mecCcarrying

MecC-carrying refers to Staphylococcus aureus and related staphylococci that harbor the mecC gene, a mecA homolog, within the SCCmec genetic element. The mecC gene encodes an altered penicillin-binding protein, PBP2c, which reduces affinity for beta-lactam antibiotics and confers methicillin resistance.

MecC is located on a distinct SCCmec element, designated SCCmec XI, and is commonly associated with livestock-adapted strains. MecC-carrying MRSA has been isolated from cattle, other livestock, and from humans with animal contact, indicating a zoonotic reservoir and potential animal-to-human transmission.

Standard phenotypic tests and many mecA-targeted diagnostics may fail to detect mecC-mediated resistance, leading to underdiagnosis. Molecular assays specific for mecC or broad-spectrum PCR are used to identify these strains; some PBP2a-based assays may not reliably detect PBP2c.

Clinically, mecC-carrying MRSA is resistant to beta-lactams but often remains susceptible to non-beta-lactam antibiotics; treatment should be guided by susceptibility testing. Infection control and surveillance programs include mecC as part of MRSA characterization.

Global reports show mecC-carrying MRSA is present in several regions but remains less common than mecA MRSA. Ongoing surveillance and research aim to clarify transmission dynamics, reservoir species, and optimal diagnostic strategies.