In vitro and in vivo evaluation of some antimicrobials and disinfectants against bacterial pathogens from hoof lesions in dairy cattle

Lameness in dairy cattle is prevalent worldwide and has serious economic and welfare implications. Nevertheless, it is an overlooked and least studied dairy problem in Pakistan.

This study was executed for in vivo and in vitro evaluation of antimicrobials and disinfectants against bacterial pathogens from hoof lesions of commercial dairy cattle.

For in vitro studies, 23 bacterial isolates (n=10 Staphylococcus aureus, n=8 Fusobacterium necrophorum, and n=5 Bacteroides) from hoof lesions were used for antimicrobial and disinfectants susceptibility testing. In vivo trials were carried out among 4 groups of dairy cows suffering from hoof lesions using different combinations of antimicrobials, non-steroidal anti-inflammatory drugs (NSAIDs), and disinfectants either parenterally or topically.

Results indicated that most of the isolates of S. aureus, F. necrophorum, and Bacteroides were resistant to penicillin, amoxicillin, trimethoprim + sulphamethoxazole, oxytetracycline, and tylosin. Ciprofloxacin and gentamicin were the most effective antimicrobials (in vitro) against all three bacterial pathogens. Comparison of in vitro efficacy of disinfectants showed that copper sulfate was the most effective disinfectant against the three pathogens followed by povidone-iodine and chloroxylenol. In vivo trials revealed that ciprofloxacin at 5 mg/kg/day intramuscular (IM) for 7 days, flunixin meglumine at 2.2 mg/kg/day IM for 7 days, and copper sulfate (5% solution) as foot-bath twice daily for 21 days was the most effective treatment regimen to treat lameness in commercial dairy cows.

It was concluded that in vitro antibiogram and disinfectant studies were useful tools to assess the effectiveness of routinely used antimicrobials and disinfectants for the treatment of lameness.