Comparative genome analysis of global and Russian strains of community-acquired methicillin-resistant Staphylococcus aureus sequence type 22, a “Gaza clone”

Abstract In this study, we identified the relationship between the genetic lineage of CA-MRSA ST22 from Russia and other regions. Sixty ST22 isolates were characterized through whole genome sequencing. For evaluating the phylogenetic relationships of Russian isolates with the global ST22 population, we analyzed 1283 genomes obtained from NCBI GenBank. The phylogenetic tree of the ST22 global population consisted of three main clusters. The first (cluster A) was represented by EMRSA-15 isolates, the second (cluster B) by heterogeneous isolates from different regions harboring different sets of virulence genes, and the third (cluster C) by isolates from Middle East previously recognized as “Gaza clone” and similar isolates from Russia. The presence of the toxic shock syndrome toxin (tsst) and elastin-binding protein S (ebpS) genes and of the hypothetical proteins NCTC13616_00051 and NCTC13616_00047 were the most useful factors in discriminating ST22 lineages. Although the “Gaza clone” CA-MRSA was mainly recovered from carriers, its widespread occurrence is a cause of concern. Differentiation of the “Gaza clone” from other lineages of MRSA is necessary for planning infection control measures.