Methicillin-resistant coagulase-negative staphylococci isolated from healthy horses in Japan.

The study investigates the prevalence and types of methicillin-resistant bacteria, specifically coagulase-negative staphylococci, in healthy horses in Japan. It found that such resistant strains that could potentially threaten the health of horses and their caregivers are present in the equine population.

Research Methodology

• The study was carried out on 44 horses from 8 different riding clubs in Japan.
• Methicillin-resistant staphylococci were isolated from the skin or nares (the nasal passage) of these horses using a specific medium containing the antibiotic ceftizoxime, which is a beta-lactam antibiotic.
• Pulsed-field gel electrophoresis, a laboratory technique used for the separation and identification of large DNA molecules, was used to determine the clonality or genetic similarity of the isolated bacteria.
• Specific genes linked with antibiotic resistance (mecA, mecl, and mecR1) in the bacteria were identified using polymerase chain reaction (PCR), a common method to amplify and detect DNA sequences.

Research Findings

• Out of the 44 horses sampled, 13 horses (or 29.5% of the total) yielded 15 isolates of methicillin-resistant staphylococci.
• The bacteria isolated belonged to six species (Staphylococcus epidermidis, S lentus, S saprophyticus, S xylosus, S sciuri, and S haemolyticus). Interestingly, methicillin-resistant S aureus, a common and often problematic human pathogen, was seldom isolated.
• Each of the bacterial isolates contained the resistance gene mecA and demonstrated high resistance to beta-lactam antibiotics.
• Additional resistance to other antibiotics such as erythromycin and kanamycin was observed in some isolates.

Conclusion

• The study concludes that methicillin-resistant coagulase-negative staphylococci, highly resistant to various antibiotics, are present in apparently healthy horses in Japan.
• This finding suggests these organisms could pose a potential health risk to horses and those who care for them, including veterinarians, and underline the need for careful healthcare practices and possible additional control measures.