Historic methicillin-resistant Staphylococcus aureus: expanding current knowledge using molecular epidemiological characterization of a Swiss legacy collection

A study examining methicillin-resistant Staphylococcus aureus (MRSA) from 1965 to 1987 found 17 sequence types (STs) among 451 historic Swiss MRSA isolates. The study compared these isolates with publicly available international and local genomes. The results showed that most isolates represented ST247-MRSA-I, followed by ST7844, a novel single locus variant of ST239. Early MRSA were predominantly from clonal complex 8, and from 1980 to the end of the twentieth century, CC22, CC5, and CC8 were present both locally and internationally. The combined analysis of 1761 historic and contemporary MRSA isolates revealed novel STs and provided insight into the lineage flux between Swiss-German and international MRSA.