aureus clonal clusters suggests horizontal transmission of the SC

aureus clonal clusters suggests horizontal transmission of the SCCmec element has also occurred. SCCmec typing and spa typing and DNA microarray results also suggests horizontal transfer Sirolimus of SCCmec elements has occurred into the same CC on more than one occasion. Although several SCCmec elements have been acquired by multiple S. aureus clones from which many CA-MRSA clones have emerged, only a few clones have successfully adapted to the WA community environment. Between July

2009 to June 2010 4,691 MRSA were referred to ACCESS Typing and Research of which 3,931 were characterized as CA-MRSA. Overall 84% (3,024) of isolates were from clinical infections and the 16% (907) from colonized patients. Approximately 88% of CA-MRSA were identified as WA1 (40%), WA2 (24%) and WA3 (8%). For most clones, including WA4 find more and WA5 only a few isolates were detected. (http://​www.​public.​health.​wa.​gov.​au/​3/​896/​3/​camrsa.​pm). For many slv and dlv CA-MRSA only a small

number of isolates have been detected suggesting changes in the housekeeping genes may have conferred a fitness cost or did not allow the SCCmec element to be maintained. For example WA45 and WA57 are slvs of ST1 and their SCCmec and spa type and DNA microarray profile suggest they have evolved from WA1 (Figure 2). WA45 was first identified in 2006 and WA57 in 2007. Although WA1 has become the most successful CA-MRSA clone in the WA community only one isolate of WA45 and two isolates of WA56 have so far been identified (http://​www.​public.​health.​wa.​gov.​au/​3/​896/​3/​camrsa.​pm). Six PVL positive pandemic CA-MRSA clones (plus three closely related clones) have been isolated in WA: Bengal Bay CA-MRSA (ST772-V [5C2]/t3387), USA300 MRSA (ST8-IVc [2B]/t008), SWP CA-MRSA (ST30-IVc [2B]/t019), Taiwan CA-MRSA (ST59-V [5C2&5]/t437 and the slv ST952-V [5C2&5]/t1950), European CA-MRSA (ST80-IVc [2B]/t044 and the slvs, ST583-IVc [2B]/t044 and ST728-IVc [2B]/t044), and the Queensland CA-MRSA (ST93-IVa [2B]/t202). The epidemiology of the USA300 and Taiwan CA-MRSA clones in WA and the Queensland and SWP CA-MRSA clones in Australia have previously been reported [18, 31, 32]. Patients colonized or infected with

the Bengal Bay clone have been observed to be epidemiologically linked to Indian healthcare workers (unpublished data). The USA300, European, Taiwanese and Bengal Bay CA-MRSA clones are not Tyrosine-protein kinase BLK frequently isolated in WA. This may be due, in part, to WA Health Department infection control interventions applied to patients who are colonized or infected with international PVL positive pandemic clones. A seventh pandemic clone has recently been identified. The DNA microarray profile and the SCCmec element of the PVL negative ST398-V [5C2&5] is indistinguishable from the pandemic ST398 clone initially isolated from pigs and pig farmers in the Netherlands [39]. Only one isolate, from a patient with travel outside of Australia, has been identified in WA.

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