MCQs on Vibrio spp and Aeromonas spp: (Medical Microbiology)

            Multiple Choice Questions on Cholera, Campylobacter spp, and Helicobacter spp

1) A 8 year old boy is presented to a emergency department, he has been experiencing profuse watery diarrhea and vomiting for the past 24 hours, with a suspicion of food poisoning. His parents report that they recently came back two days ago from a trip to an area with poor sanitation and limited access to clean drinking water. 
To investigate further, a stool sample with watery consistency was collected and cultured using a high-pH medium containing sodium chloride (NaCl). Colonies with a smooth and round appearance developed on the culture medium. Microscopic analysis revealed the presence of gram-negative, motile, comma-shaped bacteria.
What is the characteristic appearance of the diarrhea in cholera?
a) Bloody and foul-smelling
b) Colorless and odorless, resembling "rice water"
c) Green and frothy
d) Yellow and oily

2) What is the key diagnostic tool used to confirm cholera in the laboratory?
a) Blood culture
b) Chest X-ray
c) Stool culture on (thiosulphate bile salts sucrose agar) TCBS agar
d) Urine analysis

3)What is the most common food associated with foodborne gastroenteritis by Vibrio parahaemolyticus?
a) Chicken
b) Fish
c) Oysters
d) Rice

4) Which of the following statements is not correct about Aeromonas spp and Plesiomonas spp?
a) Both are oxidase-positive
b) They can be found in freshwater and soil
c) They are gram-negative rods
d) Grow well on TCBS (thiosulphate citrate bile salt) media

5) What antibiotics are commonly used to treat cholera?
a) Ciprofloxacin and levofloxacin
b) Doxycycline and azithromycin
c) Penicillin and amoxicillin
d) Vancomycin and metronidazole

6) Which of the following infections is typically associated with Aeromonas spp infection in humans?
a) Ear infections, wound infections
b) Gastroenteritis and wound infection   
c) Peptic ulcers
d) Periodontal diseases

7) What is the colonial characteristics of Aeromonas spp  on Blood agar and MacConkey agar?
a) Large, round, raised, opaque
b) Large, opaque and rough 
c) Small, round, raised, opaque
d) Small, convex and smooth

8) What characteristic is used to differentiate Aeromonas spp. on Aeromonas agar?
a) An almond-like odor
b) Hemolysis on blood agar
c) Production of violet pigment
d) Utilization of D-xylose

9) How can Aeromonas spp. be distinguished from Yersinia enterocolitica on modified cefsulodin-irgasan-novobiocin (CIN) agar?
a) By colony color
b) By the presence of cefsulodin
c) By the oxidase test
d) By D-xylose utilization

10) Which bacterial genera are typically beta-hemolytic on blood agar?
a. Aeromonas spp.
b. Chromobacterium violaceum
c. Yersinia enterocolitica
d. All of the above

11) Which of the following biotypes of Vibrio cholerae is prevalent in developing countries?
a) EL Tor
b) Classic
c) Biotype 0139
d) Biotype 139

12) Aeromonas hydrophila is a pathogen of fish and amphibians and is less pathogenic to humans.
Name the most common human disease associated with A. hydrophila.
a) Asthma
b) Bacterial vaginosis
c) Dysenteric gastroenteritis
d) Ear infection

13) Which of the following laboratory test is used to distinguish between pathogenic Vibrio cholerae and other non-cholera Vibrio species that helps identify V. cholerae by its ability to produce "cholera toxin." ?
a) Indole production test 
b) Lactose production test
c) The string test 
d) Venereal disease research laboratory (VDRL) test 

14) Vibrio vulnificus and V. parahaemolyticus are both gram-negative, motile bacteria that are mostly found in warm coastal areas. 
What is the common source of transmission of infection in humans?
a) Water
b) Oysters
c) Shellfish
d) All of the above

15) … less likely to cause gastroenteritis or diarrheal disease in humans.
a) Vibrio spp
b) Salmonella spp
c) Plesiomonas spp
d) Campylobacter spp

16) What preventive measures are effective in reducing the spread of cholera?
a) Access to clean drinking water and proper sanitation
b) Quarantining affected individuals
c) Mandatory use of antibiotics
d) Isolation of all water sources

17) What is the primary function of the B subunit (CTB) of cholera toxin (CT)?
a) Activating adenylate cyclase
b) Binding to host cell receptors
c) Enhancing water reabsorption
d) Inhibiting cAMP production 

18) All of the following are the general symptoms of cholera infections, except?
a) Diarrhea
b) Dehydration
c) Vomiting
d) High-grade fever

19) Which of the following is the recommended initial used treatment for cholera symptoms in developing countries like India, Nepal, and Bangladesh?
a) Antibiotics
b) Oral rehydration solution (ORS)
c) Intravenous steroids
d) Vaccination method

20) In 2022 outbreaks of cholera infections have occurred in different parts of the world such as India, Nepal, Pakistan, and some parts of Africa.
What precautions should be followed while traveling to cholera endemic regions? 
Select all the correct answers:
a)Drinking boiled water or bottled water
b)Disinfection of water by using chlorine and filter 
c)Frequent hand washing with soap and water
d)Eat only foods that are served hot and fresh

21) Select one general characteristics difference between Aeromonas spp and Vibrio spp?
a) Gram negative, facultative anaerobes
b) Oxidase and catalase positive
c) Curved, comma shaped bacilli
d) Infection in humans by consumption of contaminated water
22) Which of the following virulence factor (toxin) is not released by V. cholerae?
a) Cholera toxin (CT)
b) O1 and O139 somatic antigens
c) Zonula occludens toxin (Zot) enterotoxin
d) Diphtheria toxin

Multiple Choice Answers Review:
1-b) Colorless and odorless, resembling "rice water"

2-c) Stool culture on TCBS agar. (TCBS) agar is selective medium for Vibrio spp, The agar contains bile salts that inhibit the growth of gram-positive organisms.

3-c) Oysters
4-d) Grow well on TCBS (thiosulphate citrate bile salt) media
5- b) Doxycycline and azithromycin
6- b) Gastroenteritis and wound infection  
7- a) Large, round, raised, opaque
8- d) Utilization of D-xylose
9- c) By the oxidase test
10- d. All of the above
11- a) EL Tor
12- c) Dysenteric gastroenteritis

13- c) The string test.  The formation of a string-like or "thread" indicates the presence of the O1 somatic antigen, which is characteristic of V. cholerae
14-d) All of the above
15-c) Plesiomonas spp
16- a) Access to clean drinking water and proper sanitation
17-b) Binding to host cell receptors
18- d) High grade fever
19-b) Oral rehydration solution
20-a), b), c), and d)
21- c) Curved, comma shaped bacilli. Aeromonas spp is straight bacilli with round ends/coccobacillary
22- d) Diphtheria toxin, it is produced by Corynebacterium diphtheria


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