Microbiology Test 1

Disease

A process causing damage to tissues or altered physiological function, identified by a set of signs and symptoms (syndrome). [1, 258]

Syndrome

The specific collection of signs and symptoms that together characterize a particular physiological disturbance or disease. [1, 258]

Pathogenesis

The biological mechanism explaining how and why physiology is changed in a disease. [1, 258]

Spontaneous Generation

The historical theory that living organisms could arise from non-living matter; disproved by Spallanzani, Pasteur, and Tyndall. [3, 259]

Louis Pasteur (Beer & Wine Experiment)

Disproved spontaneous generation by demonstrating that microorganisms are responsible for alcohol production in beer/wine and acetic acid in vinegar, proving they are active biological forces rather than mere chemical byproducts. [3, 259, 260]

The Germ Theory of Disease

Proposed by Henle (1840); states that contagions are living, parasitic organisms endowed with a life of their own relative to the diseased body. [6, 10, 260

Koch's Postulates (Step 1)

The purported infectious agent must be present in every case of the disease. [8, 261

Koch's Postulates (Step 2)

The purported infectious agent must be isolated and grown in pure culture from the diseased organism. [8, 261]

Koch's Postulates (Step 3)

When healthy hosts are inoculated with the pure culture of the purported agent, they must develop exactly the same signs and symptoms of the disease. [8, 261]

Koch's Postulates (Step 4)

The purported agent must be re-isolated from the newly infected host and identified as exactly the same as the original agent. [8, 261]

Koch's Postulates Limit

They cannot be used for many human diseases; scientists must instead rely on animal hosts to satisfy these criteria. [261]

Ignaz Semmelweis

Discovered that student doctors going from autopsies to deliveries caused 3x higher rates of puerperal (childbed) fever than midwives; pioneered chlorine handwashing; was tragically rejected by the medical establishment and died in an insane asylum. [13, 264]

Joseph Lister

Followed Pasteur's work and pioneered the disinfection of wounds and surgical equipment with carbolic acid (phenol) to develop antiseptic surgery. [13, 264]

Florence Nightingale

Founded medical statistics and professional nursing; used graphical visualization during the Crimean War to show that more soldiers died from disease than from combat wounds. [14, 264]

Zymotic Causes

Nightingale's historical term for diseases (represented by gray areas in her mortality graphs), corresponding to modern infectious diseases. [14, 264]

Ilya Metchnikoff

Discovered phagocytes (cells that engulf and digest pathogens) in starfish embryos, pioneering the field of cellular immunology. [17, 265]

Ehrlich & von Behring

Developed the first antiserum (antibodies) to protect against diphtheria; Ehrlich also pioneered the concepts of chemotherapy. [17, 18, 265]

Most Abundant Elements in Body (Ranked)

1. Carbon (the single most important element in the body), 2. Hydrogen, 3. Nitrogen (essential for amino acids, proteins, and DNA), 4. Oxygen, 5. Phosphorus, 6. Sulfur (CHNOPS). [48, 281, 282]

Fluorine-18 (18F)

An unstable radioisotope with a half-life of 110 minutes, used in PET scans for cancer patients. [281]

Banana Equivalent Dose (BED)

A tiny unit of radiation exposure (~100 nanosieverts or 1 nanorem) representing the radiation absorbed from eating one banana. [281]

Water's Unique Properties

Polarity (hydrophilic vs. hydrophobic), cohesiveness/surface tension, adhesiveness, high heat capacity (1 calorie/g/C), and acts as a universal solvent. [48, 58]

pH Calculation & Scale

pH = -log10[H+]; a logarithmic scale where each change of 1 pH unit represents a 10-fold change in hydrogen ion concentration (e.g., pH 7 to 5 represents a 100-fold increase). [49, 59]

Crystal Violet, Iodine, Alcohol, Safranin

The Gram stain reagents: Crystal Violet (primary stain), Iodine (mordant), Alcohol (decolorizer), and Safranin (counter-stain). [79, 109]

Peptidoglycan (Murein)

A structural polymer unique to bacterial cell walls, consisting of sugar chains (alternating NAM and NAG) cross-linked by short chains of amino acids; cross-linking is blocked by penicillin. [107]

Gram-Positive Cell Wall

Characterized by a relatively thick layer of peptidoglycan (around 30 layers) and teichoic acid molecules sticking out above the surface. [112]

Gram-Negative Cell Wall

Characterized by a very thin layer of peptidoglycan covered by an outer membrane containing Lipopolysaccharide (LPS) and porins, with a periplasmic space in between. [115]

Lipopolysaccharide (LPS)

