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

Emerg Infect Dis. 2007 Oct;13(10):1533-40. doi: 10.3201/eid1310.070503.

Abstract

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.

MeSH terms

  • Communicable Diseases, Emerging / genetics
  • Communicable Diseases, Emerging / microbiology
  • Community-Acquired Infections / epidemiology
  • Community-Acquired Infections / genetics
  • Cross Infection / genetics
  • Denmark / epidemiology
  • Evolution, Molecular
  • Genetic Variation / drug effects*
  • Genetic Variation / genetics
  • Humans
  • Methicillin Resistance / genetics*
  • Phylogeny
  • Staphylococcal Infections / drug therapy
  • Staphylococcal Infections / epidemiology
  • Staphylococcal Infections / genetics*
  • Staphylococcus aureus / classification
  • Staphylococcus aureus / drug effects
  • Staphylococcus aureus / genetics*