Gram-Negative Bacilli and Spirochetes of Medical Importance

Vocabulary-style flashcards covering the characteristics, virulence factors, and diseases associated with Gram-negative bacilli, enterics, spirochetes, and other medical pathogens.

Lipopolysaccharides (LPS)

An endotoxin located in the outer membrane of Gram-negative bacteria that is released when cells lyse; it can cause fever, blood coagulation, circulation failure, hypotension, and shock.

Pseudomonas aeruginosa

A highly adaptable Gram-negative aerobic bacillus found in soil and water that is a common cause of opportunistic infections in compromised hosts, such as those with severe burns or cystic fibrosis.

Pyocyanin

A blue-green or greenish-yellow pigment produced by Pseudomonas aeruginosa that causes tissue exudates to appear as "blue pus" and can fluoresce.

Bordetella pertussis

A small, encapsulated coccobacillus that causes whooping cough, a communicable childhood respiratory syndrome characterized by fits of hacking coughs followed by a deep "whoop" inhalation.

Legionella

A Gram-negative bacillus first associated with a 1976 pneumonia outbreak among American Legion members; it was traced to contaminated air-conditioning vents.

Enterics

A large group of Gram-negative, regular straight rods that ferment glucose, reduce nitrate, and are oxidase-negative; they are a major cause of diarrheal illnesses worldwide.

Coliforms

A sub-group of Enterobacteriaceae that rapidly ferment lactose.

H antigen

A bacterial surface antigen associated with the flagella.

K antigen

A bacterial surface antigen associated with the capsule or fimbriae.

O antigen

A bacterial surface antigen associated with the Lipopolysaccharide (LPS) of the outer membrane.

Enterohemorrhagic E. coli (EHEC)

Strains of E. coli, such as O157:H7, that cause hemorrhagic colitis and kidney damage by producing a shiga toxin acquired from Shigella.

Enterotoxigenic E. coli (ETEC)

E. coli that causes severe diarrheal illness via exotoxins that stimulate fluid secretion, similar to the mechanism of cholera.

Enteroinvasive E. coli (EIEC)

E. coli that causes inflammatory disease involving invasion and ulceration of the large intestine mucosa, similar to Shigella dysentery.

Enteroaggregative E. coli (EAEC)

E. coli that aggregates and colonizes the intestinal mucosa, releasing toxins that induce inflammation and cause pediatric diarrhea.

Klebsiella pneumoniae

A Gram-negative bacterium with a heavy capsule that produces mucoid colonies and causes chronic lung infections and nosocomial pneumonia.

Salmonella Typhi

The serotype of Salmonella enterica responsible for typhoid fever, which spreads through contaminated food or water and can be carried by asymptomatic humans.

Shigellosis

An illness caused by Shigella characterized by fever, nausea, cramps, and watery bloody stool, often spread in crowded conditions with poor sanitation.

Yersinia pestis

The causative agent of the plague, a Gram-negative rod with virulence factors including a capsule, coagulase, and endotoxin; it is typically transmitted from rats to humans via fleas.

Spirochetes

A group of bacteria with a general spiral morphology and endoflagella located in the periplasmic space, including genera such as Treponema and Borrelia.

Treponema pallidum

The spirochete responsible for syphilis, an STD; it uses a hooked tip to bind to epithelial cells.

Borrelia burgdorferi

The spirochete that causes Lyme disease, transmitted to humans primarily by ticks of the genus Ixodes.

Erythema migrans

A red, bull’s-eye-shaped rash that occurs in $70\%$ to $80\%$ of Lyme disease cases at the site of the tick bite.

Vibrio cholerae

A Gram-negative curved bacterium that causes cholera, characterized by profuse water and electrolyte loss due to the action of cholera toxin (CT).

Cholera toxin (CT)

An enterotoxin that binds to intestinal receptors and disrupts cell physiology, causing cells to shed large amounts of electrolytes into the intestine.

Helicobacter pylori

A gastric pathogen that thrives in stomach acid and is a major cause of ulcers by boring through the stomach tissue.