Prevalence and genomic structure of bacteriophage phi3 in human derived livestock-associated MRSA isolates from 2000 to 2015

To investigate the role of phi3 in the adaptation process of MRSA CC398 to the human host, the proportion of phi3-carrying MRSA spa-CC011 was systematically assessed for a period of 16 years. Overall,21 of 632 isolates were found to harbour phage phi3. Characterization of the phi3 genomes revealed 12 different phage types ranging in size from 40,712 kb up to 44,064 kb with four hitherto unknown integration sites (genes or intergenic regions)and several modified bacterial attachment (attB) sites.