Study Info (HIGH YIELD):

• Retrovirus (uses reverse transcriptase)

• Long asymptomatic period

• Progression leads to AIDS

---

Prevention / Treatment:

• Safe sex practices

• Do not share needles

• Antiretroviral therapy (ART) (controls virus, not cure)

---

Exam Tips:

• Think: “CD4 cells ↓ → weak immune system → infections”

• Keywords: retrovirus, AIDS, opportunistic infections

• If question mentions immune collapse → HIV

Enterobius vermicularis (Pinworm)

Transmission:

• Fecal-oral route 💩➡👄

• Spread by:

  • Ingesting eggs from contaminated hands, surfaces, or bedding

  • Autoinfection (scratching → eggs under nails → re-ingestion)

---

Disease / Infection:

• Causes Pinworm infection (Enterobiasis)

• Infects the gastrointestinal tract (intestines)

---

Mechanism (What it does):

• Eggs are swallowed → hatch in intestines

• Adult worms live in colon

• Females migrate to anus at night to lay eggs (VERY important)

---

Symptoms:

• Anal itching (especially at night) ⭐

• Restlessness / trouble sleeping

• Irritation around anus

• Sometimes mild abdominal discomfort

---

Important Study Info (HIGH YIELD):

• Common in children

• Diagnosed with tape test (eggs around anus)

• Easily spread in households, schools

---

Prevention / Treatment:

• Good hygiene (handwashing, clean nails)

• Wash bedding/clothing

• Antiparasitic meds (e.g., mebendazole)

---

Exam Tips:

• Think: “nighttime anal itching → pinworm”

• Keywords: fecal-oral, eggs, tape test, children

• If question mentions itching at night → Enterobius

Endemic

Definition:

• A disease that is constantly present in a specific geographic area or population

---

Examples:

• Malaria in parts of Africa

• Common cold (low-level presence worldwide)

---

Important Study Info (HIGH YIELD):

• Predictable and stable occurrence

• Not a sudden outbreak

• May have consistent number of cases over time

---

Compare (VERY IMPORTANT):

• Endemic = constant presence

• Epidemic = sudden increase in cases

• Pandemic = worldwide spread

---

Exam Tips:

• Think: “ENdemic = ENduring in one area”

• Keywords: constant, baseline, geographic area

• If question says always present → endemic

Epidemic

Definition:

• A sudden increase in the number of disease cases in a specific area or population

---

Examples:

• Flu outbreak in a city

• Measles outbreak in a community

---

Important Study Info (HIGH YIELD):

• Occurs above the normal (endemic) level

• Usually localized (not global)

• Often happens quickly

---

Compare (VERY IMPORTANT):

• Endemic = constant presence

• Epidemic = sudden spike in cases

• Pandemic = worldwide spread

---

Exam Tips:

• Think: “EPI = spike” 📈

• Keywords: outbreak, sudden increase, localized

• If cases are higher than expected → epidemic

Pandemic

Definition:

• A disease that spreads across multiple countries or continents

• A worldwide epidemic

---

Examples:

• COVID-19

• Influenza pandemics

---

Important Study Info (HIGH YIELD):

• Large-scale, global spread 🌍

• Affects many people across different regions

• Usually starts as an epidemic → spreads worldwide

---

Compare (VERY IMPORTANT):

• Endemic = constant presence in one area

• Epidemic = sudden increase in one area

• Pandemic = global spread

---

Exam Tips:

• Think: “PAN = all” (worldwide) 🌎

• Keywords: global, worldwide, multiple countries

• If question says across continents → pandemic

1st Line of Defense

Description:

• The body’s first, non-specific barrier against pathogens

• Prevents microbes from entering the body

---

Examples:

Physical Barriers:

• Skin

• Mucous membranes

Mechanical Defenses:

• Cilia (move mucus out)

• Coughing & sneezing

Chemical Defenses:

• Stomach acid

• Lysozyme (in tears & saliva)

• Sebum (skin oils)

---

Important Study Info (HIGH YIELD):

