Carriage of Methicillin-Resistant Staphylococci and Their SCC mec Types in a Long-Term-Care Facility

Abstract

Coagulase-negative staphylococci (CNS) belong to the normal microbial flora of the skin and mucous membranes of humans. The most frequently encountered CNS species in humans, in decreasing order of occurrence, are Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus saprophyticus, and Staphylococcus lugdunensis (8). CNS are an important cause of nosocomial infections, particularly causing foreign device-related infections and infections among immunocompromised patients. In a recent prospective laboratorybased surveillance in four Finnish acute-care hospitals, 76% of the blood culture CNS isolates were resistant to methicillin (meticillin) (23

Evolution of Nasal Carriage of Methicillin-Resistant Coagulase-Negative Staphylococci in a Remote Population

“…Rates similar to ours have been reported only in inpatients, notably those hospitalized in long-term-care facilities (20,25). Promiscuity and suboptimal hygienic conditions in this traditional population may contribute to this finding.…”

“…Indeed, similar SCCmec patterns were observed in MRSA and MR-CoNS isolates from the same health care environment (2,13,20,48,51). Moreover, SCCmec IVa sequences from MRSE display Ͼ98% identity with those carried by MRSA (3,49), including when CA-MRSE and CA-MRSA strains were compared, suggesting that SCCmec transfer can occur in the community (1).…”

Detection of Methicillin-Resistant Staphylococcus aureus by a Duplex Droplet Digital PCR Assay

“…While these two discordant isolates might represent misidentifications by microbiologic techniques, it is possible that they might have lost the mecA gene during prolonged storage, as has been reported previously (19). The presence of mecA has been reported in several coagulasenegative staphylococcal (CoNS) species, including S. epidermidis (20,21), Staphylococcus haemolyticus, and Staphylococcus simulans (22). For this reason, specificity was further examined by testing of MSSA strains, as well as both methicillin-susceptible and methicillin-resistant CoNS strains.…”

Molecular diagnostics and genotyping of MRSA: an update

“…However, sensitivity and specificity of these assays may be compromised owing to the presence of methicillin-resistant coagulase-negative staphylococci (MRCoNS), variability within the used S. aureusspecific genes or variability within the SCCmec cassette. This may lead to false-negative (e.g., gene mutation or SCCmec variants) or false-positive results (e.g., deletion of the mecA gene from the SCCmec region) [29][30][31][32].…”