Effects of Subminimal Inhibitory Concentrations of Antibiotics on Adhesiveness of Escherichia coli in Vitro*

Abstract

The adhesion of radiolabeled Escherichia coli (strain SS142) to monolayers of Intestine 407, a human epithelioid tissue culture cell line, was investigated. In this assay the adhesion of bacteria grown in the presence of subminimal inhibitory concentrations of tetracycline, clindamycin, or trimethoprim-sulfametrole was reduced in a manner that was dose dependent. In contrast, at such concentrations nalidixic acid enhanced the adhesion of this bacterial strain, and other antibiotics—e.g., penicillin G, ampicillin, mecillinam, cephacetrile, cephalexin, cefotaxime, chloramphenicol, and streptomycin—did not affect its adhesiveness.