Comparison of the expression of Enterococcus faecium biofilm-related genes in biofilm and planktonic conditions

Background and Aim : Enterococcus faecium is a persistence bacterium which its pathogenesis is drastically affected by biofilm formation. Nosocomial infections caused by E. faecium have rapidly increased, and treatment options have become more limited. This is due not only to increasing resistance to antibiotics but also to biofilm-associated infections. This study evaluated biofilm formation in clinical and environmental isolates of multi drug resistance enterococcus faecium. In biofilm positive E. faecium isolates, the expression biofilm-related genes in planktonic and biofilm conditions were compared in vitro.Methods : In this study, ۶۹۰ Enterococcus isolates were studied. ۲۲۹ isolates were Enterococcus faecium. After antibiotic susceptibility testing, ۱۱۳ isolates were resistant to vancomycin. Biofilm formation was investigated in resistant Enterococcus faecium isolates. Six clinical and environmental isolates were selected. To determine the enterococcal virulence-associated gene expression, we used quantitative real-time PCR to compare mRNA levels in Enterococcus faecium cultures grown in planktonic and biofilm condition to that achieved in laboratory medium.Results : Among ۶۹۰ evaluated strains of Enterococci, and among the six genes associated with biofilm formation, the expression of the efaA gene has the highest expression. Expression increased in five isolates and decreased in only one isolate. The four genes fsr, asa, esp and gelE increased in expression in the four isolates. The lowest gene expression of the hyl gene increases the expression of only one isolate. The increase expression of ۵ selected virulence genes (asa۱, fsr, gelE, efaA and esp) were confirmed by real-time PCR.Conclusion : The results of the antibiotic resistance and biofilm assay suggest that there is a persistent and biofilm-producing strains of E. faecium, which could rapidly disseminate in patients and the environment. Therefore, applications of precautionary and management procedures are highly required. Keywords: Enterococcus faecium, biofilm, Gene expression, real-time PCR

کلیدواژه ها:

Enterococcus faecium ، biofilm ، Gene expression ، real-time PCR