The molecular epidemiology of MRSA in Malta and the description of a Maltese epidemic MRSA strain

Malta has one of the highest incidences of methicillin-resistant Staphylococcus aureus (MRSA) in Europe. However, there is only limited typing data available. In order to analyse the local situation, forty-five isolates from the Mater Dei Hospital in Msida, Malta, were characterised using diagnostic microarrays. The most common strain was ST22-MRSA-IV, also known as UK-EMRSA-15 (30 isolates). Sporadic strains included ST36/39-MRSA-II (UK-EMRSA-16, two isolates), PVL-positive ST80-MRSA-IV (European Clone, one isolate), ST228-MRSA-I (Italian Clone/South German Epidemic Strain, one isolate) and ST239-MRSA-III (Vienna/Hungarian/Brazilian Epidemic Strain, one isolate). Ten isolates belonged to a novel clonal complex 5, spa-type t002 strain. This strain carries genes from a SCCmec IV element (mecA, delta mecR, ugpQ, dcs, ccrA2 and ccrB2), novel alleles of ccrA/B and a fusidic acid resistance element Q6GD50 (BX571857.1:SAS0043). It also harboured the gene for enterotoxin A (sea) and the egc enterotoxin locus, as well as (in nine out of ten isolates) genes encoding the toxic shock syndrome toxin (tst1) and enterotoxins C and L (sec, sel). While the presence of the other MRSA strains suggests foreign importation because of intense travel activities between Malta and various European countries, so far this strain appears to be restricted to Malta yet. Introduction: Similar to other Southern European countries, Malta has a very high prevalence of MRSA. However, to our knowledge there is only one published study describing typing data of MRSA isolates from Malta (Gould et al., 2008) indicating the presence of ST22-MRSA-IV, of ST36-MRSA-II and of another strain which had a novel PFGE pattern, but which was not described in further detail.