Question
A 3-year-old male experiences several episodes of otitis media. Middle ear exudate cultures grow H. influenza although the patient’s immunizations are up-to-date. Which of the following explains H. influenza infection in this patient despite immunizations?
| A. |
No vaccine is effective against H. influenzae
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| B. |
The strains responsible for this patient’s disease produce exotoxin
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| C. |
The strains responsible for this patient’s disease do not produce a capsule
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| D. |
H. influenza infection despite immunizations means defective cellular immunity
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Show Answer
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Correct Answer � C
Explanation
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Ans. C. The strains responsible for this patient’s disease do not produce a capsule
H. influenza along with Streptococcus pneumonia is the most frequent cause of acute otitis media. This infection is primarily seen in children between 6 months and 12 years of age. More than 90% of H. influenza strains isolated from middle ear aspirates of infected children are non-typeable; the remaining 10% are H.influenzae type b. H. influenza is classified or typed, based on the antigens in its polysaccharide capsule, and strains of H. influenza that do not produce a capsule are referred to as non typable. Nontypeable H. influenzae strains are part of the upper respiratory tract normal flora, but they can also cause otitis media, sinusitis, and bronchitis in adolescents and adults, as well as children and vaccination with the H. influenza type b (Hib) vaccine, does not confer immunity to any strain except type b. It is recommended that all children receive the Hib vaccine beginning at 2 months of age as H. influenzae type b is associated with disseminated disease, pneumonia, epiglottitis and meningitis.
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