Comparative analysis of Methicillin-resistant Staphylococcus aureus through whole genome sequencing in the largest tertiary care hospital in Peshawar, Pakistan.

Methicillin-resistant Staphylococcus aureus (MRSA) is a globally disseminated antibiotic-resistant pathogen and causes mild to severe infections. The population structure of MRSA is highly clonal and individual genetic clones harbor specific plasmid, and determinants for antibiotic resistance and virulence, therefore, whole genome sequencing (WGS) of five MRSA isolates of the predominant genetic lineage was performed to gain insight into the most prevalent endemic strains. Sequencing libraries were arranged in accordance with the Nextera XT DNA Library Prep Guide (Illumina). WGS was performed on Illumina NextSeq 500 platform with 2×151bp using a NextSeq Mid-Output Kit. The sequenced genome was characterized for spa type, MLST type, SCCmec type, plasmid, antibiotic resistance gene, and virulence gene by publicly available bioinformatics tools on the website of the Center for Genomic Epidemiology. All the isolates were characterized as ST8/t064-SCCmecIVa(2B) clones of MRSA and, A total of 13 resistance genes, 11 virulence genes, and 6 types of plasmids were identified in the sequenced isolates of MRSA, furthermore, the sequenced isolates showed a similar pattern of distribution for antibiotic resistance genes and virulence genes. WGS revealed that the isolates are genetically closely related and showed a similar pattern of distribution for different genetic markers, therefore, these strains could be an accidental case cluster or cluster of an outbreak.