Effects of antibiotics on adherence of Pseudomonas aeruginosa and Pseudomonas fluorescens to A549 pneumocyte cells

The aim of this study was to evaluate the effect of antibiotics at subminimal inhibitor/concentrations (sub-MIC) on fluorescent pseudomonas adherence to A549 pneumocyte cells. Pseudomonas fluorescens MFO isolated from contaminated raw milk and Pseudomonas aeruginosa NK125502 isolated from a cystic fibrosis patient's lung adhered to A549 cells. As previously shown for P. aeruginosa, P. fluorescens bound to A549 cells in a dose-dependent manner over a wide range of bacterial concentrations. Bacterial growth in the presence of polymyxin B or gentamicin at MIC/2 had no effect on the adherence of NK125502 and MFO to A549 cells. Instead, MIC/2 and MIC/8 of cefsulodin or chloramphenicol decreased the adherence of the two strains. A decrease in MFO adherence was also observed with cefsulodin at MIC/32. We conclude that, in addition to their antibacterial activity, cefsulodin and chloramphenicol could be effective in preventing Pseudomonas adherence to respiratory epithelium. Copyright (C) 2000 S. Karger AG, Basel.