• Non-specific (innate immunity)

• Always active → first protection

• If this fails → infection can begin

---

Exam Tips:

• Think: “keeps pathogens OUT” 🚫

• Keywords: barrier, skin, mucus, acid

• If question says prevents entry → 1st line

2nd Line of Defense

Description:

• The body’s second, non-specific response after pathogens enter

• Works to fight and destroy invading microbes inside the body

---

Examples:

Cells:

• Phagocytes (neutrophils, macrophages) → engulf pathogens

• Natural Killer (NK) cells → kill infected cells

Processes:

• Inflammation → redness, swelling, heat, pain

• Fever → slows pathogen growth

Proteins:

• Complement system → destroys microbes

• Interferons → block viral replication

---

Important Study Info (HIGH YIELD):

• Non-specific (innate immunity)

• Activated when 1st line is breached

• Acts quickly, but not targeted to a specific pathogen

---

Exam Tips:

• Think: “fights invaders inside the body” ⚔

• Keywords: inflammation, fever, phagocytosis

• If question mentions redness/swelling → 2nd line

• Internal nonspecific defenses that activate when something gets past the 1st line. Includes inflammation, fever, and phagocytes.

3rd Line of Defense

Description:

• The body’s specific (adaptive) immune response

• Targets specific pathogens using immune memory

---

Examples:

Cells:

• B cells → produce antibodies

• T cells:

  • Helper T cells (CD4) → activate immune response

  • Cytotoxic T cells (CD8) → kill infected cells

Molecules:

• Antibodies → bind and neutralize pathogens

---

Important Study Info (HIGH YIELD):

• Specific immunity (targets exact pathogen)

• Has memory → faster response next time

• Basis of vaccination 💉

---

Limitations / Things to Know:

• Slower to respond the first time

• Becomes faster with repeated exposure

---

Exam Tips:

• Think: “targeted attack + memory” 🎯

• Keywords: antibodies, B cells, T cells, adaptive immunity

• If question mentions memory or vaccines → 3rd line

Naturally acquired passive immunity

Type of Immunizing Agent:

• Antibodies (given, not made by your body)

---

Source of Antibodies:

• Another person (usually mother)

---

Examples:

• Maternal antibodies crossing placenta (IgG)

• Breast milk (IgA)

---

Important Study Info (HIGH YIELD):

• Immediate protection ⚡

• Temporary (no memory cells formed)

• No activation of the person’s own immune system

---

Exam Tips:

• Think:

  • Natural = from body (not medical)

  • Passive = given antibodies

• Keywords: mother, placenta, breast milk, temporary

• If question says baby gets immunity from mom → Naturally acquired passive immunity

• A fetus receives IgG antibodies from the mother through the placenta; antibodies in breast milk provide protection. The baby does not make the antibodies.

Naturally acquired active immunity

Type of Immunizing Agent:

• Antigen (pathogen exposure)

---

Source of Antibodies:

• Your own immune system produces antibodies

---

Examples:

• Getting infected with a disease and recovering

  • Example: chickenpox infection → immunity later

---

Important Study Info (HIGH YIELD):

• Long-lasting immunity (often lifelong)

• Produces memory cells

• Takes time to develop

---

Exam Tips:

• Think:

  • Natural = infection/exposure

  • Active = your body makes antibodies

• Keywords: infection, memory cells, long-term protection

• If question says you got sick and then immune → Naturally acquired active immunity

• Getting measles naturally exposes the body to the antigen, causing the immune system to make its own antibodies and memory cells.

Artificially acquired passive immunity

Type of Immunizing Agent:

• Antibodies (given through medical treatment)

---

Source of Antibodies:

• Another human or animal (lab-produced or donor antibodies)

---

Examples:

• Rabies immune globulin (RIG)

• Antivenom (snake bites)

• Monoclonal antibody treatments

---

Important Study Info (HIGH YIELD):

• Immediate protection ⚡

• Temporary (no memory cells formed)

• Used for emergencies or exposure after infection risk

---

Exam Tips:

• Think:

  • Artificial = medical treatment

  • Passive = given antibodies

• Keywords: injection of antibodies, immune globulin, antivenom

• If question says given antibodies after exposure → Artificially acquired passive immunity

• Rabies immune globulin or a COVID antibody injection provides immediate, pre-made antibodies. The body does not produce antibodies or memory cells.

