Detection of biofilm formation among the clinical isolates of Enterococci: An evaluation of three different screening methods

Abstract

This study was conducted to evaluate three methods for the detection of biofilm formation in Enterococci. For the detection of biofilm production ,128 clinical isolates of Enterococcus spp were screened by tissue culture plate (TCP), Tube method (TM) and Congo red agar (CRA) method. Of the 128 Enterococcus spp, 71( 55.5%) isolates showed a biofilm positive phenotype under the optimized conditions in the TCP method and strains were further classified as strong 28 (31.9%) ,moderate 22 (17.2%) ,weak 21 (16.5%) wherein 57(44.6 %) isolates no biofilm was detected. Though TM correlated well with the TCP method for 14 (11%) strongly biofilm producing strains, weak producers were difficult to discriminate from biofilm negative isolates We can conclude from our study that the TCP method is a reliable and sensitive screening method for the detection of biofilm formation by Enterococci when compared to TM and CRA methods.TCP methodalso has the advantage of being a quantitative model to study the adherence of Enterococci and can be recommended as a general screening method for detection of biofilm producing Enterococci in laboratories.