title: Distribution of methicillin-resistant Staphylococcus aureus in a low-prevalence area.
abstract: Investigating circulating methicillin-resistant Staphylococcus aureus (MRSA) strains and identifying their accumulations in society are important in the search for strategies for eradicating the pathogen. The aim of this study was to describe the distribution of MRSA in a low-prevalence area where MRSA could be establishing endemicity. MRSA isolates from 802 patients (803 isolates) were included and placed into a timeline (1991-2006) under different categories: hospital (n=270), long-term care facility (LTCF) (n=175) and general practitioner (GP) (n=358). MRSA isolates had been characterized using multilocus sequence-typing, staphylococcal cassette chromosome mec-typing and detection of Panton-Valentine leukocidin-encoding genes (lukS/F-PVL), and were placed in exotoxin-encoding gene clusters. The GP category increased mainly in a cluster with few exotoxin-encoding genes (r=0.760), the LTCF (r=0.804) and the hospital category (r=0.876) mainly in clusters with more exotoxin-encoding genes. ST8-IV, lukS/F-PVL present, increased in the community (1-41 isolates) in the time period 2002-2006, later in the hospital (1-8 isolates, 2004-2006), and finally reached the LTCF (1 isolate, 2006). ST8-IV, lukS/F-PVL absent, could have attained endemicity in LTCFs, where 51 isolates were isolated in 2006. ST125-IV, lukS/F-PVL absent, showing epidemic qualities abroad, caused outbreaks at five LTCFs.
authors.affiliation: Research Centre, Institute of Clinical Epidemiology and Molecular Biology, Akershus University Hospital, Lørenskog, Norway. aina.fossum@medisin.uio.no <aina.fossum@medisin.uio.no>
authors.forename: Aina Elisabeth Fossum
authors.initials: AE
authors.lastname: Moen
authors.forename: Dag Gundersen
authors.initials: DG
authors.lastname: Storla
authors.forename: Geir
authors.initials: G
authors.lastname: Bukholm
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001427:Bacterial Toxins / Q000145:classification / Q000235:genetics; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D005098:Exotoxins / Q000145:classification / Q000235:genetics; D005194:Family Practice / Q000706:statistics & numerical data; D006761:Hospitals / Q000706:statistics & numerical data; D006801:Humans; D008134:Long-Term Care / Q000706:statistics & numerical data*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000187:drug effects / Q000235:genetics; D015995:Prevalence; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D005098:Exotoxins