Artificially acquired active immunity

Type of Immunizing Agent:

• Antigen (vaccine)

---

Source of Antibodies:

• Your own immune system produces antibodies

---

Examples:

• Vaccinations 💉

  • COVID-19 vaccine

  • Tdap

  • MMR

---

Important Study Info (HIGH YIELD):

• Long-lasting protection

• Produces memory cells

• Takes time to develop immunity

---

Exam Tips:

• Think:

  • Artificial = medical (vaccine)

  • Active = your body makes antibodies

• Keywords: vaccine, antigen, memory cells

• If question says shot that trains immune system → Artificially acquired active immunity

• DTaP vaccine introduces antigens, causing the immune system to make antibodies and memory cells.

IgM (Immunoglobulin M)

Description:

• First antibody produced during an infection

• Indicates a recent or current infection

• Large, pentamer-shaped antibody → very effective at agglutination

---

Example:

• Positive IgM test for a disease (e.g., COVID, hepatitis) → means current/recent infection

---

Important Study Info (HIGH YIELD):

• Appears early in immune response

• Activates the complement system

• Does not last long

---

Exam Tips:

• Think: “IgM = Immediate” ⏱

• Keywords: first, early, recent infection

• If question asks which antibody appears first → IgM

IgA (Immunoglobulin A)

Description:

• Antibody found in mucosal areas and secretions

• Protects body surfaces exposed to the environment

---

Examples:

• Found in:

  • Saliva

  • Tears

  • Breast milk

  • Mucus (respiratory & GI tract)

---

Important Study Info (HIGH YIELD):

• Provides local immunity (not mainly in blood)

• Helps prevent pathogen attachment to mucosal surfaces

• Important for infant protection via breast milk

---

Exam Tips:

• Think: “IgA = A for Airway & secretions” 💧

• Keywords: mucosa, secretions, breast milk

• If question mentions saliva/tears/mucus → IgA

IgD (Immunoglobulin D)

Description:

• Found mainly on the surface of B cells

• Functions as a receptor that helps activate B cells

---

Example:

• Present on naive B cells (before they are activated)

---

Important Study Info (HIGH YIELD):

• Plays a role in starting the immune response

• Not commonly found in high levels in blood

• Less understood compared to other antibodies

---

Exam Tips:

• Think: “IgD = B cell Detector” 🔍

• Keywords: B cell receptor, activation

• If question mentions B cell surface → IgD

IgE (Immunoglobulin E)

Description:

• Antibody involved in allergic reactions and parasitic infections

• Binds to mast cells and basophils

---

Example:

• Allergies (e.g., pollen, peanuts)

• Asthma

• Defense against parasites (helminths)

---

Important Study Info (HIGH YIELD):

• Triggers histamine release → causes allergy symptoms

• Leads to:

  • Itching

  • Swelling

  • Bronchoconstriction

---

Exam Tips:

• Think: “IgE = Allergy & Eosinophils” 🤧

• Keywords: histamine, mast cells, allergies, parasites

• If question mentions allergic reaction → IgE

IgG (Immunoglobulin G)

Description:

• Most abundant antibody in blood

• Provides long-term protection after infection or vaccination

---

Example:

• Positive IgG test → indicates past infection or immunity

• Maternal IgG crosses the placenta → protects fetus

---

Important Study Info (HIGH YIELD):

• Main antibody of secondary (memory) response

• Provides long-lasting immunity

• Can cross the placenta (VERY important)

---

Exam Tips:

• Think: “IgG = Gone (past infection)”

• Keywords: long-term, memory, most abundant, placenta

• If question asks which antibody gives lasting immunity → IgG

Meningitis

Disease Characteristics:

• Inflammation of the meninges (protective membranes around brain & spinal cord)

