Clinicopathological findings and etiological characterization in caprine gangrenous mastitis

Gangrenous mastitis ranks among the most economically significant diseases affecting small ruminants. In the present study, along with clinicopathological studies, the etiological characterisation and the contribution of various virulence factors of caprine gangrenous mastitis was studied. Staphylococcus aureus with colony count ranging from 10⁶ to 10⁸ CFU/mL has been identified as the etiological agent in 15 gangrenous mastitis affected goats based on cultural isolation, biochemical characteristics and molecular confirmation. Haematological and serum biochemical analysis was carried out in the affected goats which revealed leucocytosis with thrombocytopenia and hypoproteinemia. Phenotypic identification of antibiotic resistance revealed significantly high resistance to enrofloxacin, sulpha-trimethoprim, tetracycline, and gentamicin whereas the antibiotics cefoperazone, ceftriaxone- tazobactam and amoxicillin clavulanate showed least resistance. Toxin genes lukMF, and hla were detected in 66.7 per cent and 60 per cent of the isolates respectively. Antibiotic resistant genes blaZ (13.3 %), tetM (20 %), sul1 (13.3 %), mecA (80 %) and biofilm forming genes like icaA (26.6 %) icaD (40 %) were also detected in the S. aureus isolates. Majority of the isolates revealed significantly higher antibiotic resistance along with toxin genes and all the isolates showed biofilm formation. Biofilm forming ability of S. aureus plays a crucial role in its virulence whereas, antimicrobial resistance has a significant role in potentiating the virulence of pathogen.