MCQs on Bordetella spp, isolation and identification, diagnosis and treatment: Medical microbiology

        MCQs on Bordetella spp, isolation and identification, diagnosis and treatment

                                     Figure: Bordetella pertussis colonies

1. A six months old child is brought to the emergency department by her parents. She has been experiencing a severe cough for the past two weeks, which has worsened recently. Her parents are concerned about her difficulty breathing and episodes of coughing fits.
The child appears to be in moderate distress. She has been experiencing paroxysms of coughing, followed by a "whooping" sound as she tries to inhale. During coughing fits, she becomes cyanotic (turns blue) due to the struggle for breath. Her parents report that she hasn't had her routine vaccinations, including the DPT (diphtheria, pertussis, tetanus) vaccine.
Upon examination, the child has mild fever (101°F) and mild tachypnea (increased respiratory rate). There is no sign of nasal congestion or a runny nose, and her lungs are clear. The characteristic whooping sound is noted during the physical examination.
A chest X-ray is performed, which shows no significant abnormalities. A nasopharyngeal swab is collected for laboratory testing to confirm the diagnosis.

Based on the clinical presentation and the laboratory results, the child is diagnosed with pertussis (whooping cough), caused by Bordetella pertussis.

What is the primary mode of transmission for pertussis?

a. Airborne transmission    

b. Bloodborne transmission

c. Foodborne transmission

d. Vector-borne transmission

2. What is the primary reason for vaccinating children against pertussis?

a. Preventing pneumonia

b. Preventing tetanus

c. Preventing chickenpox

d. Reducing the risk of transmission   

3. What antibiotic is typically used to treat Bordetella pertussis infection in children?

a. Azithromycin    

b. Ciprofloxacin

c. Doxycycline

d. Penicillin

4. In which part of the respiratory tract do B. pertussis bacteria primarily colonize?

a. Anterior nose

b. Epithelial cells in the upper respiratory tract   

c. Sputum

d. Throat

5. At what age is the first dose of DTaP vaccine typically administered to children?

a. Under 6 months   

b. 6 months

c. 2 years

d. 4-6 years

6. Which of the following specimen is commonly collected for B. pertussis culture and isolation?

a. Eyes swabs

b. Mouth swabs

c. Nasopharyngeal swabs

d. Throat swabs

7. Which of the following is NOT an acceptable transport medium for pertussis swabs?

a. Casamino acid broth

b. Cold casein hydrolysate medium

c. Nutrient agar    

d. None of the above

8. How long should transport time for pertussis specimens ideally not exceed?

a. 12 hours

b. 24 hours

c. 36 hours

d. 48 hours    

9. Which of the following agar media is considered best for the recovery of B. pertussis from nasopharyngeal swabs?

a. Bordet-Gengou agar

b. Modified Jones-Kendrick charcoal agar

c. Regan-Lowe agar     

d. Stainer-Scholte synthetic agar

10. What transport medium is commonly used for swabs in pertussis testing?

a. Blood agar

b. Chocolate agar

c. Regan-Lowe agar    

d. Sabouraud dextrose agar

11. How do young colonies of B. pertussis and B. parapertussis typically appear on culture media?

a. Large and colorful

b. Small and shiny, resembling mercury drops    

c. Smooth and flat

d. Whitish gray

12. Which of the following statements about strict human pathogen Bordetella spp (B. pertussis and B. parapertussis) is correct?

a. They are gram-positive bacteria.

b. They form spores.

c. They are facultative anaerobes.

d. They are gram-negative, non motile coccobacilli.

13. Which of the following culture medium is a potato infusion base containing glycerol and either sheep or horse blood?

a. Bordet-Gengou agar    

b. Modified Jones-Kendrick charcoal agar

c. Regan-Lowe agar

d. Stainer-Scholte synthetic medium

14. What type of pertussis vaccine was introduced in the 1950s, significantly reducing pertussis incidence in many countries?

a. Acellular pertussis vaccine (DTaP)

b. Measles, mumps, and rubella (MMR) vaccine

c. Oral polio vaccine

d. Whole-cell pertussis vaccine (DTP)

15. In which decade was the acellular pertussis vaccine (DTaP) first introduced?

a. 1950s

b. 1970s

c. 1990s

d. 2000s

16. What recent developments in pertussis prevention have occurred in the 2020s?

a. A decrease in vaccine coverage

b. A focus on booster vaccines (Tdap)

c. An increase in pertussis vaccine side effects

d. The elimination of pertussis as a public health concern

17. Which of the following is a key virulence factor produced by B. pertussis?

a. Filamentous hemagglutinin 

b. Flagellum

c. Hemolysin

d. Lipopolysaccharide (LPS)

Answers:

1. a. Airborne transmission 

2. d. Reducing the risk of transmission

3. a. Azithromycin. The macrolide agents erythromycin, clarithromycin, and azithromycin are preferred for the treatment of pertussis in persons aged >1 month. For infants aged <1 month, azithromycin is preferred.

4. b. Epithelial cells in the upper respiratory tract 

5. a. Under 6 months. For prevention against pertussis during childhood, 5 doses of diphtheria and tetanus toxoid and acellular pertussis (DTaP) vaccine at ages 2, 4, 6, 15--18 months, and 4--6 years is recommended. (source: Centers for Disease and Prevention -CDC).

6. c. Nasopharyngeal swabs

7. c. Nutrient agar  

8. d. 48 hours 

9. c. Regan-Lowe agar

10. c. Regan-Lowe agar 

11. b. Small and shiny, resembling mercury drops 

12. d. They are gram-negative, non motile coccobacilli.

13. a. Bordet-Gengou agar   

14. d. Whole-cell pertussis vaccine (DTP)

15. c. 1990s. Acellular pertussis vaccine (DTaP) developed and introduced in the 1990s to decrease side effects compared to the whole-cell vaccine.

16. b. A focus on booster vaccines (Tdap)

17. a. Filamentous hemagglutinin. It is an important toxins produced by Bordetella pertussis.

These virulence factors enable the bacterium to adhere to and colonize the respiratory tract, evade the immune system, and cause disease.