Rapid increase of genetically diverse methicillin-resistant Staphylococcus aureus, Copenhagen, Denmark

• Published in: Emerging infectious diseases Vol. 13; no. 10; pp. 1533 - 1540
• Main Authors: BARTELS, M.D, BOYE, K, RHOD LARSEN, A, SKOV, R, WESTH, H
• Format: Journal Article
• Language: English
• Published: United States U.S. National Center for Infectious Diseases 01-10-2007; Centers for Disease Control and Prevention
• Subjects: Biological and medical sciences; Communicable Diseases, Emerging - genetics; Communicable Diseases, Emerging - microbiology; Community-Acquired Infections - epidemiology; Community-Acquired Infections - genetics; Community-onset MRSA; Cross Infection - genetics; Denmark - epidemiology; Evolution, Molecular; Genetic aspects; Genetic Variation - drug effects; Genetic Variation - genetics; Humans; Identification and classification; Medical sciences; Methicillin Resistance - genetics; Miscellaneous; MLST; MRSA; Panton-Valentine leukocidin; Phylogeny; Public health. Hygiene; Public health. Hygiene-occupational medicine; spa typing; Staphylococcal Infections - drug therapy; Staphylococcal Infections - epidemiology; Staphylococcal Infections - genetics; Staphylococcus aureus; Staphylococcus aureus - classification; Staphylococcus aureus - drug effects; Staphylococcus aureus - genetics; Staphylococcus aureus infections; Denmark; Nosocomial infection; Skin; Hospital; Epidemiology; Bibliography; Hygiene
• ISSN: 1080-6040; 1080-6059
• DOI: 10.3201/eid1310.070503

In Copenhagen, methicillin-resistant Staphylococcus aureus (MRSA) accounted for <15 isolates per year during 1980-2002. However, since 2003 an epidemic increase has been observed, with 33 MRSA cases in 2003 and 110 in 2004. We analyzed these 143 cases epidemiologically and characterized isolates by pulsed-field gel electrophoresis, Staphylococcus protein A (spa) typing, multilocus sequence typing, staphylococcal chromosome cassette (SCC) mec typing, and detection of Panton-Valentine leukocidin (PVL) genes. Seventy-one percent of cases were community-onset MRSA (CO-MRSA); of these, 36% had no identified risk factors. We identified 29 spa types (t) and 16 sequence types (STs) belonging to 8 clonal complexes and 3 ST singletons. The most common clonal types were t024/ST8-IV, t019/ST30-IV, t044/ST80-IV, and t008/ST8-IV (USA300). A total of 86% of isolates harbored SCCmec IV, and 44% had PVL. Skin and soft tissue infections dominated. CO-MRSA with diverse genetic backgrounds is rapidly emerging in a low MRSA prevalence area.