The first sequence Type 80 community-associated methicillin-resistant Staphylococcus aureus strain in the USA

  • Neeltje Carpaij, Department of Medical Microbiology, University Medical Center Utrecht, The Netherlands, The Netherlands
  • Rob Willems, Department of Medical Microbiology, University Medical Center Utrecht, The Netherlands, The Netherlands
  • Jodi Lindsay, Department of Cellular and Molecular Medicine, St. George’s, Univerisity of London, United Kingdom, United Kingdom
  • Marc Bonten, Department of Medical Microbiology, University Medical Center Utrecht, The Netherlands, The Netherlands
  • Ad Fluit, Department of Medical Microbiology, University Medical Center Utrecht, The Netherlands, The Netherlands

    • Objective
    In the last decade methicillin-resistant Staphylococcus aureus (MRSA) is increasingly found in non-hospitalized persons in the community. The genetic background of CA-MRSA is diverse, although on every continent particular clones dominate. These dominant CA-MRSA strains cluster in just 6 lineages: ST1/MW2, the US Midwest clone; ST8/USA300, the epidemic American clone; ST30/USA1100, the Southwest Pacific Oceania clone; ST93, the Queensland clone; ST59, the Asian clone and ST80, the European clone. Some of these clones like USA300 also emerged on other continents.
    Aim
    The aim of this study is to characterize CA-MRSA isolates among consecutive Staphylococcus aureus isolates collected in 2001, 2004 and 2006 from Chicago, IL.
    Methods
    Eighty consecutive Staphylococcus aureus isolates were collected in 2001, 2004 and 2006 from patients with serious invasive infections admitted at Cook County Hospital Chicago, IL. Twenty isolates were identified as CA-MRSA. These isolates were genotyped by multilocus sequence typing (MLST). DNA of these isolates were hybridized to a multistrain PCR product S. aureus microarray in collaboration with the University of London, UK.
    Results
    Surprisingly, MLST revealed that one CA-MRSA strain belonged to ST80, the others belonged to the common ST8 and ST5. Besides in Europe, ST80 was isolated only a few times in the northern part of Africa, but not on other continents, including the USA. The patient, of whom the isolate was collected, could not be linked to Europe or northern Africa. The gene-profile of the one ST80 isolate was compared with literature data for other ST80 isolates. The microarray hybridization gene-profile of the CA-MRSA ST80 strain from the USA was comparable with literature, although data are sparse. Like all ST80 isolates this isolate does not have any enterotoxines, but they all carry the Panton-Valentine leukocidin genes and the biofilm formation genes icaA and icaB. Yet it showed some minor differences in presence of adhesion proteins compared to literature data.
    Conclusion
    This is the first described ST80 isolate in the USA, which is most likely transferred from Europe. It demonstrated pandemic spread of a second CA-MRSA clone in addition to USA300 posing a public health threat.