Microbio Exam 3

Signs

Objective, observable indicators of disease (e.g., fever, rash)

Symptoms

Subjective feelings reported by patient (e.g., pain, fatigue)

Acute disease

Short duration, rapid onset

Chronic disease

Long-lasting disease

Latent disease

Inactive for a period, then reactivates

Transient flora

Temporary microbes on the body

Resident flora

Permanent microbes that normally live on the body

Sterile sites

Areas normally free of microbes (blood, CSF, organs)

Normal flora benefits

Protect against pathogens, help digestion, produce vitamins

Disruption of flora

Can cause infections or disease

Pathogen

Disease-causing microorganism

Virulence

Degree of pathogenicity

Opportunistic infection

Infection in weakened host

Endogenous infection

Infection from normal flora

ID50

Infectious dose for 50% of population

LD50

Lethal dose for 50% of population

Pathogenesis steps

Entry → attachment → invasion → damage

Exotoxins

Secreted toxins (proteins, highly potent)

Endotoxins

Released from Gram-negative bacteria cell walls

Local infection

Confined to one area

Systemic infection

Spreads throughout body

Primary infection

Initial infection

Secondary infection

Follows primary infection

Portal of exit

Route pathogen leaves host (respiratory, blood, etc.)

Endemic

Constant presence in a population

Epidemic

Sudden increase in cases

Pandemic

Worldwide spread

Reservoir

Natural habitat of pathogen

Carrier

Infected individual without symptoms

Definitive host

Where pathogen matures

Intermediate host

Temporary host

Direct contact

Person-to-person transmission

Indirect contact

Via objects (fomites)

Vehicle transmission

Food, water, air

Vector transmission

Insects/animals

Healthcare-associated infection (HAI)

Infection acquired in healthcare setting

Nosocomial infection

Another term for HAI

Innate immunity

Non-specific, immediate defense

Adaptive immunity

Specific, memory-based defense

1st line of defense

Skin, mucous membranes

2nd line of defense

Internal defenses (WBCs, inflammation)

3rd line of defense

Adaptive immune response

Physical defenses

Skin, mucus, cilia

Chemical defenses

Lysozyme, stomach acid

Cellular defenses

White blood cells

Granulocytes

Neutrophils, eosinophils, basophils

Agranulocytes

Lymphocytes, monocytes

Hematopoiesis

Formation of blood cells

Diapedesis

WBCs moving through blood vessel walls

Chemotaxis

Movement toward infection site

Inflammation

Redness, swelling, heat, pain

Fever

Increased body temperature to fight infection

Phagocytosis

Engulfing pathogens

Interferons

Antiviral proteins

Complement system

Enhances immune response

Antigen

Substance that triggers immune response

Antibody

Protein that binds antigen

Humoral immunity

B cells produce antibodies

Cell-mediated immunity

T cells attack infected cells

Immunoglobulins

IgG, IgA, IgM, IgE, IgD

MHC I

Found on all cells, presents to cytotoxic T cells

MHC II

Found on APCs, presents to helper T cells

APCs

Cells that present antigens (macrophages, dendritic cells)

Helper T cells

Activate other immune cells

Cytotoxic T cells

Kill infected cells

B cells

Produce antibodies

Clonal selection

Activation and multiplication of specific lymphocytes

Primary response

First exposure (slow, weak)

Secondary response

Second exposure (fast, strong)

Active immunity

Body produces its own antibodies

Passive immunity

Antibodies come from another source

Natural immunity

Through infection or maternal transfer

Artificial immunity

Through vaccines

Vaccine

Substance that stimulates immune memory

Herd immunity

Protection of population when many are immune

Staphylococcus aureus

Common cause of skin infections

Streptococcus

Causes strep infections, skin infections

Pseudomonas aeruginosa

Opportunistic infection (burns, wounds)

Bacillus anthracis

Causes anthrax

Conjunctivitis

Pinkeye infection

Neonatal conjunctivitis

Eye infection in newborns

Trachoma

Chronic eye infection leading to blindness

Keratitis

Corneal inflammation

HPV

Causes warts

Herpesviruses

Cause cold sores, shingles

Parvoviruses

Cause rash illnesses

Tinea

Fungal skin infections (ringworm)

Candidiasis

Yeast infection

Sporotrichosis

Fungal infection from soil/plants

Acanthamoeba

Eye infection (often from contact lenses)

Loiasis

Parasitic worm infection