An endotoxin in the outer membrane of Gram-negative bacteria; recognized by body defenses and made of three parts: lipid A, core polysaccharide, and O antigen. [115]

Bacterial Endospore

A highly resistant, dormant stage containing a core with DNA, ribosomes, dipicolinic acid, and calcium (Ca++) to survive harsh conditions. [129]

Eukaryotic Cytoskeleton Elements

1. Microtubules (tubulin; rigid skeleton/railway), 2. Microfilaments (actin; shape/pseudopodia/phagocytosis), 3. Intermediate filaments (solid threads; hold structures in place/tension monitoring). [145, 151, 157]

Endosymbiotic Theory

The theory that mitochondria and chloroplasts arose when a phagocytic eukaryotic ancestor engulfed a free-living bacterium. Evidence includes their own double membranes, circular DNA, and 70s ribosomes. [160, 165]

Symbiosis Types

Mutualism (both benefit), Commensalism (one benefits, one is unaffected), and Parasitism (one benefits at host's expense/harm). [23, 267]

Normal Flora Protection

Protects the host via competitive exclusion: blocking attachment sites, consuming nutrients (like iron), and producing natural antimicrobials. [23, 267]

Bacterial Fingerprints

The concept that every individual has a unique normal flora composition, which can link them to crime scenes or specific cultures. [23, 267]

Primary vs. Opportunistic Pathogen

Primary: infects and causes disease in healthy individuals. Opportunistic: causes disease only when host immune defenses are weakened. [32, 271]

Virulence Indicators (LD50 vs. ID50)

LD50 (Lethal Dose 50%): the number of microbes required to kill 50% of hosts. ID50 (Infectious Dose 50%): the number of microbes required to infect 50% of hosts. Lower numbers mean higher virulence. [32, 272]

R0 Value (Reproduction Number)

The average number of naive people a single sick person can infect. If R0 is less than 1, an epidemic is mathematically impossible. [32, 271, 272]

Pathogenicity Islands

Distinct gene clusters in a bacterial chromosome acquired via horizontal gene transfer that contain multiple virulence factors/toxin genes. [32, 272]

Course of Disease: Incubation Period

The consecutive first phase of infection with absolutely no signs or symptoms; the pathogen is colonizing and multiplying. [32, 273]

Course of Disease: Prodromal Phase

The brief phase following incubation, marked by vague, non-specific symptoms (like a 'scratchy throat') caused by the body's initial inflammatory response. [32, 273]

Fomite

An inanimate object or surface (e.g., doorknob, bedding) that can harbor and transmit infectious agents. [38, 274]

Vector Transmission Types

Horizontal transmission: spreading to a neighbor/peer. Vertical transmission: spreading from mother to offspring (e.g., across placenta/breast milk). [38, 274]

Rabies Virus

Enters via saliva/bite, multiplies in muscle cells, travels along neuronal axons to the brain, forms diagnostic Negri bodies, and causes fatal encephalitis. [182, 256]

Rabies Prevention (PEP)

Post-Exposure Prophylaxis: immediate vaccine and immunoglobulin shots (5 vaccine doses on days 0, 3, 7, 14, 28) following a bite. [183, 257]

Smallpox Virus (Variolavirus)

An enveloped, double-stranded DNA virus in the orthopoxvirus family; split into variola major (30-35% mortality) and variola minor (1% mortality). [196, 263]

Smallpox Transmission & Rash

Enters via respiratory tract, replicates in lymph nodes, causes deep-seated, hard pustules ('BBs'), and is contagious until the last scab falls off. [193, 196, 262, 263]

Bubonic Plague Causative Agent

Yersinia pestis; a Gram-negative rod bacterium closely related to E. coli. [209, 270]

Yersinia pestis Pathogenesis

Forms a starving midgut biofilm in fleas, inducing frequent host biting (regurgitation into wound); reproduces inside phagocytes, then extracellularly in lymph nodes. [209, 270]

Plague Types & Buboes

Classic bubonic: flea bite, causes agonizingly swollen lymph nodes (buboes). Septicemic: black necrotic tissue ('Black Death'). Pneumonic: respiratory, highly contagious and rapid. [206, 207, 269]

Malaria Parasite & Vector

Caused by Plasmodium spp. (single-celled eukaryotic protozoa); transmitted by female Anopheles mosquitoes. [216, 225, 278]

Malaria Pathogenesis & Attacks

Sporozoites multiply in the liver, release merozoites to infect red blood cells (RBCs); synchronous rupture of RBCs releases cell debris and cytokines, triggering cyclical fever/chills. [225, 230, 278, 279]

Ebola Virus

An enveloped, single-stranded, negative-sense RNA virus causing severe hemorrhagic fever. [247]

