Unusual Spread of a Penicillin-Susceptible Methicillin-Resistant Staphylococcus aureus Clone in a Geographic Area of Low Incidence

Abstract

We describe the unusual spread of a penicillin-susceptible methicillin-resistant Staphylococcus aureus (MRSA) clone in hospitals in western Switzerland, where the incidence of MRSA is usually low. During a 2-year period, this clone had been responsible for several outbreaks and had been isolated from >156 persons in 21 institutions. Molecular typing by pulsed-field gel electrophoresis (PFGE) demonstrated that all of these isolates belonged to the same clone. In 1 of the outbreaks, involving 30 cases, the clone was responsible for at least 17 secondary cases. In contrast, during the period of the latter outbreak, 9 other patients harboring different MRSA strains, as assessed by PFGE, were hospitalized in the same wards, but no secondary cases occurred. These observations suggest that this clone, compared with other MRSA strains, had some intrinsic factor(s) that contributed to its ability to disseminate and could thus be considered epidemic.

Changing Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in a Small Geographic Area over an Eight-Year Period

“…At least three more clones should be added to this restricted list to cover Northern European countries: the EMRSA-15 (ST 22; SCCmec IV), EMRSA-16 (ST 36; SCCmec II), and Berlin (ST 45; SCCmec IV) clones (23). It is hypothesized that these clones are particularly transmissible and/or well adapted to the hospital environment (9,13). New strains with particular virulence were recently found to disseminate in the community (CA-MRSA).…”

Successful control of methicillin-resistant Staphylococcus aureus in a spinal cord injury center: a 10-year prospective study including molecular typing

“…Comparison with Swiss epidemiologic strains isolated over the same observation period 14,15 revealed no strain homology. Thus, vigorous application of the guidelines for prevention of nosocomial transmission limited intra-hospital spread to only nine patients in an SCI clinic over a 10-year period.…”

“…Control strain C was an epidemic strain having spread in the western part of Switzerland 15 (kindly provided by DS Blanc, CHUV, Lausanne, Switzerland). The dendrograms were calculated by the unweighted pair group method using arithmetic averages (UPGMA).…”

Epidemiological Validation of Pulsed-Field Gel Electrophoresis Patterns for Methicillin-Resistant Staphylococcus aureus

“…PFGE typing was carried out in each center with the same technique (3,10). Plugs of genomic DNA were obtained by lysis with lysostaphin, followed by a treatment with proteinase K. The DNA was digested with the enzyme SmaI, according to the manufacturer's recommendations.…”