Biofilm production, antibiotic resistance and the presence of ica, bap, agr and blaz genes in bovine mastitis-associated Staphylococcus aureus isolates from Karnataka. Indian Journal of Comparative Microbiology, Immunology and Infectious Diseases

Abstract

Biofilm formation is an important virulence determinant of Staphylococcus aureus which is a major etiological agent of bovine mastitis. Here, 132 bovine mastitis-associated S. aureus were subjected to biofilm production, antimicrobial susceptibility, and the detection of ica, bap, agr and blaZ genes. It was found that 33.3% of the isolates produced biofilm. The number of isolates resistant to individual antibiotics increased by 1.2- to 7.0-fold when growing in biofilm versus planktonic mode of growth, and the spectrum of antibiotics as well as the number of isolates resistant to various antibiotics increased with the increase in the density of the biofilm. However, there was no correlation between the strength of biofilm and the extent of antibiotic resistance. When evaluated for the presence of genes reported to be associated with biofilm formation, bap gene was detected in a significant number (12.9%) of the isolates.