Molecular characterization and genotyping of bioflim producing stafylococci associated with bovine mastitis

Abstract

newlineMastitis is an inflammatory disease of dairy animals and is considered as one of the newlinecommonest problems of the dairy industry throughout the world. Though it is a multietiological newlinedisease, Staphylococcus aureus is considered to be a common and potent cause newlineof mastitis due to its wide array of virulence factors and ability of forming biofilm. The newlinepresent study aimed at isolation and identification of biofilm forming S. aureus from newlinemastitic and apparently normal bovine milk samples, and molecular detection of genes newlinerelated to adhesion and biofilm formation, antibiotic resistance and enterotoxin production. newlineThe study also included molecular typing of representative isolates by three methods newlinenamely, multilocus sequence typing (MLST), surface protein A typing (spa typing) and newlineaccessory gene regulator typing (agr typing). The study was further extended to assessment newlineof antibiofilm efficacy of three compounds- chitosan, EDTA and povidone iodine against newlineselected S. aureus isolates in vitro. newlineThe study included a total of 136 milk samples comprising of 26 from mastitic and newline110 from apparently healthy cows. In California Mastitis Test for detection of sub-clinical newlinemastitis, 84 (76.40 %) of the 110 apparently normal milk samples tested positive. On newlinebacteriological examination, 18 (69.23%) of 26 milk samples from mastitic cows and 64 newline(76.19%) of 84 apparently normal milk samples were to be positive for Staphylococcus newlinewith an overall positivity of 74.55%. Altogether 78 (95.12 %) of the 82 Staphylococcus newlineisolates were found to be coagulase positive and confirmed as S. aureus based on detection newlineof the species-specific aroA gene by polymerase chain reaction (PCR). newlineAmong the 78 S. aureus isolates, 54 (69.23 %) were identified as biofilm producers newlinebased on their characteristic growth on Congo red agar (CRA) plates. However, on PCR newlineamplification, 58 (74.36%) of these isolates were found to carry icaA and icaD genes. All newlinethe isolates were found to have both fnbA and clfB genes, while 98.71, 61.50 and 11.53 per newlinecent of th