Exam 19: Enterobacteriaceae

A gram-negative bacillus that is hydrogen sulfide (H₂S)-positive, citrate-positive, spot indole-negative, and associated with gastroenteritis in the United States is most likely:

In addition to being a group of gram-negative bacteria considered normal flora of the gastrointestinal tract of humans and animals, which one of the following also contains agents of important diseases such as gastroenteritis and enteric fevers, urinary tract infections, and bacterial pneumonia?

Which is correct for the description "alkaline slant, acid butt, no H₂S"?

For the most part, all Enterobacteriaceae are positive for which biochemical reactions?

Enterotoxigenic and enteroinvasive are terms often linked to which of the following bacterial species?

Which of correct for the description "acid slant, acid butt, no H₂S"?

Most strains of Escherichia coli can be presumptively identified on the basis of which characteristic?

On MacConkey agar, Serratia spp.would appear:

Escherichia coli would appear what color on HE agar?

A patient bitten by a flea developed a painful bubo at the site of the bite.The drug of choice for this organism is:

Of the following bacterial species, which is associated with a serious diarrheal illness with high mortality rates among some populations?

A green colony with a black center was isolated and presumptively identified as a Salmonella spp.The organism was serotyped with polyvalent antisera; however, the antisera tested negative for all antigens.What is the next course of action?

The swarming gram-negative bacillus that can be presumptively identified on the basis of a positive indole test is:

MacConkey-sorbitol agar is useful for detecting pathogenic strains of:

The major etiologic agent of urinary tract infections is:

If an organism were a glucose and lactose fermenter, the LIA reaction would be:

An organism that appears red with a black center on XLD agar is lactose-_____ and H₂S-_____.

Escherichia coli can produce a toxin similar to Shigella dysenteriae and can cause hemorrhagic colitis.What other organ does it affect?

This organism, belonging to the family Enterobacteriaceae, grows best at 25º to 30º C.Domestic and wild rats and other animals can carry this organism.What is the medium of choice?

A green colony with a black center is isolated on HE agar from a stool specimen.It is most likely which organism?