Virulence Characteristics and Biofilm Production in Clinical and Environmental Isolates

Abstract

                         Microbes that grow in a biofilm are associated with chronic and acute human infections that are highly resistant to antimicrobial agents. Soil, water and clinical samples were collected and 62 isolated organisms were screened for biofilm formation and their virulence characteristics were determined. Sixty two isolates were studied for proteinase production, hemolytic activity, DNase production, serum susceptibility and cytotoxic activity. Out of all the isolates grown overnight 22 (35.48%) were able to hydrolyze casein at 37 ° C.  About 26 (41.94%) isolates presented β hemolysis. About 16 (25.81%) isolates showed positive for DNase activity. Cytotoxic activity was presented positive for about 16 (25.81%) isolates and 20 (32.26%) isolates were significantly more resistant to the bactericidal activity of Normal Human Serum. From the total of 62 isolates crystal violet binding assay method detected 45 (72.58%) were biofilm producers. Among 24 pathogenic isolates crystal violet binding assay detected 4 (16.67%) as strong, 13 (54.16%) as moderate and 7 (29.17%) as weak or non- biofilm producers. It was observed higher pathogenicity in biofilm producing bacteria than non- biofilm producers. From the study it was concluded that the majority of the biofilm producers were from clinical isolates.