Bacillus cereus

Bacillus cereus

Q. 1 Which of the following pathogens are associated with watery diarrhea after an incubation period of 8 to 14 hours?
 A Rotavirus and Norwalk virus
 B Shigella and Salmonella
 C S. aureus and Bacillus cereus
 D Bacillus cereus and Clostridium perfringens
Q. 1 Which of the following pathogens are associated with watery diarrhea after an incubation period of 8 to 14 hours?
 A Rotavirus and Norwalk virus
 B Shigella and Salmonella
 C S. aureus and Bacillus cereus
 D Bacillus cereus and Clostridium perfringens
Ans. D

Explanation:

Bacillus  cereus  and Clostridium perfringens

Bacillus cereus strains can produce two different toxins: a heat stable toxin that can lead to an illness after 2 to 7 hours and a heat-labile toxin that causes disease   manifestations   8   to   14   hours   after ingestion.  The  syndrome  of  Clostridium perfringens diarrhea usually occurs 8 to 14 hours after ingestion of the preformed toxin.


Q. 2 Shortest incubation period is for which food poisoning:
 A Staphylococcus aureus
 B Bacillus cereus
 C Salmonellosis
 D Vibrio cholera
Q. 2 Shortest incubation period is for which food poisoning:
 A Staphylococcus aureus
 B Bacillus cereus
 C Salmonellosis
 D Vibrio cholera
Ans. B

Explanation:

Bacillus cereus


Q. 3

A child developed symptoms of food poisoning after 4 hours of ingestion of fried rice. Bacillus cereus was suspected. Which among the following is TRUE about the symptoms of Bacillus cereus food poisoning in this case?

 A

Absence of vomiting

 B

Absence of diarrhea

 C

Presence of abdominal pain

 D

Presence of fever

Q. 3

A child developed symptoms of food poisoning after 4 hours of ingestion of fried rice. Bacillus cereus was suspected. Which among the following is TRUE about the symptoms of Bacillus cereus food poisoning in this case?

 A

Absence of vomiting

 B

Absence of diarrhea

 C

Presence of abdominal pain

 D

Presence of fever

Ans. C

Explanation:

Here are two distinct types of food poisoning caused by Bacillus cereus: 

  • One has a short incubation period (4 hours); heat-stable toxin is the cause; consists primarily of nausea and vomiting, mild diarrhea, similar to staphylococcal food poisoning; 
  • Other has a long incubation period (18 hours); heat-labile enterotoxin is the cause; features include watery, nonbloody diarrhea, abdominal cramps, resembling clostridial gastroenteritis.
Also know:
  • Bacillus cereus, a gram-positive, spore-forming bacillus.
  • The organisms that produce the vomiting syndrome have largely been associated with ingestion of rice, notably fried rice.
  • The spores germinate and toxin is produced causing symptoms.
  • The organisms that produce the diarrheal syndrome have been associated with contaminated meats, sauces, and dairy products.
 
Ref: Levinson W. (2012). Chapter 17. Gram-Positive Rods. In W. Levinson (Ed), Review of Medical Microbiology & Immunology, 12e.

Q. 4

Food poisoning has occured due to ingestion of contaminated fried rice, most likely organism –

 A

Staph aureus

 B

Bacillus cereus 

 C

Vibrio parahemolyticus 

 D

Yersinia

Q. 4

Food poisoning has occured due to ingestion of contaminated fried rice, most likely organism –

 A

Staph aureus

 B

Bacillus cereus 

 C

Vibrio parahemolyticus 

 D

Yersinia

Ans. B

Explanation:

Ans. is ‘b’ i.e., Bacillus cereus 

Bacillus cereus

.    It is an important cause of food poisoning.

.  Gram positive

 Motile by peritrichous flagella

.   Spore forming

.  Culture media – Mannitol – egg yolk – Phenol-red polymyxin agar (MYPA)


Q. 5

Incubation period for B. cereus –

 A

1-6 hrs

 B

8-16 hrs

 C

24 hrs

 D

a and b

Q. 5

Incubation period for B. cereus –

 A

1-6 hrs

 B

8-16 hrs

 C

24 hrs

 D

a and b

Ans. D

Explanation:

Ans. is. ‘a’ i.e., 1-6 hrs & ‘b’ i.e., 8-16 hrs 

.                              Incubation period of emetic type of food poisoning                —>    1-5 hours

.                              Incubation period of diarrheal type of food poisoning            —> 8-16 hours


Q. 6

Characteristic of Bacillus cereus food poisoning is‑

 A

Presence of fever

 B

Presence of pain in abdomen

 C

Absence of vomiting

 D

Absence of diarrhoea

Q. 6

Characteristic of Bacillus cereus food poisoning is‑

 A

Presence of fever

 B

Presence of pain in abdomen

 C

Absence of vomiting

 D

Absence of diarrhoea

Ans. B

Explanation:

Ans. is ‘b’ i.e., Presence of pain in abdomen 

.  Bacillus cereus causes two types of food poisoning :-

i)        Emetic type :- characterised by nausea, vomiting and diarrhoea

ii)      Diarrhoea’ type :- characterised by abdominal cramps and diarrhoea.


Q. 7

Non invasive diarrhea is caused by:

 A

Shigella

 B

B. Cereus

 C

Salmonella

 D

Y. enterocolitica

Q. 7

Non invasive diarrhea is caused by:

 A

Shigella

 B

B. Cereus

 C

Salmonella

 D

Y. enterocolitica

Ans. B

Explanation:

Answer is B (B. cereus)

Bacillus cereus causes non invasive diarrhea due to preformed enterotoxins Shigella, Salmonella and Y. enterocolitica are causes of invasive diarrhea.

 

 


Q. 8

A person has episodes of vomiting 6 hrs after consuming milk. Organism responsible for this may be:

March 2009

 A

Clostridium perfringenes

 B

Bacillus cereus

 C

Salmonella typhi

 D

Staphylococcus

Q. 8

A person has episodes of vomiting 6 hrs after consuming milk. Organism responsible for this may be:

March 2009

 A

Clostridium perfringenes

 B

Bacillus cereus

 C

Salmonella typhi

 D

Staphylococcus

Ans. B

Explanation:

Ans. B: Bacillus cereus and D: Staphylococcus

Incubation period of food poisoning due to:

  • Clostridium perfringenes: 6-24 hours
  • Bacillus cereus-It produces atleast 2 distinct enterotoxins. One, the emetic form with a short incubation period (1-6 hours) characterized by predominantly upper gastrointestinal tract symptoms, rather like staphylococcal food poisoning. The other, the diarrheal form, with a longer incubation period (12-24 hours) characterized by predominantly lower intestinal symptoms like clostridium perfringenes food poisoning. The toxins are preformed and stable.
  • Salmonella typhi- 12-24 hours
  • Staphylococcus- 1-6 hours. The incubation is short because of preformed toxins.


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