Characterization of methicillin-resistant Staphylococcus aureus from healthy carrier chickens

Area of Science:

• Veterinary Microbiology
• Food Safety
• Antimicrobial Resistance

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in human medicine, increasingly recognized in veterinary contexts.
• Limited epidemiological data exists on MRSA in broiler and layer chickens, despite its detection in various livestock.
• Understanding MRSA prevalence and types in poultry is crucial for One Health approaches.

Purpose of the Study:

• To investigate the epidemiology of MRSA in Belgian poultry farms.
• To compare the efficacy of single versus double enrichment broth methods for MRSA isolation.
• To characterize isolated MRSA strains regarding antimicrobial resistance and genetic profiles.

Main Methods:

• Survey of 372 poultry farms in Belgium.
• Comparison of two MRSA isolation methods: European Food Safety Authority (EFSA)-recommended double enrichment vs. single enrichment.
• Characterization of MRSA isolates using antimicrobial resistance profiling, spa typing, multi-locus sequence typing (MLST), and SCCmec typing.

Main Results:

• MRSA prevalence was 0.8% with double enrichment and 1.8% with single enrichment, indicating higher sensitivity for the latter.
• Identified MRSA strains included livestock-associated (LA) MRSA ST398 and hospital-acquired (HA) MRSA ST239.
• All isolates were resistant to erythromycin and tetracycline, but susceptible to linezolid, mupirocin, and vancomycin.

Conclusions:

• A single enrichment broth method offers higher sensitivity for isolating LA-MRSA from poultry.
• Both typical LA-MRSA ST398 and human-associated MRSA strains are present in Belgian poultry.
• Findings highlight the need for continued surveillance of MRSA in food-producing animals.