MICROSCOPIC STUDY OF THE EFFECTS OF SUB-INHIBITORY CONCENTRATIONS OF GENTAMICIN ON CAPSULE PRODUCTION OF PSEUDOMONAS AERUGINOSA

Background-The mucoid strains of Pseudomonas aeruginosa produce a hyperviscous capsule, which has several roles in pathogenesis. In this study, the in vitro microscopic effects of sub-inhibitory concentrations of gentamicin on capsule production by mucoid Pseudomonas aeruginosa were investigated. Methods-The production of a capsule by the mucoid Pseudomonas aeruginosa cells cultured on agar media in the presence of sub-inhibitory concentrations of gentamicin was observed by light and electron microscopy. Results- Capsule production was reduced by 0.5 and 0.25 minimum inhibitory concentrations. The results showed a reduction in capsular size in the presence of subinhibitory concentrations of gentamicin. The size of the capsule in the presence of 0.5 MIC gentamicin was less than its size in 0.25 MIC gentamicin. Conclusion-The results confirm that the production of alginate was reduced and consequently, P. aeruginosa infections might be prevented by sub-inhibitory concentrations of gentamicin.