Genomic Structure of ST8-t008 USA300 and USA300-LV MRSA in the Rhine- Neckar Region, Germany, 2012-2018

Abstract Methicillin-resistant Staphylococcus aureus (MRSA) ST8-t008 of the pulsotype USA300 and the Latin American Variant (USA300-LV) are the predominant virulent MRSA clonal lineage on the American continent. In Europe, the occurrence of USA300 or USA300-LV has often been related to international travel or outbreaks in hospitals. The replacement of local epidemic MRSA clones by these hypervirulent clones has not been demonstrated so far in Europe. We aimed to gain insight into the genetic relatedness of ST8-t008 MRSA encountered in previous studies in the Rhine-Neckar Region, Germany and ST8-t008 MRSA from other geographic regions. We compared 19 ST8-t008 MRSA isolated between 2012 and 2018 to publicly available sequences of ST8-t008 MRSA from travellers returning from the tropics and to USA300 and USA300-LV that were previously encountered in Europe. We identified 73.7% (n=14/19) of our local ST8-t008 MRSA being related to USA300 and 26.3% (n=5/19) belonging to the USA300-LV cluster. Four suspected transmission clusters were identified without any evidence for in-hospital transmission. The genetic relatedness of these local strains to publicly available sequences of ST8-t008 MRSA of other parts of Europe and to MRSA of travellers returning from the tropics points to multiple introductions into Germany. However, four suspected transmission clusters may be an indication of transmission in the community.