Antibiofilm activity of cell-free supernatants of vaginal isolates of Corynebacterium amycolatum against Pseudomonas aeruginosa and Klebsiella pneumoniae

Biofilm formation is an important factor in the development of antibiotic resistance and chronic infection. In this study, we demonstrated that the cell-free supernatant of vaginal isolates of C. amycolatum caused a reduction in biofilm formation, destroyed the preformed biofilms, altered the cell surface properties and reduced the production of exopolysaccharides in clinical isolates of P. aeruginosa i Kl. pneumoniae. Microscopic observations showed that P. aeruginosa and Kl. pneumoniae biofilm formed small clusters scattered over the surface after treatment with cell-free supernatant of C. amycolatum ICIS 99, in contrast to the dense aggregates observed in controls, as well as the flat, scattered, and unstructured biofilm architecture after treatment of preformed biofilms cell-free supernatant. The cells were flat and relatively unstructured. Based on these results, we hypothesize that C. amycolatum likely produces secondary metabolites with antimicrobial activity and utilizes a similar mechanism of action to bacteriocins and/or biosurfactants. The data obtained open the prospect of studying the metabolic profile of the cell-free supernatant of C. amycolatum to understand the nature and mechanism of the detected antibacterial action and provide further support for the probiotic potential of C. amycolatum vaginal isolates.