DETECTION OF BIOFILM FORMATION AMONG METHICILLIN RESISTANT Staphylococcus aureus FROM SUBCLINICAL BOVINE MASTITIS

Abstract

Mastitis is a condition responsible for causing severe economic losses to dairy industry and a public health threat due to reduced milk production, massive antibiotic usage and deteriorated milk quality. Among the diverse bacterial and physical etiologies of mastitis, Staphylococcus aureus remains the most significant. The primary aim of this study is to detect methicillin-resistant Staphylococcus aureus (MRSA) in mastitic milk samples and to assess their biofilm-forming ability. Total 368 milk samples were collected from buffaloes targeting various locations and screened for subclinical mastitis using California Mastitis Test. The positive samples were subjected to identification and confirmation of Staph aureus using standard microbiological methods and polymerase chain reaction. The Kirby-Bauer method was used to determine the multidrug-resistance profile and methicillin-resistant status of Staphylococcus aureus isolates, followed by confirmation through amplification of the mecA gene. The biofilm forming potential of all isolates was done using Microtiter Plate Method (MTP). The results showed that 42.40% (156/368) of milk samples were positive for subclinical mastitis and among them Staph aureus was detected in 71 isolates. On the basis of Kirby-Bauer test and MecA gene (n=26) isolates were confirmed as MRSA. It was observed that all the MRSA isolates exhibited varying levels of biofilm production, with 65.38%, 26.92%, and 7.69% demonstrating strong, moderate, and weak biofilm formation, respectively while the 82.22% of MSSA isolates showed biofilm production. The findings indicate a notable presence of MRSA in bovine mastitis and biofilm formation is more pronounced in MRSA compared to MSSA isolates. The control of biofilm forming MRSA in mastitis requires strict milking hygiene, early detection of infection, judicious antibiotic use and implementation of herbal preparations targeting biofilm disruption to limit infection spread.