The effect of sublethal concentrations of aminogycosides on adherence of Pseudomonas aeruginosa to hamster tracheal epithelium

Perfused hamster tracheal explants were used to examine the adherence of mucoid and non-mucoid strains of Pseudomonas aeruginosa to intact tracheal epithelium when grown in 0.5 MIC of tobramycin or gentamicin. Tracheal explants were perfused for 2 h with 10(7) cfu of P. aeruginosa grown overnight in trypticase soy broth containing 0.5 MIC of tobramycin or gentamicin or without antibiotics. After infection, the explants were washed and a 4 mm section was homogenized, diluted and plated for colony counts. Mucoid strains of P. aeruginosa grown in the presence of the aminoglycosides did not produce alginate and were not as adherent as the same strains which were not grown in antibiotics. Adherence of non-mucoid strains of P. aeruginosa grown in sublethal concentrations of the aminoglycosides was not significantly reduced compared with the adherence of the same strains which were not exposed to antibiotics. These results indicate that mucoid strains of P. aeruginosa growing in the presence of sublethal concentrations of aminoglycosides do not produce alginate and may not colonize the epithelial surface.