Inhibition of Haemophilus influenzae adherence to buccal epithelial cells by cefuroxime.

We studied the effect of subinhibitory concentrations of cefuroxime on the capacity of Haemophilus influenzae to adhere to buccal epithelial cells (BEC). Two encapsulated strains (serotype b) and two nonencapsulated, nontypable strains were studied. All four strains adhered strongly to BEC, with indices (mean number of bacteria adhering to a single BEC) ranging from 19 to 48. Subinhibitory concentrations of cefuroxime (serial dilutions from MIC/2 to MIC/32) were added to cultures in tryptic soy broth and their effect on adherence was tested after 18 h incubation at 37 degrees C. Adherence was diminished by more than 50% by concentrations of cefuroxime ranging from MIC/2 to MIC/8 and varied according to the strain studied. These results show that the adherence of H. influenzae to BEC is inhibited by subinhibitory concentrations of cefuroxime.