Genomic portrait of community-associated methicillin-resistant Staphylococcus aureus ST772-SCCmec V lineage from India

Abstract

BackgroundSignificant changes in the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) were recognised with the emergence of community-associated methicillin-resistant Staphylococcus aureus. However, studies on the molecular epidemiology and the genomic investigation of MRSA are limited in India. AimThe study was aims to understand the molecular epidemiology of MRSA causing bloodstream infection and also to investigate the origin and evolution of ST772 S. aureus isolated from India. MethodsA total of 233 non-repetitive MRSA isolates were screened for the presence staphylococcal cassette chromosome (SCCmec) types, multi-locus sequence types (MLST) and staphylococcal protein A (spa) types. Whole genome sequence data of ST772-SCCmec V (n = 32) isolates were generated and comparative analysis was performed. ResultsMLST analysis revealed ten different clonal complexes and three singletons. ST772 (27%), ST22 (19%) and ST239 (16%) were the predominant MRSA genotypes in causing bloodstream infection. The spa types were highly diverse. Phylogenetic analysis revealed that nearly three-fourth of the Indian STT72-SCCmec V isolates belongs to dominant (ST772-A2) and emerging subgroups (ST772-A3). A pattern of increasing antimicrobial resistance was noticed in the dominant and emerging subgroups. An integrated resistance plasmid encoding resistance clusters for beta-lactam (blaZ), macrolides (mphC, msrA), and aminoglycoside resistance (aphA-III, sat-4, aadE) was identified in all isolates, except four basal strains. ST772-SCCmec V was emerged on the Indian subcontinent in 1964 and diverged into a dominant subgroup in 1991. Furthermore, the expansion is likely to be associated with the acqusition of mobile genetic elements such as integrated resistance plasmid and SCCmec V (5C2) as well as the fixation of double serine mutation (S84L, S80Y) in the quinolone resistance determining region. ConclusionsST772 S. aureus have consistent virulence and resistance determinants which may results in successful survival in both community and hospital settings.