MODIFIED CONGO RED AGAR METHOD TO DETECT BIOFILM PRODUCTION BY ENTEROCOCCUS FAECIUM

Background and Aim:Enterococcus faecium in Hospitalized patients can cause urinary tract infection related to the use of catheter due to biofilm production. There are various phenotypic methods to detect biofilm formation. One method is based on culture in brain heart infusion agar (BHIA) including Congo red and sucrose. The aim of the present study was to determine the biofilm formation ability of vancomycin-resistant E. faecium isolates using Modified Congo red agar(MCRA).Methods:A total of 29 isolates of E. faecium were collected from hospitalized patients at Ahvaz educational hospitals. Biochemical and molecular techniques were used to identify vancomycin- resistant E. faecium strains. We have confirmed MCRA capacity to detect biofilm production in 29 E. faecium strains, including 100% vanA gene–positive strains.Results:All 29 isolates were resistant to vancomycin and 75.7% of them were also biofilm producers. The rate of isolates with Very black, Black, Almost black and Red biofilm formation were 27.5%, 31%, 17.2% and 24.3%, respectively.Conclusion:As shown in the results, there is an association between vancomycin resistance E. faecium isolates and biofilm formation The MCRA method is fast, reproducible, and presents advantage to determine differences colonies in biofilm production between E. faecium strains. Also the MCRA method is a confident tool and can help to determine the real contribution of E. faecium in the biofilm formation process.

Keywords:

Congo red agar , Biofilms , Vancomycin-resistant Enterococcus faecium