Prevalence of Methicillin-Resistant Staphylococcus aureus from Equine Nasopharyngeal and Guttural Pouch Wash Samples.

This study investigated the prevalence of Methicillin-resistant Staphylococcus aureus (MRSA) in horse’s nasopharynx and guttural pouch using samples from clinically ill and healthy horses. The research found a low prevalence of MRSA, but pointed out a need for further study on the necessity of sampling multiple anatomic sites for MRSA screening in horses.

Objective and Methods of the Study

• The main goal of the study was to determine how frequently MRSA colonizes the nasopharynx and guttural pouch of horses. This was achieved by examining samples obtained from equine nasopharyngeal wash (NPW) and guttural pouch lavage (GPL) from a field population of horses.
• The study was prospective, compiling a total of 178 samples taken from both clinically ill horses suspected of having Streptococcus equi infection, horses recovering from an S. equi infection, and healthy horses that were being screened for the same infection.
• The samples were processed for Staphylococcus aureus bacteria using aerobic culture methods with mannitol salt broth and two types of selective agar. The researchers also used biochemical methods to identify different Staphylococcus species and pulsed-field gel electrophoresis (PFGE) to determine the genetic relationships between the isolated bacteria.

Results of the Study

• From the 108 horses sampled, 7 yielded methicillin-resistant Staphylococcus (MRS) isolates from the nasopharynx, accounting for a prevalence of 4% among the sampled population.
• Out of these seven horses, three were found to be carrying MRSA while four were carrying methicillin-resistant Staphylococcus pseudintermedius (MRSP).
• The MRSA isolates were all discovered in horses from the same farm, and PFGE revealed them to be USA 500 strains.

Conclusion of the Study

• The researchers concluded that the prevalence rate of MRSA in the community-based horse population is relatively low, congruent with previous studies engaging similar research methods.
• Additionally, the researchers proposed that more comprehensive studies should be performed to understand whether there’s a need for sampling from various anatomical locations when screening horses for MRSA.