The rising threat of vancomycin-resistant Staphylococcus aureus (VRSA) poses serious risks to Egyptian dairy herds, as revealed by recent research examining the prevalence of this and methicillin-resistant Staphylococcus aureus (MRSA) strains associated with bovine mastitis. A study conducted from October 2018 to April 2020 collected 808 milk samples from 202 dairy animals across various farms, discovering alarming rates of antibiotic resistance.
Researchers found a 48.4% incidence of mastitis in buffaloes and 29.2% in cattle among the tested dairy animals. Out of the 65 Staphylococcus species isolates, 27 coagulase-positive Staphylococcus aureus (CoPS) strains were confirmed. Notably, VRSA was detected in 85.2% of CoPS isolates, showing minimal inhibitory concentrations (MIC) ranging between 64 to 1024 µg/mL. This extensive resistance to vancomycin indicates the detrimental impact these pathogens can have on bovine health, public safety, and dairy production.
All CoPS isolates exhibited resistance to multiple antibiotics and harbored the mecA gene, which is responsible for methicillin resistance. The study also identified different resistance patterns, with some strains classified as pandrug-resistant (PDR) or extensively drug-resistant (XDR), raising concerns for the treatment of infections.
“The ability of MRSA and VRSA isolates to form biofilms, alongside their resistance profiles, highlights the significant risk they pose to both animal welfare and public health,” said the authors of the article. The biofilm formation capability (a mechanism used by bacteria for survival and persistence) was present across all tested isolates. Strong and moderate biofilm producers were identified, indicating the potential for these bacteria to survive treatments intended to eliminate them.
The presence of virulence factors, including enterotoxin genes and toxic shock syndrome toxin genes, suggests these strains not only contribute to mastitis but also have the potential to cause serious diseases for consumers through contaminated milk. The study found various virulence traits distributed among the isolated strains, with strong correlations noted between antimicrobial resistance and the ability to produce biofilms.
This study also emphasizes the need for stringent hygiene practices and surveillance strategies to mitigate the risks posed by these formidable pathogens. The findings advocate for higher standards of care and oversight within dairy farming to curb the spread of resistant infections.
Importantly, the researchers concluded, “The emergence of MRSA and VRSA complicates the treatment of bovine mastitis and poses a threat to public health. Immediate action is necessary to prevent the escalation of this situation.” The insights gained from this research serve as a call to action for policymakers, dairy farmers, and veterinarians to work collectively to implement effective control measures.
