Deck 19: Enterobacteriaceae

Question 1

What organism in the genus Providencia is incriminated in nosocomial outbreaks in burn units and has been isolated from urine cultures?

A) Providencia stuartii
B) P. heimbachae
C) P. rustigianii
D) P. alcalifaciens

Answer 1

A
Similarly,P.stuartii has been incriminated in nosocomial outbreaks in burn units and has been isolated from urine cultures.P.alcalifaciens is usually found in the feces of children with diarrhea; however,its role as a cause of diarrhea has not been proved.P.rustigianii is rarely isolated,and its pathogenicity also remains unproven,whereas P.heimbachae has yet to be isolated from any clinical specimens.

Question 2

This genus has one species associated with it that has been implicated in urinary tract infections.What is the name of this species?

A) Klebsiella pneumoniae
B) Escherichia coli
C) Hafnium alvei
D) Morganella morganii

Answer 2

D
The genus Morganella currently has only one species,M.morganii,with two subspecies: M.morganii subsp.morganii and M.morganii subsp.sibonii.Neither subspecies have been implicated in diarrheal illness,but the role they play as an etiologic agent of diarrheal disease has not been fully examined.M.morganii is,however,a documented cause of urinary tract infections and has been isolated from other human body sites.

Question 3

All of the following are clinically significant isolates of the genus Enterobacter EXCEPT:

A) Enterobacter cloacae
B) E. aerogenes
C) E. sakazakii
D) E. hartmanni

Answer 3

D
Clinically significant Enterobacter spp.that have been isolated from clinical samples include E.cloacae,E.aerogenes,E.gergoviae,E.sakazakii,and E.hormaechei.

Question 4

Which of the following agars is not selective for Enterobacteriaceae?

A) Buffered charcoal yeast extract
B) MacConkey
C) Hektoen enteric
D) Xylose-lysine deoxycholate

Question 5

What are the primary antigens used in serologic grouping of salmonellae?

A) Somatic A antigen and flagellar O antigens
B) Capsular A antigen and somatic O antigen
C) Flagellar H antigen and capsular A antigen
D) Flagellar H antigen and somatic O antigen

Question 6

What is the name of the organism that has been a documented cause of nursery outbreaks of neonatal meningitis and brain abscesses?

A) Citrobacter freundii
B) C. asteroides
C) C. braakii
D) C. koseri

Question 7

The Escherichia coli serotype O157:H7 is associated with all the following EXCEPT:

A) Hemorrhagic diarrhea
B) Colitis
C) Liver damage
D) Hemolytic-uremic syndrome

Question 8

What organism presents as a pink colony with a halo on MacConkey media and a green metallic sheen on EMB?

A) Salmonella enterica
B) Proteus mirabilis
C) Escherichia coli
D) Klebsiella pneumonia

Question 9

What genus of bacteria is considered an opportunistic pathogen associated with nosocomial outbreaks?

A) Enterobacter
B) Serratia
C) Proteus
D) Escherichia

Question 10

Escherichia coli strains are associated with all the following properties EXCEPT:

A) Indole production
B) Fermentation of glucose and lactose
C) Methyl red (MR) positive, Voges-Proskauer (VP) negative
D) Can use citrate as a sole carbon source

Question 11

Which organism is the most common cause of urinary tract infections (UTIs)in humans?

A) Escherichia coli
B) Klebsiella oxytoca
C) Proteus mirabilis
D) Enterobacter cloacae

Question 12

A microbiologist is reading a stool culture and notices a very moist and mucoid pink colony on MacConkey agar.What is the most likely organism?

A) Klebsiella pneumoniae
B) Escherichia coli
C) Proteus vulgaris
D) Acinetobacter

Question 13

Where are most Salmonella serotypes found?

A) Dogs
B) Cold-blood animals (fish)
C) Cats
D) Horses

Question 14

What two bacteria produce swarming colonies on nonselective media such as sheep blood agar (SBA)?

A) Enterobacter aerogenes and Serratia marcescens
B) Proteus pannier and Klebsiella pneumoniae
C) Proteus vulgaris and Proteus mirabilis
D) Proteus mirabilis and Escherichia coli

Question 15

What substance,when produced by Salmonella spp.that cause gastroenteritis,has been implicated as a significant virulence factor?

A) Hyaluronidase
B) Protease
C) Enterotoxin
D) Endotoxin

Question 16

All of the following are categories of diarrheogenic Escherichia coli EXCEPT:

A) ETEC
B) EMEC
C) EIEC
D) EPEC

Question 17

All the following are biochemical features of Salmonella EXCEPT:

A) Lactose positive
B) Indole negative
C) Hydrogen sulfide positive
D) Voges-Proskauer (VP) negative

Question 18

All of the following are members of the Citrobacter genus EXCEPT:

A) Citrobacter freundii
B) C. diversus
C) C. asteroides
D) C. braakii

Question 19

What genus has the following characteristics: negative for urea,positive for lysine decarboxylase,positive for hydrogen sulfide,positive for indole,and does not grow on Simmon's citrate?

A) Providencia
B) Edwardsiella
C) Escherichia
D) Morganella

Question 20

The primary pathogens of the Enterobacteriaceae include all the following EXCEPT:

A) Salmonella enterica
B) Proteus mirabilis
C) Shigella spp.
D) Yersinia spp.

Question 21

Bacillary dysentery caused by this organism is marked by penetration of intestinal epithelial cells following attachment of the organisms to mucosal surfaces,local inflammation,shedding of the intestinal lining,and formation of ulcers that follow the epithelial penetration.What is this organism?

A) Enterobacter
B) Citrobacter
C) Shigella
D) Salmonella

Question 22

All of the following are characteristics of Shigella spp.EXCEPT:

A) Nonmotile
B) Urea positive
C) Hydrogen sulfide negative
D) Lysine decarboxylase negative

Question 23

What enteric organism may produce a blue-violet pigment on non-blood-containing media?

A) Kluyvera
B) Shigella
C) Ewingella
D) Cedecea

Question 24

In the carrier state,where are pathogenic salmonellae carried?

A) Gallbladder
B) Liver
C) Intestines
D) Stomach

Question 25

What organism possesses the Vi antigen?

A) Salmonella serotype Typhi
B) S. sonnei
C) Shigella sonnei
D) Citrobacter freundii

Question 26

What bacterium is the causative agent of the plague?

A) Salmonella enteritidis
B) Citrobacter freundii
C) Shigella sonnei
D) Yersinia pestis

Question 27

Why can't direct microscopy be used to provide a presumptive identification of the enteric bacteria?

A) Some members of the genus Gram stain weakly.
B) The microscopic characteristics are indistinguishable from other gram-negative bacteria
C) Some members of the genus do not decolorize well and appear gram positive.
D) Some members have very thick capsules, and these do not allow the penetration of the Gram stain.

Question 28

What disease produced by a salmonellae species is a severe form of enteric fever?

A) Pontiac fever
B) Typhoid fever
C) Undulant fever
D) Malignant fever

Question 29

Why is it that most cases of salmonella food poisoning are not treated with antibiotics?

A) The organisms are very resistant to antibiotics.
B) Antibiotics cannot reach the organisms, as they are deeply embedded in the intestinal walls.
C) Antibiotics would only kill the bacteria, then release the endotoxins into the blood, making things worse.
D) The disease is self-limiting and will subside on its own.

Question 30

All of the following are symptoms of salmonellosis that may appear 8 to 36 hours after ingestion of contaminated food EXCEPT:

A) Nausea
B) Vomiting
C) Headache
D) Watery diarrhea