Dissemination of high-level mupirocin-resistant CC22-MRSA-IV in Saxony
A recent study by Stefan Monecke and colleagues from Germany in collaboration with David Coleman and Anna Shore from the TCD School of Dental Science investigated a sharp increase in mupirocin resistant methicillin-resistant Staphylococcus aureus (MRSA) belonging to the CC22 strain in the Saxony region of Germany. CC22-MRSA-IV have predominated in Irish hospitals for the last decade. Mupirocin is an important antibiotic used worldwide for eradicating S. aureus nasal colonization among hospitalised patients. Mupirocin-resistant MRSA have been identified frequently among Irish MRSA, including among isolates belonging to the CC22-MRSA-IV clone. Resistant isolates harbour mupA, a mobile mupirocin resistance gene that is readily transferable between strains. The results of this study showed that mupirocin resistance was relatively rare among MRSA in Saxony (approximately 1%) between 2000 and 2015. However, this rose to 20% during 2016/17 in Saxony due to the dissemination of a variant of CC22-MRSA-IV harbouring mupA. The German isolates were similar to but not identical to Irish isolates. The study concluded that colonizing MRSA isolates should be tested for susceptibility to mupirocin before being used to decolonize patients to preserve the effectiveness of this important antibiotic.
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