Should sputum isolates of Haemophilus influenzae be serotyped?
In a patient with pneumonia, sputum culture revealed ampicillin-resistant Haemophilus influenzae, type b. Although nontypable H influenzae is a normal inhabitant of the upper respiratory tract and should be considered normal flora, typable H influenzae is found in less than 5% of healthy persons. Although only 1.8% of sputum cultures reveal typable H influenzae, these strains account for 98.3% of isolates from blood cultures of patients with pneumonia due to H influenzae. Serotyping of sputum isolates is recommended in patients with pneumonia to separate pathogenic typable strains from nonpathogenic nontypable strains.
