Nasopharyngeal carriage of antibiotic-resistant Haemophilus influenzae in healthy children.

We selected 16 schools representing a broad socioeconomic cross-section of metropolitan Omaha and obtained nasopharyngeal cultures for Haemophilus influenzae from 1,084 healthy 4- to 7-year-old children. We found that 34.2% of the children carried nontypable strains and 2.0% carried type b strains. Carriage rates were not influenced by recent illness, family size, or number of people sharing a bedroom. The prevalence of ampicillin-resistant H influenzae in the sample population was 0.9% for nontypable strains and 0.4% for type b strains; it was not significantly different in the group of children who had recently used beta-lactam antibiotics. One child carried a nontypable strain which was resistant to both chloramphenicol and tetracycline, the first chloramphenicol-resistant H influenzae detected in Omaha. A survey of healthy children may be a useful method for projecting a community's risk of disease caused by ampicillin-resistant H influenzae. Among the nasopharyngeal isolates from healthy children, 2.7% of nontypable strains and 18.2% of type b strains were resistant to ampicillin (P less than .01). During the same five-month period in Omaha, clinical failure in the treatment of otitis media with ampicillin was uncommon and four (20.0%) of 20 cases of H influenzae type b bacteremia and meningitis were caused by ampicillin-resistant organisms.