Correlation Between in vitro Biofilm Formation and Virulence Properties of Extra-Intestinal Pathogenic Escherichia Coli (Expec)

Abstract

About 65 Escherichia coli strains isolated from extra-intestinal sites were included in this study to determine their biofilm formation capability and virulence properties. About 87% ExPEC isolates were motile and 12.3% were found to be non-motile. Only 12.30% isolates were strong biofilm former (SBF >1.5) whereas 18.46% isolates were non biofilm former. About 71% isolates were capable to express curli but curli expression is lower in isolates from pus and peritoneal fluid. About 41.53% isolates have moderate capability (CSH value 21-50%) to adhere to hydrocarbons whereas 20% didn’t show any hydrocarbon adherence capability. Most of the isolates showed moderate cell aggregation (60-80%) potential with S. maltophila but 15.4% isolates were found to be non-aggregative. Forty-one (63.07%) strains were resistant to 2 or more of the most commonly clinically used antibiotics. 44.6% isolates were haemolytic, 35.3% showed colicin activity, 47.7% were MRHA positive, 49.2% had SAT value ≤2.0 M and 9.2% were protease producer. About 77% (50 out of 65) of the isolates harbor type 1 gene. csgA gene was found in 61.5% (40) isolate, papC was found in 64.6% (42), afa and sfa genes were found in 67.7% (44) each. Biofilm formation may contribute to the pathogenic potential of ExPEC.