MRSA SPA-TYPE T032 OVERTAKES MRSA SPA-TYPE T037 AS THE PREDOMINANT CLONAL STRAIN: PRELIMINARY FINDINGS FROM A MALAYSIAN TERTIARY HOSPITAL.

Abstract

Intro: Community and hospital-acquired strains of Methicillin-resistant Staphylococcus aureus (MRSA) continue to pose a threat worldwide. Molecular epidemiological studies conducted worldwide continue to demonstrate shifts in predominantly circulating MRSA clones peculiar to their centres or countries that have the propensity to cause infection in hospitals and the community. We aimed to detect our hospital's predominantly circulating MRSA clonal strain in 2016 and 2018 by spa typing to compare with predominant clones reported previously in our and other Malaysian hospitals. Methods: We conducted spa typing on 58 randomly selected, non-repetitive confirmed MRSA isolates collected from bloodstream infections in Hospital Canselor Tuanku Muhriz (HCTM) from 2016 (37 isolates) and 2018 (21 isolates). Extracted and purified DNA target sequences were amplified and sequenced using the method and primers previously described. The gene fragments were analysed using Ridom StaphType software to assign the spa types. We compared the clonal strains by spa type with local MRSA clones reported previously. Findings: The predominant MRSA clonal strain isolated was spa-type t032 in 2016 (83.8%, n=31) and 2018 (76.2%, n=16) from our hospital, identified in the literature as the European invasive strain. The remaining isolates detected were spa-type t020, t670, t022 and t304 (from 2016) and t189, t304, t315, t701 and t718 (from 2018). We did not detect spa-type t037 among the isolates, reported previously as the predominant MRSA spa type between 2009 and 2013 in several other Malaysian hospitals, including ours. Discussion: This preliminary data suggests that the predominantly circulating MRSA clonal strains have changed throughout the recent decade in Malaysian hospitals, likely contributed by mechanisms promoting their sustainability and ability to replace other strains, besides hospital infection control factors. Conclusion: Further investigation is warranted to elucidate these unknown mechanisms in light of the continuing evolution of MRSA strains and continued surveillance of genotypes, virulence factors and antimicrobial susceptibility patterns.