INTERACTION OF SUBMINIMAL INHIBITORY CONCENTRATIONS OF CLINDAMYCIN AND ESCHERICHIA-COLI - EFFECTS ON ADHESION AND POLYMORPHONUCLEAR LEUKOCYTE FUNCTION

Subinhibitory concentrations (sub-MIC [minimum inhibitory concentrations]) of clindamycin interfered with the adhesion in E. coli to buccal epithelial cells and promoted phagocytosis and killing of this organism by human polymorphonuclear leukocytes (PMNL). Adherence of E. coli grown in the presence of clindamycin, at concentrations of 2-32 mg/l, varied from 21.1 .+-. 7.4-25.8 .+-. 7.8 bacteria/epithelial cell (EC) (mean .+-. SD) as compared with 58.3 .+-. 10.3/EC when the organism was cultured in the absence of the antibiotic (P < 0.01). The number of phagocytosed bacteria/200 PMNL increased from 166.1 .+-. 36.6 when E. coli was grown in medium 199 containing no antibiotic, to 289.3 .+-. 56.4 (P < 0.01) when the organism was preincubated with 4 mg/l of clindamycin. The same concentration of clindamycin also increased the percentage of phagocytosed bacteria killed by the PMNL from 42.0 .+-. 9.0% to 63.7 .+-. 11.2% (P < 0.01). Thus, sub-MIC of clindamycin enhance host defense mechanisms against E. coli.