Effect of ampicillin, cefmetazole and minocycline on the adherence of Branhamella catarrhalis to pharyngeal epithelial cells.

Using pharyngeal epithelial cells from a healthy adult and eight strains of Branhamella catarrhalis (B. catarrhalis) isolated from eight patients with respiratory infection the effect of subminimal inhibitory concentrations of cefmetazole, ampicillin and minocycline on adherence was examined. Cefmetazole-treated bacterial attachment (44 +/- 28; mean +/- S.D.) decreased significantly (p less than 0.05) compared to the control (84 +/- 27). Statistically no significant difference in adherence was found between ampicillin-treated bacteria (63 +/- 36) and the control (95 +/- 40) or minocycline-treated bacteria (91 +/- 39) and the control (109 +/- 40). Large bacteria was observed after cefmetazole and ampicillin treatment. In addition to diplococci, tetrads were observed after cefmetazole treatment. Significant correlation between the MICs and adherence ability was not found. The results suggests that these three antibiotics were not responsible for the increase in B. catarrhalis infection by increasing adherence ability.