• Can be bacterial, viral, or fungal

• Bacterial meningitis = most severe ⚠

---

Causative Agents:

• Bacterial:

  • Neisseria meningitidis ⭐

  • Streptococcus pneumoniae

  • Haemophilus influenzae

• Viral (more common, less severe):

  • Enteroviruses

  • Herpes simplex virus

• Fungal (rare):

  • Cryptococcus

---

Signs & Symptoms:

Classic triad (VERY important):

• Fever

• Neck stiffness (nuchal rigidity)

• Altered mental status

Other symptoms:

• Severe headache

• Photophobia (light sensitivity)

• Nausea/vomiting

• Seizures (severe cases)

---

Important Study Info (HIGH YIELD):

• Medical emergency 🚨 (especially bacterial)

• Spread via respiratory droplets (common types)

• Can lead to brain damage or death if untreated

---

Exam Tips:

• Think: “fever + stiff neck + confusion → meningitis”

• Keywords: meninges, nuchal rigidity, photophobia

• If question mentions neck stiffness → meningitis

Encephalitis

Disease Characteristics:

• Inflammation of the brain tissue ⚠

• Usually caused by a viral infection

• Can affect brain function and consciousness

---

Causative Agents:

• Viruses (most common):

  • Herpes simplex virus (HSV) (VERY important)

  • West Nile virus

---

Signs & Symptoms:

• Fever

• Headache

• Confusion / altered mental status

• Seizures

• Behavior changes

• Coma (severe cases)

---

Important Study Info (HIGH YIELD):

• Brain inflammation (not meninges)

• Often follows a viral infection

• Can cause permanent brain damage

---

Exam Tips:

• Think: “brain inflammation → confusion + seizures”

• Keywords: HSV, altered mental status, seizures

• If question mentions brain dysfunction → encephalitis

---

Quick Compare (SUPER IMPORTANT):

• Meningitis = meninges (neck stiffness)

• Encephalitis = brain (confusion, seizures)

Conjunctivitis

Disease Characteristics:

• Inflammation of the conjunctiva (thin membrane covering the eye)

• Can be bacterial, viral, or allergic

• Highly contagious (infectious types)

---

Causative Agents:

• Bacterial: ⭐

  • Staphylococcus aureus

  • Streptococcus pneumoniae

• Viral (most common):

  • Adenovirus

• Allergic (non-infectious):

  • Pollen, dust, allergens

---

Signs & Symptoms:

• Red/pink eye (VERY important)

• Discharge:

  • Thick/yellow (bacterial)

  • Watery (viral)

• Itching (especially allergic)

• Tearing

• Crusting of eyelids

---

Important Study Info (HIGH YIELD):

• Spread by direct contact or contaminated objects (fomites)

• Often starts in one eye → spreads to the other

• Usually self-limiting (viral)

---

Exam Tips:

• Think: “red eye + discharge → conjunctivitis”

• Keywords: pink eye, adenovirus, discharge type

• If question mentions sticky/crusty eyes → bacterial conjunctivitis

Keratitis

Disease Characteristics:

• Inflammation of the cornea (clear front part of the eye)

• Can be infectious or non-infectious

• Can lead to vision loss if untreated ⚠

---

Causative Agents:

• Bacterial:

  • Pseudomonas aeruginosa (VERY important, esp. contact lenses)

• Viral:

  • Herpes simplex virus (HSV) ⭐

• Fungal:

  • Fusarium, Aspergillus

• Protozoan:

  • Acanthamoeba (contact lens users)

---

Signs & Symptoms:

• Eye pain ⭐

• Redness

• Blurred vision

• Light sensitivity (photophobia)

• Excess tearing

• Feeling like something is in the eye

---

Important Study Info (HIGH YIELD):

• Strongly associated with contact lens use ⚠

• Can cause corneal ulcers

• More serious than conjunctivitis

---

Exam Tips:

• Think: “cornea + pain + vision changes → keratitis”