Ebola Pathogenesis

Transmitted via direct fluid contact; attacks endothelial cells (leading to bleeding and hypovolemic shock) and phagocytes (weakening the immune response). [247]

Pathogen

An infectious, disease-causing agent or microorganism

primary pathogen

infects a perfectly healthy individual, causing them to suddenly become sick

Opportunistic Pathogen

An infectious agent that typically does not cause disease in a healthy host, but takes advantage of a host with an already weakened or "low" immune system, causing a secondary infection or issue in the body

Infectious Dose (ID_50)

The specific number of pathogens or organisms required to successfully establish an infection in 50% of exposed host subjects, metric of communicability—it measures how easily a disease colonizes and spreads

Pathogenicity Island

A distinct cluster of virulence genes within a microorganism’s genome (the "sea of genes") that was acquired from another organism via horizontal gene transfer

Prebiotic

A prebiotic is a non-living, non-digestible food ingredient (typically dietary fiber) that acts as "food" to stimulate the growth and activity of the beneficial normal flora already living in your gut (Ilya Metchnikoff)

Probiotic

A probiotic is a preparation of live, beneficial microorganisms (such as certain species of Lactobacillus or Bifidobacteria) that are administered to a host to actively improve health, regulate the immune system, or restore normal flora (skin/oral treatments, Mechnikov, and gut health)

Acute Infection

An infection characterized by a rapid onset, a sharp peak in severity (known as the "acme"), and a relatively quick resolution. Your notes describe it as an illness that "comes and goes, rapid, has a peak and then goes away"

Latent Infection

An infection where the host develops the disease, recovers (as the pathogen goes dormant or "silent"), and then suddenly experiences a recurrence where the disease comes back and hits even worse. Your slides note this pattern is common in viral infections and diseases like epidemic typhus

Sequelae

Pathological conditions, chronic symptoms, or physical damage left behind in the body as a direct result of a disease after the acute infection itself has cleared (occurring after convalescence)

Virulence Factor

any structural or chemical characteristic of a pathogen—specifically the proteins it produces—that enables it to invade the host, cause damage, and determine "how sick" it makes you

Disease

A pathological process that causes physical damage to tissues or alters normal physiological function in the body. It is clinically identified and diagnosed by a specific set of signs and symptoms known as a syndrome

Infectious Disease

A disease specifically caused by the actions and colonization of microorganisms. Infectious diseases are categorized into communicable (diseases that are contagious and can be transmitted from person to person) and non-communicable

Pathogenesis

The step-by-step biological process of how and why physiology is altered to cause a disease. It outlines the underlying physiological mechanism and progression of the disease inside the body

Epidemiology

The scientific study of how diseases are transmitted, how they spread, and who gets them within a population

Intoxication

A non-infectious disease or physiological disturbance that is triggered by the toxic action of microorganisms or the ingestion of microbial toxins, rather than an active infection by the living pathogen itself

Theory of Spontaneous Generation

the historical, obsolete theory asserting that living organisms can spontaneously arise directly from non-living or decaying organic matter. This theory was formally disproved and refuted by early microbiologists including Spallanzani, Pasteur, and Tyndall

Germ Theory of Disease

The foundational scientific theory, proposed by Friedrich Henle in 1840, stating that contagions are not gaseous vapors or chemical imbalances, but are living, organic, parasitic microorganisms endowed with their own lives that actively invade a host. Pasteur supported this theory by proving microbes cause spoilage and silkworm disease, and Robert Koch definitively established it by linking specific bacteria to anthrax and tuberculosis

Emerging Infectious Diseases

New, evolving, or geographically expanding infectious diseases whose incidence in humans has significantly increased. This rise is driven by modern factors such as microbial evolution (like antibiotic resistance), changing human behavior and technology (such as day-care centers or contact lenses), societal breakdowns, population growth, and climate change (which expands the range of host animals and insect vectors like mosquitoes)

Symbiosis

A close, physical relationship where microorganisms live inside or on a host organism. Symbiosis is divided into three distinct ecological interactions

Mutualism

A cooperative relationship where both the host and the microorganism benefit

Commensalism

A neutral relationship where one organism benefits while the other is unaffected

Parasitism

A harmful relationship where the microorganism benefits at the physical expense and detriment of the host

Normal Flora

The diverse, highly individualized populations of non-harmful microorganisms (bacteria, fungi, and yeast) that naturally reside on and within the human body. They protect the host through competitive exclusion by physically blocking attachment sites, starving out pathogens by consuming available nutrients (such as iron), and directly producing toxic antimicrobials. They also help regulate gut health, train the immune system, and aid in early development