SUBCLINICAL MASTITIS - ITS PREVALENCE, RISK ANALYSIS, AND ASSOCIATION WITH METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (MRSA) IN CERTAIN DISTRICTS OF ASSAM, INDIA

• Published in: Exploratory animal and medical research Vol. 14; no. Superbug Spl.; pp. 51 - 62
• Main Authors: Kakati, Suruj Protim, Saikia, Girindra K., Sharma, Rajeev K., Bora, Durlav P., Borah, Probodh, Gogoi, Sophia M., Deka, Pankaj, Konch, Pranab, Konwar, Nayanmoni, Arif, Syed A.
• Format: Journal Article
• Language: English
• Published: West Bengal Veterinary Alumni Association 30.09.2024
• Subjects: assam; bovine; epidemiology; mastitis; meca; mrsa; spa
• ISSN: 2277-470X; 2319-247X
• DOI: 10.52635/eamr/14(S2)51-62

This study investigates the epidemiology of subclinical mastitis, focusing on prevalence, risk factors, bacterial pathogens, virulence factors, antimicrobial sensitivity, and detection of methicillinresistant Staphylococcus aureus (MRSA) bacterial isolates in organized and unorganized dairy farms of Kamrup and adjoining districts of Assam. The overall prevalence of bovine subclinical mastitis was found to be 43.81% using the California Mastitis Test (CMT). Risk factor analysis revealed that age-wise, the highest prevalence was noted in the 4-6 years age group (51.95%) and at 4th lactation (60.40%). Significant associations were found between mastitis prevalence and various factors including age, breed, lactation number, stage of lactation, quarter-wise distribution, farm type, management system, and season. A total of 185 bacterial isolates were obtained, predominantly Staphylococcus spp. (143), with notable occurrences of Streptococcus spp. (22), Escherichia coli (14), and Enterococcus faecalis (6). Staphylococcus aureus emerged as the primary etiological agent, with 81.82% of isolates producing coagulase and 45.45% producing hemolysin, while 54.0% of Staphylococcus aureus isolates tested positive for the protein A (spa) gene. Antimicrobial sensitivity testing revealed enrofloxacin, gentamicin, and ceftriaxone as the most effective antibiotics, with penicillin-G demonstrating the least efficacy. Methicillin resistance was detected in 11.96% of Staphylococcus aureus isolates phenotypically and in 2.56% genotypically (mecA) revealing the emergence of MRSA which is important from a public health point of view. These findings highlight the prevalence of subclinical mastitis, the predominance of Staphylococcus aureus as the causative agent, and the emergence of antimicrobial resistance, which warrants effective control measures and antimicrobial management in dairy farming practices.