Effect of subMIC of gentamicin on biofilm formation, peptides profiling, and expression of colonization and spreding genes of Enterococcus faecalis

Abstract

In this study, we aimed to evaluate comprehensively the changes in E.faecalis when exposed to sub-MIC of the gentamicin, including changes in virulence factors such as genes involved in bacterial colonization and spreading, changes in biofilms, and changes in structural and functional peptides.

Materials and Methods: One standard strain of mmh596 and 25 clinical isolates of E.faecalis from patient specimens were cultured in two media including gentamicin-free media and another with a sub-MIC of gentamicin. The biofilm formation was performed using microtiter plate method. The study of colonization and spreading genes were performed using Real Time PCR and the study of bacterial peptide changes after exposure to antibiotic was performed by MALDI-TOF MS method.

Results: Gentamicin significantly increased biofilm formation in 62% of the isolates and little changes were observed in the other isolates. The amount of proteins effective in biofilm formation and the proteins that provide the living conditions of the bacteria in stressful situations were increased and the proteins related to cell division and metabolism were decreased. Gentamicin also increased the expression of the efaA and esp genes and decreased the expression of the asa and cylA genes and no significant changes were observed in the expression of the gelE and ebp genes.