MCQs on Gram Positive, Spore Forming Bacilli: Medical Microbiology

              Multiple Choice Questions on Gram-Positive, Spore-Forming bacilli (Rods)
Bacillus spp                                           Clostridium spp

1) All of the following are the cultural characteristics of Bacilli spp, Except:
a) Anaerobes
b) Gram-positive
c) Spore-forming
d) Ubiquitous

2) Which one of the following Bacillus spp is Not commonly isolated pathogenic bacteria?
a) Bacillus cereus
b) Bacillus thuringiensis
c) Bacillus thermophilus
d) Bacillus anthracis

3) commonly found in soil and is an insect pathogen that can infect humans. It is often used in the production of insecticidal products.
a) thuringiensis
b) subtilis
c) anthracis
d) cereus

4) Most of the species of Bacilli and Clostridia are..........................., which means they obtain their nutrients from dead or organic matter.
a) Parasites
b) Saprophytes
c) Symbiotic
d) Mutualistic

5) Bacillus anthracis is a medically important spore-forming rod that may cause the disease "anthrax" in animals and humans. 
What are the two important virulence factors of the bacteria?
a) Capsule and enterotoxins
b) Exotoxins and enterotoxins
c) Endotoxins and capsule
d) Capsule and exotoxins

6) Bacillus cereus causes two types of foodborne intoxications, known as the emetic type and diarrheal type of infections. 
Which of the following is the approximate time period for the symptoms to appear after the ingestion of contaminated food?
a) 1-12 hours
b) 1-2 days
c) 1-5 hours
d) 1-24 hours

7) Bacillus… a common laboratory contaminant and is used for sterility testing. 
It is an endospore-forming bacteria and resistant to extreme environmental conditions.
a) subtilis
b) thermophilus
c) cereus
d) agalactiae

8) Which of the following species of Clostridia do not have flagella, but rapidly grow on nutrient media and mimic the growth of motile organisms?
a) Clostridium botulinum
b) Clostridium perfringens
c) Clostridium tetani
d) Clostridium difficile

9) Select the correct answers, other than food poisoning what other clinically important types of diseases are caused by Clostridium perfringens?
a) Gas gangrene
b) Impetigo
c) Cellulitis
d) Toxic shock syndrome

10) The AVA BioThrax is the FDA approved vaccine for..........................
a) Bacillus cereus
b) Clostridium tetani
c) Bacillus anthrax
d) Bacillus substilis

11) The microscopic identification of the shape and position of spores in a bacteria is a routine laboratory identification method. 
Clostridium perfringens forms subterminal spores whereas Clostridium...................... forms terminal spores.
a) tetani
b) botulinum
c) cereus
d) None of the above

12) .........................can cause infections in humans through a puncture wound and ultimately enter the central nervous system by releasing a potent toxin known as neurotoxins.
This toxin can block the release of neurotransmitters and result in cramping of muscles, causing loc jaw and other muscle-related spasms.
a) Bacillus anthracis
b) Clostridium botulinum
c) Clostridium tetani
d) Bacillus subtilis

13) Which is the most common food associated with infant botulism?
a) Maple syrup
b) Honey
c) Canned baby food
d) Corn syrup

14) Name the most potent toxin produced by Clostridium botulinum and C.tetani
a) Aflatoxin
b) Exotoxins
c) Cytotoxin
d) Neurotoxin

15) Bacillus cereus the intestines and cause foodborne illness in humans
a) Cytotoxins
b) Neurotoxins
c) Enterotoxins
d) Pneumolysin

16) All of the following statements about Bacillus anthracis are true, EXCEPT
a) Form hemolytic colonies on blood agar
b) Causes severe infections in animals
c) A non-motile gram-positive rod
d) It consists of the capsule

17) Which of the following is the correct general characteristic of Clostridia spp?
a) Grows well in Nutrient agar
b) Produce alpha-hemolytic colonies
c) Grows in aerobic conditions
d) Produces neurotoxins

18) Clostridium botulinum-associated foodborne illness may occur within 18-24 hours of ingestion of a food containing the bacterial toxin. 
Which of the following are NOT the common symptoms of the illness?
a) Poor vision
b) Fever
c) Difficulty swallowing
d) Bulbar paralysis

19) All of the following are the preventive measures for 'Tetanus', EXCEPT
a) Active immunization of toxoids
b) Prophylactic use of antitoxin
c) Administration of Bacitracin
d) All of the above

20) Clostridium perfringens toxins are released only after it enters the host cell through wounds or the gastrointestinal tract.
Which of the following enzyme produced by the bacteria is also known as alpha-toxin that can damage the cell membranes and result in 'hemolysis' and tissue destruction?
a) Lecithinase
b) Enterotoxin
c) Alpha
d) Beta

Multiple Choice Answers
2-c)Bacillus thermophilus
5-d)Capsule and exotoxins
6-c)1-5 hours
8-b)Clostridium perfringens
9-a)Gas gangrene, and c) Cellulitis
10-c) Bacillus anthrax
12- c)Clostridium tetani
15-c) Enterotoxins
16-a)Form hemolytic colonies on blood agar
17-d) Produces neurotoxins
19-c)Administration of Bacitracin
20-a) Lecithinase


  1. great set of questions to test the knowledge in this area

  2. Best of best but on diffinition is short so reason of answer explain

    1. Thank you very much, I will soon include explanation with the answers


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