A methicillin-resistant Staphylococcus aureus (MRSA) Sequence Type 8, spa type t11469 causing infection and colonizing horses in Italy.

This research highlights the detection of a specific type of Methicillin-resistant Staphylococcus aureus (MRSA) causing infections in horses in Italy. The study also emphasizes the significant role improper antibiotic usage and hospitalization play in increasing susceptibility to MRSA infection, and how the environment is a critical source of exposure.

Isolation of MRSA Strain

• Researchers discovered a specific strain of Methicillin-resistant Staphylococcus aureus (MRSA) from a sick mare with chronic purulent sinusitis in Italy.
• This mare had undergone sinus surgery three months before the discovery.

MRSA Detection in other Sources

• Environmental samples and samples from humans, horses, and dogs were collected from the mare’s stable and the Veterinary Hospital where the mare had been treated.
• MRSA was detected from some of these samples, particularly other horses at both the stable and hospital, as well as from the environment in both locations.

Analysis of the MRSA strain

• All the isolated MRSA strains were found to belong to the CC8, ST8-t11469-SCCmec-IVa group.
• These strains exhibited similar phenotypic and genetic multidrug resistance patterns and macrorestriction-pulsed-field gel electrophoresis profiles.

Infection in Humans

• The only MRSA strain detected in humans during this study was a variant of the CC1, ST1-t127-SCCmec-IVa.
• This indicates that while humans were exposed to the same environment, they did not contract the exact same strain of MRSA that affected the horses.

MRSA Infection in Horses in Italy

• This is the first reported case of a clinical MRSA infection in a horse in Italy.
• The findings reinforce the belief that the misuse of antibiotics and hospitalization or surgery can create risk factors for MRSA colonization or infection in horses.
• The study also points out the environment as an essential source for exposure to this bacteria.