title: Methicillin resistance in Staphylococcus isolates: the "mec alphabet" with specific consideration of mecC, a mec homolog associated with zoonotic S. aureus lineages.
abstract: Livestock-associated (LA) methicillin-resistant Staphylococcus aureus (MRSA) have globally emerged during the past decade. In Europe, this was particularly due to the occurrence of LA-MRSA strains associated with the clonal complex (CC) 398 as defined by multilocus sequence typing. However, more recently animal-adapted clonal lineages of S. aureus showing phenotypic methicillin resistance have been identified such as CC130, CC599, CC59, CC1943 and CC425. These newly emerging LA-MRSA CCs/STs caused infections in animals and zoonoses in humans. In contrast to other S. aureus clonal lineages, the methicillin resistance of the latter CCs/STs is based on a mecA gene homolog, designated mecC, which is part of a distinct SCCmec type (SCCmec XI). Including mecB found in Macrococcus caseolyticus, henceforth, the "mec alphabet" comprises three major gene types with several allotypes. As known for mecA, the gene homolog mecC is also not restricted to S. aureus, but found in several staphylococcal species including S. sciuri, S. stepanovicii and S. xylosus (mecC1 allotype). First investigations showed a wide geographical distribution of mecC-MRSA in Europe and a broad diversity of host species including livestock, companion and wildlife animals. In particular, wild rodents and insectivores might serve as reservoir for staphylococci harboring mecC. Economic burden may be caused by mastitis of dairy cattle. Livestock animals may likely serve as source for human infections with mecC-MRSA; reported cases comprise skin and soft tissue infections, osteomyelitis and bacteremia. Due to the divergent molecular nature of mecC-MRSA, its diagnostics is hampered by difficulties to verify the methicillin resistance using phenotypic as well as DNA-based procedures, which could have negative consequences for therapy of mecC-MRSA-caused infections.
authors.affiliation: Institute of Medical Microbiology, University Hospital Münster, D-48149 Münster, Germany. Electronic address: kbecker@uni-muenster.de.
authors.forename: Karsten
authors.initials: K
authors.lastname: Becker
authors.affiliation: Institute of Medical Microbiology, University Hospital Münster, D-48149 Münster, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Ballhausen
authors.affiliation: Institute of Hygiene, University Hospital Münster, D-48149 Münster, Germany.
authors.forename: Robin
authors.initials: R
authors.lastname: Köck
authors.affiliation: Institute of Medical Microbiology, University Hospital Münster, D-48149 Münster, Germany.
authors.forename: André
authors.initials: A
authors.lastname: Kriegeskorte
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D002417:Cattle; D004197:Disease Reservoirs; D005060:Europe / Q000453:epidemiology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D016106:Methicillin Resistance; D017720:Molecular Epidemiology; D012377:Rodentia; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D015047:Zoonoses / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission
chemical_list: D001426:Bacterial Proteins
keywords: Companion animal; Diagnostics; Livestock; Methicillin-resistant Staphylococcus aureus; Wildlife animal; Zoonosis; mecC