Epidemiology and Microbial Mechanisms of Pathogenicity

Vocabulary flashcards covering the principles of epidemiology and the mechanisms of bacterial pathogenicity, including exotoxins, endotoxins, and specific disease mechanisms.

Epidemiology

The science that studies when and where diseases occur and how they are transmitted in populations.

Epidemiologists

Professionals who determine the etiology of a disease, identify factors concerning its spread, develop control methods, and assemble data and graphs to outline disease incidence.

Descriptive Epidemiology

An approach that entails the collection of all data describing the occurrence of the disease under study; associated with John Snow.

Retrospective Epidemiology

A branch of descriptive epidemiology that backtracks to find the cause and source of a disease.

Prospective Epidemiology

An approach where a disease-free population is selected and subsequent disease experiences are recorded.

Analytical Epidemiology

The analysis of a particular disease to determine its probable cause; associated with Florence Nightingale.

Experimental Epidemiology

Research that begins with a hypothesis about a specific disease followed by experiments, such as clinical trials with control and test groups, to test said hypothesis; associated with Ignaz Semmelweis.

Case Reporting

The report of specified diseases to local, state, and governmental agencies to measure incidence and establish the chain of transmission.

Exotoxins

Proteins, often enzymes, produced inside pathogenic bacteria (mostly gram-positive) as part of growth and metabolism, then secreted into the surrounding medium during log phase.

Endotoxins

Lipid portions of lipopolysaccharides (LPS) called lipid A, located in the outer membrane of gram-negative cell walls, which are liberated when the bacteria die and the cell wall lyses.

Toxoids

Inactivated exotoxins used for vaccination, such as those for diphtheria and tetanus.

A-B Toxins

Exotoxins consisting of two polypeptides: the A component, which is the active enzyme that alters host cell function, and the B component, which is the binding component.

Membrane-disrupting toxins

Toxins that cause cell lysis by forming protein channels in the plasma membrane or disrupting the phospholipid structure.

Leukocidins

Membrane-disrupting toxins that destroy phagocytic white cells.

Hemolysins

Toxins that destroy red blood cells by forming protein channels.

Superantigens

Antigens that provoke a very intense immune response by stimulating the proliferation of T cells, which then release cytokines resulting in fever, nausea, vomiting, and diarrhea.

Genotoxins

Toxins produced by certain gram-negative bacteria (such as Helicobacter) that damage DNA, causing mutations and potentially leading to cancer.

Botulinum toxin

An A-B neurotoxin produced by Clostridium botulinum that prevents the transmission of nerve impulses, resulting in flaccid paralysis.

Tetanus toxin

A neurotoxin produced by Clostridium tetani that blocks nerve impulses to the muscle relaxation pathway, resulting in uncontrollable muscle contractions.

Limulus amebocyte lysate (LAL) test

A test used to detect endotoxins in drugs using amebocytes from the horseshoe crab (Limulus polyphemus), which lyse and form a gel-clot precipitate in the presence of endotoxin.

Septic shock

A serious condition sometimes caused by the release of high doses of cytokines when macrophages are stimulated by endotoxins.

Lipid A

The specific lipid portion of the lipopolysaccharide in gram-negative outer membranes that acts as an endotoxin.