title: Molecular epidemiology of methicillin-resistant Staphylococcus aureus in Zurich, Switzerland (2003): prevalence of type IV SCCmec and a new SCCmec element associated with isolates from intravenous drug users.
abstract: The majority of methicillin-resistant Staphylococcus aureus (MRSA) isolates, recovered in 2003 at the Department of Medical Microbiology in Zürich, Switzerland, belonged to major clones that are circulating worldwide. Staphylococcal cassette chromosome mec type IV (SCCmec-IV), harbored by half of the isolates, was found in sequence type 217 (ST 217), which is an allelic variant of epidemic MRSA-15 (designated EMRSA-15), in a new local ST 617 descending from clonal complex CC 8 and in low-level oxacillin-resistant strains of multiple genetic lineages characteristic of community-onset MRSA. SCCmec-I, SCCmec-II, and SCCmec-III were in the minority, and four MRSA isolates had complex, rearranged SCCmec elements. A novel SCCmec-N1 of approximately 30 kb, associated with a dfrA gene and a ccr 4-related recombinase complex, was identified in a large number of low-level oxacillin-resistant isolates, which descended from the successful clonal complex CC 45 and are spreading among intraveneous drug users. In contrast, the SCCmec types of oxacillin-resistant coagulase-negative staphylococci (MRCNS) were of completely different composition. SCCmec type I (SCCmec-I) and SCCmec-II were more frequent than in the MRSA, while fewer contained SCCmec-IV. The other MRCNS displayed 11 different, complex patterns, suggesting frequent recombination between different SCCmec elements. With one ccr-negative exception, these strains amplified between one and three different ccr products, indicating either new varied complexes or multiple ccr loci. This suggests the presence of novel SCCmec types in MRCNS and no extensive interspecies SCCmec transfer between MRSA and MRCNS.
authors.affiliation: Department of Medical Microbiology, University of Zürich, CH-8006 Zürich, Switzerland.
authors.forename: Wei
authors.initials: W
authors.lastname: Qi
authors.forename: Miriam
authors.initials: M
authors.lastname: Ender
authors.forename: Frances
authors.initials: F
authors.lastname: O'Brien
authors.forename: Alexander
authors.initials: A
authors.lastname: Imhof
authors.forename: Christian
authors.initials: C
authors.lastname: Ruef
authors.forename: Nadine
authors.initials: N
authors.lastname: McCallum
authors.forename: Brigitte
authors.initials: B
authors.lastname: Berger-Bächi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D003030:Coagulase / Q000378:metabolism; D006801:Humans; D016106:Methicillin Resistance / Q000235:genetics; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D010068:Oxacillin / Q000494:pharmacology; D015995:Prevalence; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D015819:Substance Abuse, Intravenous / Q000150:complications*; D013557:Switzerland / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D003030:Coagulase; D010068:Oxacillin