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 sub-inhibitory 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.