Dissemination of high level mupirocin – resistant CC 22 - MRSA - IV in

Mupirocin is used for eradicating methicillin-resistant S. aureus (MRSA) nasal colonisation. A plasmid-borne gene, mupA, is associated with high-level mupirocin resistance. After the prevalence of mupA, encoding high-level mupirocin resistance, among all MRSA from a tertiary care centre in the German state of Saxony was approximately 1% for over 15 years (2000-2015), a sharp increase to nearly 20% was observed in 2016/2017. DNA microarray profiling revealed that this was due to the dissemination of a variant of CC22-MRSA-IV (“Barnim Epidemic Strain” or “UK-EMRSA-15”) that in addition to mecA harbours mupA, aacA-aphD and qacA, as well as, in most isolates, erm(C). In order to prevent therapy failures and a further spread of this strain, the use of mupirocin should be more stringently controlled and it should be guided by susceptibility testing. In addition, MRSA decolonisation regimens that rely on other substances such as on betaisodona, polyhexanide or octenidine should be considered.