MCQs on Haemophilus spp - gram negative coccobacilli bacteria

                         

                          Multiple Choice Question on Haemophilus spp (with a clinical case)

1) Which of these small, gram-negative coccobacillus are clinically important human pathogens?
a) Haemophilus influenzae
b) Bordetella pertussis
c) Haemophilus parainfluenzae
d) Streptococcus pyogenes

e) Brucella melitensis

2) Why should specimens suspected of containing Haemophilus spp.be inoculated to appropriate media immediately?

a) Because Haemophilus spp. are resistant to drying

b) Because Haemophilus spp. are susceptible to drying

c) Because Haemophilus spp. grow better at room temperature

d) Because Haemophilus spp. do not require media for cultivation

3) Which of the following gram-negative coccobacillus require both the X (hemin) and V (NAD) factors for its growth?
a) Neisseria gonorrhoeae
b) Bordetella pertussis
c) Streptococcus pyogenes
d) Haemophilus influenzae

4) Secondary porphyria associated with Haemophilus infections refers to:

a) A primary porphyria exacerbated by Haemophilus infections

b) The direct effects of Haemophilus bacteria on porphyrin metabolism

c) The porphyrin-related symptoms of Haemophilus infections

d) A genetic condition caused by Haemophilus bacteria

5) Which of the following bacteria is the primary cause of Chancroid?

a) Haemophilus ducreyi

b) Haemophilus influenzae 

c) Haemophilus parainfluenzae

d) Haemophilus parahaemolyticus

6) Why do most Haemophilus spp. strains not grow on 5% sheep blood agar?

a) Lack of X factor

b) Lack of NAD

c) Lack of protoporphyrin IX

d) Lack of red blood cells

7) What is the recommended method for incubating cultures of Haemophilus spp. to provide optimal growth conditions?

a) In a refrigerator at 4°C

b) In a vacuum chamber

c) In a CO2 incubator

d) In direct sunlight

8) Name the highly contagious coccobacillus that is naturally found in animals such as squirrels, mice, and rabbits?
a) Francisella tularensis
b) Haemophilus influenzae type b
c) Histoplasma capsulatum
d) Bordetella parapertussis

9) All of the following are the major virulence factors present in H. influenzae, Except?

a) Capsule
b) Neuraminidase
c) IgA protease
d) Exotoxins

e) Lipid A

10) Which of the following is Not the common culture characteristics of H. ducreyi?
a) It appears as small, gram-negative coccobacillus, when stained with Gram's stain.

b) Forms small, gray, translucent colonies with a "school of fish" or "railroad track" appearance on Chocolate agar.
c) Requires the X factor but not the V factor
d) Requires 5-10% CO2 and 35-37°C incubation temperature

11) A 4 year old girl is brought to the pediatrician's office by her parents, she had been experiencing a fever for the past two days. She had high fever ranging from 101°F to 102.5°F during this time. She had also become increasingly irritable and fussy.

The girl had a history of recurrent ear infections in the past, for which she had received antibiotics. She was up-to-date on her vaccinations, including the Haemophilus influenzae type b (Hib) vaccine.

Upon examination, the pediatrician noted the girl has fever of 102°F (38.9°C). She appeared to be in pain and was difficult to console. Her left ear revealed a bulging and erythematous tympanic membrane (eardrum), no signs of respiratory distress were observed.

Based on clinical presentation, including fever, irritability, and signs of an ear infection, the pediatrician suspected acute otitis media (AOM). AOM is an infection of the middle ear, and it can be caused by various bacteria, including Haemophilus influenzae.

Which of the following antibiotic is commonly prescribed to treat the ear infection by bacteria?

a) Amoxicillin

b) Azithromycin

c) Ciprofloxacin

d) Ceftriaxone 

12) What is a ' Quellung reaction '?
a) Direct antigen detection test

b) The bacterial motility test

c) The capsular swelling test
d) The serological antibody detection test

13) Which of the antibiotic is commonly used for the treatment of meningitis and other severe infection caused by Haemophilus spp?

a) Amoxicillin

b) Azithromycin

c) Ciprofloxacin

d) Ceftriaxone    

14) Which of the following stain is commonly used for the direct detection of Haemophilus spp in specimens that is not undetected by Gram staining?

a) Acridine orange

b) Giemsa stain

c) India ink 

d) Lactophenol blue

15) Which of the following do not prove to be helpful for the treatment of the disease "whooping cough"?
a) Cough syrups and expectorants
b) DPT vaccine
c) Macrolides
d) None of the above

16) H. parainfluenzae can grow on blood agar and requires which of the following factor for proper growth in the clinical laboratory?

a) X (hemin factor)

b) V (NAD+ factor)

c) X and V factor

d) None of the above

17) What is the most common infection associated with type b H. influenzae?

a) Conjunctivitis

b) Genital chancre

c) Arthritis

d) Meningitis

18) Haemophilus influenzae are mainly categorized into serotype and nonserotype, which of the following virulence factor is present in the serotype H.influenzae?

a) Exotoxin

b) Flagella

c) Capsule

d) Teichoic acid

19) Haemophilus influenzae type b vaccine (Hib) is a part of routine childhood immunization schedules in many countries.