• Keywords: contact lenses, photophobia, corneal damage

• If question mentions eye pain (not just redness) → keratitis

---

Quick Compare:

• Conjunctivitis = conjunctiva (redness, discharge)

• Keratitis = cornea (pain + vision problems)

Endocarditis

Disease Characteristics:

• Infection of the endocardium (inner lining of the heart, especially valves)

• Usually serious and potentially life-threatening ⚠

---

Causative Agents:

• Bacteria (MOST common):

  • Staphylococcus aureus

  • Streptococcus viridans (often from dental sources)

  • Enterococcus species

• Fungi (less common):

  • Candida species

---

Signs & Symptoms:

• Fever ⭐

• Heart murmur

• Fatigue

• Chills

• Shortness of breath

Classic findings (HIGH YIELD):

• Petechiae

• Janeway lesions (painless)

• Osler nodes (painful)

---

Important Study Info (HIGH YIELD):

• Bacteria enter bloodstream → attach to damaged heart valves

• Risk factors:

  • Dental procedures 🦷

  • IV drug use

• Can cause embolism or heart damage

---

Exam Tips:

• Think: “bacteria + heart valves → murmur + fever”

• Keywords: Staph, Strep, valves, bloodstream infection

• If question mentions murmur + infection → endocarditis

Catheter Related Bloodstream Infections (CRBIs)

Disease Characteristics:

• Infection occurs when microorganisms enter the bloodstream via a catheter

• Common healthcare-associated infection (HAI) ⚠

---

Causative Agents:

• Bacteria:

  • Staphylococcus epidermidis (most common, skin flora)

  • Staphylococcus aureus

  • Enterococcus species

• Fungi:

  • Candida species

---

How It Happens (Mechanism):

• Microbes from skin or environment contaminate catheter

• Form biofilm on catheter surface

• Enter bloodstream → systemic infection (sepsis risk)

---

Signs & Symptoms:

• Fever ⭐

• Chills

• Redness/swelling at insertion site

• Possible sepsis (low BP, confusion in severe cases)

---

Important Study Info (HIGH YIELD):

• Bacteria = most common cause

• Biofilm formation = KEY concept

• Often linked to IV lines / central lines

---

Exam Tips:

• Think: “catheter → bacteria/fungi → biofilm → bloodstream infection”

• Keywords: Staph epidermidis (bacteria), Candida (fungi)

Cellulitis

Disease Characteristics:

• Bacterial infection of the skin and subcutaneous tissue

• Spreads through breaks in the skin (cuts, wounds, insect bites)

---

Causative Agents:

• Bacteria (MOST common):

  • Streptococcus pyogenes

  • Staphylococcus aureus (including MRSA)

---

Signs & Symptoms:

• Redness (erythema) ⭐

• Swelling

• Warmth

• Pain/tenderness

• Fever (in more severe cases)

---

Important Study Info (HIGH YIELD):

• Infection spreads rapidly through skin layers

• Borders are often poorly defined

• Can become serious if it spreads to bloodstream

---

Risk Factors:

• Breaks in skin

• Poor circulation

• Diabetes

• Weakened immune system

---

Exam Tips:

• Think: “red, warm, swollen skin → cellulitis”

• Keywords: Strep, Staph, skin infection, spreading redness

• If question mentions diffuse skin infection → cellulitis

Erysipelas

Disease Characteristics:

• Superficial bacterial skin infection (upper dermis)

• Often affects the face or legs

• More well-defined than cellulitis

---

Causative Agents:

• Bacteria (MOST common):

  • Streptococcus pyogenes (Group A Strep) ⭐

---

Signs & Symptoms:

• Bright red, raised rash ⭐

• Well-defined borders (VERY important)

• Swelling

• Warmth

• Pain

• Fever and chills

---

Important Study Info (HIGH YIELD):

• Infection is more superficial than cellulitis

• Has sharp, distinct borders

• Rapid onset

---

Exam Tips:

• Think: “raised, bright red, sharp borders → erysipelas”

• Keywords: Strep pyogenes, superficial, well-defined edges

---

Quick Compare:

