Methicillin-ResistantStaphylococcus aureus:Phylogenetic Relatedness Between European Epidemic Clones and Swiss Sporadic Strains

Abstract

We have compared the phylogenetic diversity of methicillin-resistant Staphylococcus aureus (MRSA) strains from Switzerland and their phylogenetic relationships with European epidemic clones, using multiprimer random amplification polymorphic DNA (RAPD). Strains included 24 European epidemic clones (59 strains), 66 sporadic strains isolated in Switzerland in 1996-1997, and 15 reference strains of five other Staphylococcus species. Similarity and clustering analysis with the Jaccard's coefficient showed that the maximum genetic distance between MRSA strains was 0.43, whereas the minimum genetic distance between the six Staphylococcus species was 0.97, indicating that the method permits phylogenetic hierarchization. The 24 MRSA clones reported to be epidemic in European countries during the 1990s were distributed into seven different genetic clusters with a maximum distance of 0.29 among them. This clustering pattern was confirmed by the analysis of a subset of MRSA strains by multilocus enzyme electrophoresis at 12 loci. Most of the sporadic Swiss strains were distributed into these seven different genetic clusters, together with the epidemic MRSA clones. This suggests that there is no phylogenetic cluster specific to epidemic clones of MRSA.

Emergence, Spread, and Characterization of Phage Variants of Epidemic Methicillin-Resistant Staphylococcus aureus 16 in England and Wales

“…Both of these strains were shown to be closely related to the United Kingdom EMRSA-16 prototypic strain (data not shown), with both similar phage patterns when typed at SaRS and similar SmaI macrorestriction patterns. More recently, a Swiss strain (Geneva clone 2) related to EMRSA-16 was reported, with one isolate having originated in Greece (9). EMRSA-16 has also been identified in Norway (29), Spain (25), and the United States (21), where it is reported to be the second most common U.S. healthcare-associated pulsed-field type.…”

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

“…), and related profiles were indicated by adding a number (A1, A2, B1, B2, etc). PFGE profiles of these strains were compared to a collection of European epidemic strains previously described (6). The type of the SCCmec was determined as previously described (38); selection of isolates was done in order to include for each year the first two to six isolates of each clone.…”

Reemergence of Gentamicin-Susceptible Strains of Methicillin-Resistant Staphylococcus aureus in France: a Phylogenetic Approach

“…We used a typing method, multiprimer randomly amplified polymorphic DNA (RAPD), which was validated to produce information on the phylogenetic relationships between isolates (2).…”

“…), and (iii) 12 Gen r and 8 Gen s strains isolated in 1996 and 11 Gen r strains isolated in 1990 from the National Reference Center for Staphylococcal Toxemia in Lyon, France. In addition, 24 strains isolated from other European countries were selected from a previous study and are representative of the diversity of MRSA observed (2).…”

“…Multiprimer RAPD typing consists of using the RAPD technique with 10 consecutively selected primers, as already described (2). In brief, DNA was extracted, purified, and quantified before its use for the PCR.…”