Nasopharyngeal carriage and antibiotic resistance of Haemophilus influenzae in healthy children.

An investigation was undertaken to determine the isolation rate and antibiotic resistance of Haemophilus influenzae from the nasopharynx of young children. The 996 subjects studied were up to 6 years of age. H. influenzae was isolated from 304 (30.5%) and strains of capsular type b from 11 (1.1%). Age, sibling status, season, respiratory infection and antibiotic therapy all influenced isolation rates. The overall prevalence of antibiotic resistance in the strains isolated was ampicillin 5.4% (all beta-lactamase producers), cefaclor 0.3%, chloramphenicol 1.3%, erythromycin 38.2%, tetracycline 1.3%, trimethoprim 5.4% and sulphamethoxazole 0%. Ampicillin resistance was more common in type b than non-capsulated strains.