• Erysipelas = superficial + sharp borders

• Cellulitis = deeper + blurry borders

Necrotizing Fasciitis

Disease Characteristics:

• Severe, rapidly spreading infection of fascia (deep tissue) ⚠

• Causes tissue death (necrosis)

• Known as “flesh-eating disease”

---

Causative Agents:

• Bacteria (MOST common):

  • Streptococcus pyogenes (Group A Strep) ⭐

  • Staphylococcus aureus

  • Mixed bacteria (polymicrobial infections)

---

Signs & Symptoms:

• Severe pain (out of proportion to wound) ⭐

• Swelling

• Redness → progresses to purple/black tissue

• Fever

• Blisters (bullae)

• Tissue necrosis

---

Important Study Info (HIGH YIELD):

• Spreads very quickly along fascia

• Medical emergency 🚨

• Can lead to sepsis, shock, death

---

Risk Factors:

• Cuts, wounds, surgery

• Diabetes

• Immunocompromised patients

---

Exam Tips:

• Think: “extreme pain + rapid tissue death → necrotizing fasciitis”

• Keywords: flesh-eating, fascia, necrosis, rapid spread

• If question says pain out of proportion → this

---

Quick Compare:

• Cellulitis = mild/moderate skin infection

• Erysipelas = superficial, well-defined

• Necrotizing fasciitis = deep, severe, deadly

Appendicitis

Disease Characteristics:

• Inflammation of the appendix ⚠

• Usually due to obstruction → infection develops

• Can lead to rupture (medical emergency)

---

Causative Agents:

• Bacteria (MOST common, from normal GI flora):

  • Escherichia coli (E. coli)

  • Bacteroides species (anaerobic bacteria)

---

Signs & Symptoms:

• Abdominal pain (starts near navel → moves to right lower quadrant) ⭐

• Loss of appetite

• Nausea/vomiting

• Fever

• Rebound tenderness

---

Important Study Info (HIGH YIELD):

• Caused by blockage (fecalith, lymph tissue) → bacteria multiply

• Risk of rupture → peritonitis (VERY serious)

• Requires surgical removal (appendectomy)

---

Exam Tips:

• Think: “RLQ pain + nausea + fever → appendicitis”

• Keywords: E. coli, obstruction, rupture risk

• If question mentions pain shifting to lower right abdomen → Appendicitis

Acute cholecystitis

Disease Characteristics:

• Inflammation of the gallbladder ⚠

• Usually caused by gallstone blockage of the cystic duct

• Can lead to infection and bile buildup

---

Causative Agents:

• Bacteria (secondary infection):

  • Escherichia coli (E. coli)

  • Klebsiella species

  • Enterococcus species

---

Signs & Symptoms:

• Right upper quadrant (RUQ) abdominal pain ⭐

• Pain may radiate to right shoulder

• Fever

• Nausea/vomiting

• Murphy’s sign (pain when pressing RUQ during inspiration)

---

Important Study Info (HIGH YIELD):

• Often starts with gallstones (not infection first)

• Bacteria may infect trapped bile → worsens condition

• Can lead to rupture or sepsis if untreated

---

Exam Tips:

• Think: “RUQ pain + gallstones → cholecystitis”

• Keywords: E. coli, bile, Murphy’s sign, gallbladder

• If question mentions pain after fatty meals → Acute cholecystitis

Herpes Simplex Virus (HSV-1 & HSV-2)

Disease Characteristics:

• Viral infection of skin and mucous membranes

• Causes painful blisters/lesions

• Establishes latent infection in nerve cells → lifelong

---

Causative Agents:

• Virus:

  • HSV-1 → oral herpes (cold sores)

  • HSV-2 → genital herpes

---

Transmission:

• Direct contact with lesions or body fluids

• HSV-1: kissing, oral contact

• HSV-2: sexual contact

---

Signs & Symptoms:

• Painful fluid-filled blisters ⭐

• Burning/tingling before outbreak

• Fever (initial infection)

• Recurrent outbreaks

---

Important Study Info (HIGH YIELD):

