New categories designated as healthcare-associated and community-associated methicillin-resistant Staphylococcus...

Area of Science:

• Veterinary Microbiology
• Antimicrobial Resistance
• Canine Infectious Diseases

Background:

• Increasing incidence of Methicillin-Resistant Staphylococcus pseudintermedius (MRSP) in dogs.
• Limited treatment options and understanding of MRSP genotype-phenotype-clinical background relationships.
• Need for improved diagnostics and infection control for canine MRSP.

Purpose of the Study:

• To investigate associations between microbiological and clinical characteristics of MRSP isolates from dogs.
• To differentiate between hospital-acquired MRSP (HA-MRSP) and community-acquired MRSP (CA-MRSP) based on genetic profiles.
• To provide insights for effective treatment and infection control strategies for canine MRSP.

Main Methods:

• Analysis of 282 Staphylococcus pseudintermedius isolates from dogs.
• Genotyping of MRSP strains, focusing on SCCmec types (III and V).
• Correlation analysis between genotypes, clinical data (hospital admission, antimicrobial therapy), and phenotypic properties.

Main Results:

• 195 (69.1%) isolates were mecA-positive MRSP, predominantly SCCmec types III (52.8%) and V (37.4%).
• SCCmec type III MRSP strains showed significant correlation with hospital admission and prior antimicrobial therapy, exhibiting homogeneous genotypes (similar to ST71-MRSP).
• SCCmec type V MRSP strains displayed genotypic and phenotypic heterogeneity, with less correlation to hospital acquisition factors.

Conclusions:

• MRSP strains with SCCmec type III are designated HA-MRSP, while those with SCCmec type V are designated CA-MRSP, analogous to human MRSA.
• Oxacillin Minimum Inhibitory Concentration (MIC) can help discriminate between HA-MRSP and CA-MRSP.
• Distinguishing between HA- and CA-MRSP is crucial for guiding treatment decisions and implementing targeted infection control measures in veterinary settings.