21. Principles of Disease

Given that pseudomonads are present in almost every moist environment, why do they cause less disease than other, less prevalent Gram-negative bacteria?

Although an effective vaccine is available to eradicate pertussis in the United States, why has the number of reported cases increased since the 1970s?

What two illnesses can be caused by Legionella pneumophila?

Label the following drawing using these words: adhesin, exotoxin, H antigens, hemolysin, iron-binding protein, K antigens, outer membrane (with common antigen, lipid A, and O antigen), fimbria, plasmid virulence genes, type III secretion system.

Shown is a MacConkey agar plate. Describe the Gram reaction and lactose fermentation of the two different bacteria shown.

A physician prescribes fluid replacement to treat a patient with diarrhea. Although tests showed that a pathogenic enteric bacterium was the cause of the intestinal distress, an antimicrobial drug was not prescribed; why not?

Distinguish among the pathogenicity of coliforms, noncoliforms, and truly pathogenic enteric bacteria.

Statistics show that meningococcal diseases are more frequent in college dormitories and military barracks than in the population at large. Suggest an explanation of this observation.

Why do nurses place antimicrobial agents in babies’ eyes at birth?

What attribute of Coxiella burnetii enables it to survive desiccation and heat for an extended time?

What virulence factors allow Gram-negative anaerobes to cause disease?

What single biochemical test result distinguishes gamma-proteobacteria in the family Enterobacteriaceae from gammaproteobacteria in the family Pasteurellaceae?

Most human infections caused by species of Rickettsia

a. are acquired from fomites

b. could be prevented by hand washing

c. are transmitted via vectors

d. are sexually transmitted

The bacterium that causes spotted fever rickettsiosis (RMSF) is more likely to infect a human

a. if an infected tick feeds for several hours

b. when an infected tick initially penetrates the skin

c. when contaminated tick feces dry and become airborne

d. if the human is exposed to rodent feces containing the bacterium

The most severe rickettsial illness is caused by.

a. Rickettsia typhi

b. Rickettsia rickettsii

c. Orientia tsutsugamushi

d. Ehrlichia chaffeensis