• Virus remains latent in nerve ganglia

• Can reactivate (stress, illness, immunosuppression)

• No cure → managed with antivirals

---

Exam Tips:

• Think: “painful blisters + latency → HSV”

• Keywords: HSV-1 oral, HSV-2 genital, recurrence

• If question mentions recurrent lesions → herpes

---

Quick Compare:

• HSV-1 = oral (mouth)

• HSV-2 = genital

Human Immunodeficiency Virus (HIV)

Disease Characteristics:

• Viral infection that attacks the immune system

• Can progress to AIDS (Acquired Immunodeficiency Syndrome) ⚠

• Leads to severe immune suppression

---

Causative Agent:

• Virus:

  • HIV (a retrovirus)

---

Transmission:

• Blood and body fluids

• Spread through:

  • Sexual contact

  • Needle sharing (IV drug use)

  • Blood transfusion (rare)

  • Transplacental (mother → baby)

---

Mechanism (What it does):

• Infects CD4 (T helper) cells

• Uses reverse transcriptase to replicate

• Gradually destroys immune system

---

Signs & Symptoms:

• Early:

  • Flu-like symptoms

• Chronic:

  • Fatigue

  • Weight loss

  • Swollen lymph nodes

• Advanced (AIDS):

  • Opportunistic infections ⭐

---

Important Study Info (HIGH YIELD):

• Long asymptomatic phase

• Decreased CD4 count = disease progression

• No cure, but controlled with antiretroviral therapy (ART)

---

Exam Tips:

• Think: “CD4 cells ↓ → immune system weak → infections”

• Keywords: retrovirus, AIDS, opportunistic infections

• If question mentions immune collapse → HIV

Osteomyelitis

Disease Characteristics:

• Infection of the bone ⚠

• Can be acute or chronic

• Often spreads from bloodstream or nearby infection

---

Causative Agents:

• Bacteria (MOST common): ⭐

  • Staphylococcus aureus (most common overall)

  • Streptococcus species

• Other (less common):

  • Gram-negative bacteria (e.g., E. coli)

  • Fungi (rare cases)

---

Transmission / How It Occurs:

• Hematogenous spread (through bloodstream)

• Direct entry (injury, surgery, open fracture)

• Spread from nearby tissue infection

---

Signs & Symptoms:

• Bone pain ⭐

• Fever

• Swelling and redness over affected area

• Limited movement

---

Important Study Info (HIGH YIELD):

• Common in:

  • Children (long bones)

  • Adults (vertebrae, feet in diabetics)

• Can lead to bone destruction

• May require long-term antibiotics or surgery

---

Exam Tips:

• Think: “bone pain + infection → osteomyelitis”

• Keywords: Staph aureus, bone infection, hematogenous spread

• If question mentions infection after fracture/surgery → Osteomyelitis

Septic Arthritis

Disease Characteristics:

• Infection of a joint (synovial fluid and tissues) ⚠

• Causes rapid joint destruction if untreated

---

Causative Agents:

• Bacteria (MOST common): ⭐

  • Staphylococcus aureus (most common overall)

  • Neisseria gonorrhoeae (common in sexually active adults)

  • Streptococcus species

• Other (less common):

  • Fungi

  • Viruses (rare)

---

Transmission / How It Occurs:

• Hematogenous spread (through bloodstream)

• Direct entry from:

  • Injury

  • Surgery

  • Joint injection

---

Signs & Symptoms:

• Severe joint pain ⭐

• Swelling

• Redness and warmth

• Limited range of motion

• Fever

---

Important Study Info (HIGH YIELD):

• Usually affects one joint (monoarticular)

• Common joints:

  • Knee

  • Hip

• Medical emergency → can destroy joint quickly

---

Exam Tips:

• Think: “hot, swollen, painful joint → septic arthritis”

• Keywords: Staph aureus, joint infection, rapid damage

• If question mentions cannot move joint due to pain → this

---

Quick Compare:

• Osteomyelitis = bone infection

• Septic arthritis = joint infection

What are the risk factors for endocarditis?