What is the recommended age limit of the children to get Hib vaccine?

a) 1 to 5 year old

b) 2 months to 15 months old

c) 5 to 10 year old

d) 6 months to 5 years old

20) H.influenzae type B (HiB) is the common cause of sore throat, difficulty swallowing, drooling, stridor (noisy breathing) in young children. What is it called?

a) Epiglottitis

b) Otitis media

c) Brazilian purpuric fever

d) Lassa fever

21) Which type of specimen collection method is recommended for specimens susceptible to contamination with normal microbiota, such as lower respiratory specimens?

a) Sputum collection

b) Throat swab collection

c) Bronchoalveolar lavage

d) Blood culture collection

22) What is the optimal incubation temperature for cultures of H. ducreyi?

a) 25°C

b) 30°C

c) 33°C

d) 35°C to 37°C

23) Which of the following Haemophilus spp is not a part of normal microbiota of upper respiratory tract?

a) Haemophilus ducreyi

b) Haemophilus influenzae

c) Haemophilus parainfluenzae 

d) Haemophilus parahaemolyticus

Multiple Choice Answers with Explanation:

1- a), b), c), and e) are correct

Option d) Streptococcus pyogenes is a gram positive coccus

2- b) Because Haemophilus spp. are susceptible to drying
3- d) H. influenzae

4- b) The direct effects of Haemophilus bacteria on porphyrin metabolism. Porphyrin tests can be used to assess certain types of porphyrias associated with Haemophilus spp. infections. Haemophilus influenzae can cause porphyrin abnormalities, particularly in cases of invasive disease.

5- a) Haemophilus ducreyi. Chancroid is caused by Haemophilus ducreyi, a bacterium that primarily infects the genital area.

6-b) Lack of NAD.  Haemophilus spp. often grow best on specialized media, such as chocolate agar, which contains hemin (X factor) and NAD (V factor). These growth factors are essential for their growth, and chocolate agar provides them.

7- c) In a CO2 incubator. Haemophilus spp. are capnophilic, which means they require an increased concentration of carbon dioxide (CO2) for optimal growth. Typically, 5% to 10% CO2 is provided in the incubation environment. 

8-a)Francisella tularensis

9- d) Exotoxins. It is a extracellular toxin not found in Haemophilus spp.

10- c) Requires the X factor but not the V factor. Requires both the X factor (hemin) and the V factor (NAD, nicotinamide adenine dinucleotide) for growth.

11- a) Amoxicillin. Ampicillin or amoxicillin is often used for respiratory tract infections, ear infections, and non-invasive Haemophilus infections.

12- c) The capsule detection test. Also known as the 'Neufeld reaction' or 'capsular swelling reaction', is a laboratory test used to identify and characterize the capsules of certain bacteria.

13- d) Ceftriaxone. It used for more severe infections, such as meningitis or septicemia. 

14- a) Acridine orange. It is a fluorescent dye, useful for visualizing bacterial cells and assessing their morphology, viability, and relative abundance in a sample.

15- a) Cough syrups and expectorants

16- b) V or NAD+factor

17- d) meningitis

18- c) Capsule. Virulence factor common in H. influenzae type B (HiB) that enhances the pathogenesis into the host cells.

19- b) 2 months to 15 months old. Hib vaccine is important to prevent more severe Haemophilus influenzae type b infections.

20- a) Epiglottitis. Epiglottitis is an acute inflammation of the epiglottis, located at the base of the tongue that covers the trachea during swallowing to prevent food or liquid from entering the airway. It is often caused by bacteria such as Haemophilus influenzae type B (Hib).

21- c) Bronchoalveolar lavage. Bronchoalveolar lavage (BAL) is a medical procedure used to collect samples from the lower respiratory tract, specifically from the bronchioles and alveoli (air sacs) of the lungs. It is often used to investigate the cause of pulmonary (lung) diseases, infections, and respiratory symptoms. By collecting fluid and cells from the lower respiratory tract, healthcare providers can identify pathogens, inflammatory markers, and abnormal cell types.

22- c) 33°C

23- a) Haemophilus ducreyi. Only H. ducreyi is not part of normal human microbiota. Only found in humans during infection, and transmitted from person-to person through sexual contact.