Carriage and Antimicrobial Susceptibility of Haemophilus influenzae Isolated from Oropharynges of Children

ABSTRACT

PURPOSE: Haemophilus influenzae, one of the normal flora of the upper respiratory tract, can cause such infections as otitis, sinusitis, pneumonia, and meningitis in children. The oropharyngeal flora has therefore mainly been analyzed as a reservoir for pathogens. This study was performed to reveal the colonization rate of H. influenzae in the upper respiratory tract, their biotypes, their antimicrobial resistance and production of beta-lactamase in healthy children. METHODS: The specimens for H. influenzae were obtained through oropharyngeal swab from 209 healthy children, younger than 5 years of age in 4 day care centers from March 1998 to June 1998. These isolates of H. influenzae were tested for their biotypes, in vitro susceptibility to seven antimicrobial agents(ampicillin, ampicillin/sulbactam, aztreonam, chloramphenicol, cefotaxime, tetracycline and trimethoprim-sulfamedoxazole) by disc diffusion method and production of beta- lactamase. RESULTS: The carriage rate of H. influenzae in the day care center children was 13.4%(28/209). Of 24 isolates, 8 isolates(33%) were biotype II and 6 isolates(25%) were biotype I. The overall rates of resistance of 15 isolates are as follows; ampicillin 46.7%, tetracycline 28.6%, trimethop rim-sulfamedoxazole 14.3%, ampicillin/sulbactam 6.7%. The prevalence of beta-lactamase producing isolates was 65.2%. All beta-lactamase producing isolates were resistant to ampicillin. The resis tance rates of beta-lactamase producing isolates to tetracycline, trimethoprim-sulfamedoxazole, and ampicillin/sulbactam were 44.4%, 25.0%, and 11.1%, respectively. CONCLUSION: Children in day care centers in Seoul have high rates of H. influenzae carriage. The antimicrobial resistance of H. influenzae from the oropharyngeal specimens of healthy children was higher than expected.