European Journal of Biomedical and Pharmaceutical Sciences

PHENOTYPIC EVALUATION OF BIOFILM FORMATION IN HUMAN PATHOGENIC BACTERIAL ISOLATES FROM DIFFERENT CLINICAL SPECIMENS

Rajalakshmi Ramachandran* and Sangeetha D.

ABSTRACT

The purpose of this study was to evaluate three methods for detection of biofilm formation of gram negative and gram positive human pathogenic bacterial isolates from different clinical specimens. For detection of biofilm formation, 150 clinical strains were screened by Microtiter plate (MTP), Tube method (TM) and Congo red agar (CRA) method. Of the 150 clinical strains 112 (74.7 %) exhibited a biofilm-positive phenotype following 48 h under the optimized conditions in the MTP method and strains were further classified as strong 74 (49.3 %), moderate 24 (16.0 %) while in 14 (9.3 %) as weak and 38 (25.3 %) strains were no biofilm was detected. Though TM correlated well with the MTP test for 102 (68.0 %) biofilm producers, in which same strains showed as strongly biofilm producing strains as MTP method, weak producers were difficult to categorize from biofilm negative isolates. Screening on CRA does not correlate well with either of the two methods for detecting biofilm formation. The MTP method was found to be most sensitive, accurate and reproducible screening method for detection of biofilm formation in gram negative and gram positive organisms.

Keywords: Biofilm, pathogens, adherence, microtiter plate, congo red agar.