BOC MICROBIOLOGY EXAMPREP STUDY
GUIDE QUESTIONS AND CORRECT
ANSWERS COMPLETE REVIEW MATERIAL
●● MacConkey media for screening suspected cases of hemorrhagic E
coli 0157:H7 must contain:
Answer: sorbitol
●● Members of the family Enterobacteriaceae share which one of the
following characteristics?
Answer: reduce nitrate to nitrite.
●● Which one of the following genera is among the least biochemically
reactive members of the Enterobacteriaceae?
Answer: Shigella
●● Which one of the following gram negative bacilli ferments glucose
Answer: Yersinia enterocolitica
●● An organism was inoculated to a TSI tube and gave the following
reactions: alkaline slant/acid butt, H2S gas produced:
Answer: Salmonella typhimurium
, ●● A TSI tube inoculated with an organism gave the following reactions:
alkaline slant, acid butt, no H2S, no gas produced
Answer: Shigella dysenteriae
●● Which of the following organisms can grow in the small bowel and
cause diarrhea in children, traveler's diarrhea, or a severe cholera-like
syndrome through the production of enterotoxins?
Answer: Escherichia coli.
●● Shigella species characteristically are:
Answer: nonmotile.
●● A gram negative bacillus has been isolated from feces, and the
confirmed biochemical reactions fit those of Shigella. The organism
does not agglutinate in Shigella antisera. What should be done next?
Answer: Boil the organism and retest with the antisera.
●● Biochemical reactions of an organism are consistent with Shigella. A
suspension is tested in antiserum without resulting agglutination.
However, after 15 minutes of boiling, agglutination occurs in group D
antisera. The Shigella species is:
Answer: sonnei
GUIDE QUESTIONS AND CORRECT
ANSWERS COMPLETE REVIEW MATERIAL
●● MacConkey media for screening suspected cases of hemorrhagic E
coli 0157:H7 must contain:
Answer: sorbitol
●● Members of the family Enterobacteriaceae share which one of the
following characteristics?
Answer: reduce nitrate to nitrite.
●● Which one of the following genera is among the least biochemically
reactive members of the Enterobacteriaceae?
Answer: Shigella
●● Which one of the following gram negative bacilli ferments glucose
Answer: Yersinia enterocolitica
●● An organism was inoculated to a TSI tube and gave the following
reactions: alkaline slant/acid butt, H2S gas produced:
Answer: Salmonella typhimurium
, ●● A TSI tube inoculated with an organism gave the following reactions:
alkaline slant, acid butt, no H2S, no gas produced
Answer: Shigella dysenteriae
●● Which of the following organisms can grow in the small bowel and
cause diarrhea in children, traveler's diarrhea, or a severe cholera-like
syndrome through the production of enterotoxins?
Answer: Escherichia coli.
●● Shigella species characteristically are:
Answer: nonmotile.
●● A gram negative bacillus has been isolated from feces, and the
confirmed biochemical reactions fit those of Shigella. The organism
does not agglutinate in Shigella antisera. What should be done next?
Answer: Boil the organism and retest with the antisera.
●● Biochemical reactions of an organism are consistent with Shigella. A
suspension is tested in antiserum without resulting agglutination.
However, after 15 minutes of boiling, agglutination occurs in group D
antisera. The Shigella species is:
Answer: sonnei
