Methicillin-resistant Staphylococcus aureus containing mecC in Swedish dairy cows

Area of Science:

• Veterinary Microbiology
• Antimicrobial Resistance
• Food Safety

Background:

• Previously, methicillin-resistant Staphylococcus aureus (MRSA) was not identified in Swedish cattle populations.
• The emergence of the novel mecC gene, a homologue to mecA, prompted a re-evaluation of existing Staphylococcus aureus isolates.

Purpose of the Study:

• To investigate the presence of the mecC gene in bovine Staphylococcus aureus isolates from Sweden.
• To determine if MRSA has emerged in Swedish cattle, particularly those with reduced susceptibility to beta-lactams.

Main Methods:

• Retrospective analysis of bovine Staphylococcus aureus isolates.
• Testing for the presence of the mecC gene in isolates exhibiting elevated minimum inhibitory concentrations (MICs) of beta-lactams.

Main Results:

• The mecC gene was successfully detected in four of the tested bovine Staphylococcus aureus isolates.
• This marks the first identification of MRSA in Swedish cattle, specifically strains carrying the mecC gene.

Conclusions:

• The study confirms the presence of MRSA, defined by the mecC gene, in Swedish cattle, representing a novel finding of domestic animal origin.
• The findings underscore the potential for animal populations to act as reservoirs for MRSA, posing a risk for human transmission.
• Current occurrence of MRSA among Swedish cattle appears to be limited.