Antimicrobial sensitivity of Haemophilus influenzae isolates from bacterial conjunctivitis.

Haemophilus influenzae is one of the common bacterial pathogens which affect children. Resistance to frequently used antibiotics is becoming a significant problem in community isolates of common pathogens. A retrospective review was conducted of the serotypes and antimicrobial sensitivity of H influenzae isolates from bacterial conjunctivitis, over an 18-month period. Data on antimicrobial sensitivity (obtained by the National Committee for Clinical Laboratory Standards disk diffusion method) and beta-lactamase production, and typing results, were analysed. Ninety-nine isolates were recovered, of which 87 were typed. Most isolates were recovered from children under one year of age. Ninety-three percent were unencapsulated and biotypes I and IV were most common. H influenzae type b was recovered only twice. beta-lactamase was produced by 41% isolates while four isolates were ampicillin-resistant but did not produce beta-lactamase. All isolates were sensitive to chloramphenicol and 45% were co-trimoxazole sensitive. H influenzae is commonly isolated from bacterial conjunctivitis in Barbados and, as elsewhere, the majority of isolates are from small children and are non-encapsulated. However, there is a high prevalence of beta-lactamase production, which may serve as a reservoir for transfer to more invasive encapsulated strains of H influenzae within the oropharyngeal flora.