Retrospective study of necropsy-associated coagulase-positive staphylococci in horses.

This research article looks into the role and impact of coagulase-positive staphylococci (CoPS), namely Staphylococcus aureus and Staphylococcus pseudintermedius, in equine deaths over a decade, along with exploring their resistance to antibiotics and the presence of virulence genes.

Overview of the Study

• The research constitutes a retrospective study of necropsies performed on horses over ten years (1995-2006). It examined the role of coagulase-positive staphylococci (CoPS), a type of bacteria, in the morbidity and mortality of horses.
• A total of 3,457 necropsies (post-mortem examinations) were evaluated, to identify the presence and impact of CoPS, which caused illness in 1.7% of cases. These microbes thus had a sizable role in the health issues of the horses evaluated.
• A majority of the CoPS species found were Staphylococcus aureus (59) and one case of Staphylococcus pseudintermedius. These bacteria were linked to the cause of death or euthanasia in 90% of the cases with CoPS (54 out of 60 cases).

Antibiotic Resistance and Virulence Genes

• The study also explored the levels of antibiotic resistance found in these cases, with penicillin G and tetracycline resistance detected in 62.7% and 23.7% of cases respectively. This underscores the growing concern of antibiotic resistance in microbial pathogens and the need for new antibiotics or treatments methodologies.
• Virulence genes were identified in 91.7% of the CoPS strains, with many presenting seh or sei enterotoxin genes. These genes make the bacterial strains more pathogenic, increasing their ability to cause disease.

Identification of Methicillin-Resistant Strains

• Of special note, three isolates of methicillin-resistant Staphylococcus aureus (MRSA), a type of antibiotic-resistant bacteria, were found. These belonged to the t064 spa-type.
• One strain of MRSA was isolated as far back as 2003. This strain is considered particularly significant as it could be one of the earliest cases of equine MRSA in France. The researchers emphasized the importance of vigilance in identifying such antibiotic resistant strains early, due to their potential impact on the health of horses and the implications for the management of infections.