Determination and characterization of heteroresisitant vancomycin intermediate staphylococcus aureus from a tertiary care centre

Abstract

The study aimed to characterize the hVISA isolated from the patient identified with MRSA bacteremia. It was also proposed to identify the association between invasive MRSA isolates and the virulence factors PVL and sasX. The potential synergy between oxacillin and vancomycin was also investigated in this study. The study was also intended to understand the epidemiology of MRSA in causing BSI and the genomic comparison of ST772 S. aureus contributes for evolution and expansion. To summarise, increased resistance to clindamycin and trimethoprim-sulfamethoxazole greatly limits the treatment option preferred for treating CA-MRSA infections. It is imperative that high proportion of hVISA is observed among MRSA with the vancomycin MIC of and#8805; 1.5 and#956;g/ml. Increased glycopeptide usage might serve as selection pressure for emergence of hVISA. Clonal association of hVISA, indicates the need of prevention control in practice. The proportion of PVL carrying strains are almost similar between CA and HA-MRSA. The PVL encoding phages and#934;IND772 and and#981;sa119 contributes for the widespread dissemination of PVL in S. aureus strains. In-vitro synergy testing revealed that the combination of beta-lactam plus vancomycin is more bactericidal than vancomyin alone. The presence invasion factors encoding gene sesI and colonisation-invasion virulence factor sasX promotes colonisation mediated invasive MRSA infection and may worsen the clinical outcome. Among MRSA, ST772, ST22 and ST239 were observed as the major clone. The community acquired clone ST772 and the hospital acquired clone are ST239 more multi-drug resistant. The MRSA lineage ST772-SCCmec V is observed as the established multi-drug resistant and highly virulent MRSA clone in India. Acquisition of integrated resistance plasmid and smaller SCCmec variant SCCmec V contributes for the fitness cost to ST772 MRSA strains. Expansion of ST772 strains into hospital is alarming and should be closely monitored for infection prevention control practices. newline