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

Background and Aim : Enterococcus faecium is a persistence bacterium which its pathogenesisis drastically affected by biofilm formation. Nosocomial infections caused by E. faecium haverapidly increased, and treatment options have become more limited. This is due not only toincreasing resistance to antibiotics but also to biofilm-associated infections. This study evaluatedbiofilm formation in clinical and environmental isolates of multi drug resistance enterococcusfaecium. In biofilm positive E. faecium isolates, the expression antibiotic resistance-related genesin planktonic and biofilm conditions were compared in vitro.Methods : In this study, ۶۹۰ Enterococcus isolates were studied. ۲۲۹ isolates were Enterococcusfaecium. After antibiotic susceptibility testing, ۱۱۳ isolates were resistant to vancomycin. Biofilmformation was investigated in resistant Enterococcus faecium isolates. Six clinical andenvironmental isolates were selected. To determine the enterococcal antibiotic resistance-relatedgenes expression, we used quantitative real-time PCR to compare mRNA levels in Enterococcusfaecium cultures grown in planktonic and biofilm condition to that achieved in laboratory medium.Results : Among ۶۹۰ evaluated strains of Enterococci, among the six genes associated withbiofilm formation, the expression of the pbp۵ gene has the highest expression; Expressionincreased in five isolates and unchanged in only one isolate. Next, the vanA gene increasedexpression in the four isolates and unchanged in tow isolates. The lowest gene expression of thevanB gene increases the expression of only one isolate and unchanged in five isolates. The increaseexpression of ۳ selected resistance genes (vanA, vanB and pbp۵) were confirmed by real-timePCR.Conclusion : The results of the antibiotic resistance and biofilm assay, suggest that there is apersistent and biofilm-producing strains of E. faecium, which could rapidly disseminate in patientsand the environment. Therefore, applications of precautionary and management procedures arehighly required.

کلیدواژه ها:

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