Mastitis in Cattle: Role of C. perfringens

Bovine mastitis, a leading cause of economic loss in dairy industry, has traditionally been associated with aerobic pathogens; however, emerging evidence implicates anaerobic bacteria such as Clostridium perfringens in intramammary infections. The present study aimed to isolate and identify C. perfringens from milk samples of cows with clinical (n=30) and subclinical (n=30) mastitis, determine toxin profiles using ELISA and PCR genotyping, assess antimicrobial susceptibility, and detect key resistance genes via multiplex PCR. All 30 subclinical samples tested positive by the California Mastitis Test (CMT), confirming 100% mastitis prevalence among screened cows. Overall, C. perfringens was recovered from 53% of clinical and 30% of subclinical samples (41.6% overall), with pathogenic strains present in 30% of clinical and 13.3% of subclinical cases. ELISA revealed that 100% of the 13 isolates produced alpha toxin, while none expressed beta or epsilon toxins, indicating a dominance of toxinotype A in both clinical and subclinical manifestations. Antimicrobial susceptibility testing demonstrated high resistance rates to penicillin (69.2% clinical, 23% subclinical), oxytetracycline (61.5% clinical, 23% subclinical), and chloramphenicol (53.8% clinical, 15.3% subclinical), whereas all isolates remained susceptible to ofloxacin and vancomycin. Multidrug resistance (MDR) was identified in 38.5% of isolates (3 of 6 clinical; 2 of 3 subclinical). Multiplex PCR confirmed that all isolates harboredcpa (alpha toxin). The cpe (enterotoxin) gene was detected in 2 of 5 tested isolates; tetK (tetracycline resistance) was present in 4 of 5; bla (β-lactamase) in 4 of 5; and ermB (macrolide-lincosamide-streptogramin B resistance) in 4 of 5—results that match the corresponding phenotypic resistance profiles. These findings underscore the emerging role of C. perfringens as a significant mastitis pathogen with notable virulence and resistance determinants, highlighting the need for vigilant anaerobic diagnostics, judicious antibiotic stewardship, and alternative control measures in dairy herds.