Main Risk Factors:

• Damaged or abnormal heart valves ⭐

  • Congenital heart defects

  • Previous heart disease

• IV drug use 💉

  • Injecting drugs introduces bacteria directly into bloodstream

• Recent dental procedures 🦷

  • Oral bacteria can enter blood → infect heart valves

• Prosthetic (artificial) heart valves

  • Higher risk of bacterial attachment

• Previous history of endocarditis

  • Increased chance of recurrence

• Indwelling devices:

  • Catheters / IV lines

  • Pacemakers

• Weakened immune system

  • Diabetes

  • Immunocompromised patients

---

Important Study Info (HIGH YIELD):

• Key idea: anything that allows bacteria into bloodstream + damaged valves → endocarditis

---

Exam Tips:

• Think: “bacteria in blood + bad valve = endocarditis”

• Keywords: IV drug use, dental work, prosthetic valves

• If question mentions murmur + these risk factors → endocarditis

Conjunctivitis caused by which pathogen can progress rapidly and caused blindness if left untreated?

Answer:
👉 Neisseria gonorrhoeae

---

Why (HIGH YIELD):

• Causes gonococcal conjunctivitis

• Very aggressive infection

• Can rapidly damage the cornea → blindness if untreated ⚠

---

Exam Tip:

• If question says “rapid progression + risk of blindness + eye infection” → Neisseria gonorrhoeae

What is the diagnosis for meningitis and encephalitis?

Meningitis (Diagnosis):

• Lumbar puncture (spinal tap) ⭐

  • Analyze cerebrospinal fluid (CSF)

• Findings may include:

  • ↑ White blood cells

  • ↑ Protein

  • ↓ Glucose (especially bacterial)

• Additional tests:

  • Blood cultures

  • CT scan (before LP if needed)

---

Encephalitis (Diagnosis):

• Lumbar puncture (spinal tap) ⭐

  • Analyze cerebrospinal fluid (CSF)

• PCR testing (VERY important for viral causes like HSV)

• Brain imaging (MRI/CT)

• EEG (shows abnormal brain activity)

---

Important Study Info (HIGH YIELD):

• Both use CSF analysis (lumbar puncture)

• Meningitis = focus on meninges (CSF changes)

• Encephalitis = focus on brain (imaging + PCR important)

• The diagnosis for both meningitis and encephalitis is made using a lumbar puncture (spinal tap) to analyze cerebrospinal fluid

What pathogen is the most common cause of hospital associated colitis?

Answer:
👉 Clostridioides difficile

---

Why (HIGH YIELD):

• Most common cause of hospital-associated colitis

• Occurs after antibiotic use → normal microbiota destroyed

• Produces toxins → inflammation of colon (pseudomembranous colitis)

---

Exam Tips:

• Think: “hospital + antibiotics + diarrhea → C. diff”

• Keywords: antibiotic-associated diarrhea, toxin, colitis

Why are transmission rates high for many sexually transmitted infections?

Main Reasons:

• Direct mucous membrane contact ⭐

  • Genitals have thin, moist tissues → easy entry for pathogens

• Exchange of body fluids

  • Semen, vaginal fluids, blood → high pathogen load

• Often asymptomatic ⚠

  • People don’t know they are infected → continue spreading infection

• Multiple sexual partners

  • Increases exposure risk

• Lack of protection

  • Not using condoms → direct transmission

• High infectivity of pathogens

  • Some STI pathogens are very efficient at spreading

---

Important Study Info (HIGH YIELD):

• STIs spread easily because of intimate contact + fluid exchange

• Asymptomatic carriers are a major factor in spread

---

Exam Tips:

• Think: “mucous membranes + fluids + no symptoms = high spread”

• Keywords: asymptomatic, direct contact, body fluids

• Transmission rates are high because many STIs are asymptomatic, allowing infected individuals to spread the infection unknowingly, and because they are transmitted through direct mucous membrane contact (teacher tip: asymptomatic carriers were the main reason she emphasized).