Genotypic and phenotypic characterization of virulence in methicillin resistant Staphylococcus aureus isolated from a local hospital of Ahmedabad, Gujarat, India.

BACKGROUND

Staphylococcus aureus is a causative agent of diseases ranging from skin and soft tissue infections to several other invasive diseases such as bacteraemia, osteomyelitis, and pneumonia, as well as various non-invasive diseases due to secretion of diverse array of virulence factors. The aim of this study was to establish a correlation between antibiotic resistance, virulence traits, genotypes and infections caused by MRSA in a local hospital of Ahmedabad, Gujarat, India.

METHOD: For this study, 118 S. aureus isolates were obtained from the Microbiology Department of Sheth L.G General Hospital, Ahmedabad, Gujarat, India during the period of March 2022 to September 2022. The isolates were subjected to antibiotic susceptibility, phenotypic characterization of virulence traits, genotypic characterization of adhesion and virulence genes as well as genotyping of agr and SCCmec types.

RESULTS

This study reports 55.93% isolates from males and 44.07% isolates from females. 88.98% of isolates were associated with cases of skin and soft tissue infections (SSTIs), one of the most common infections associated with S. aureus. All the isolates were multidrug resistant (MDR). Phenotypically, 95.76% of isolates were reported to be either strong or moderate biofilm producers, 94.07% of isolates showed strong or moderate lipolytic activity and 91.53% of isolates were β- haemolytic. Genotypically, adhesion genes, ebpS, eno, sarA, fnbA and cna were reported in 94.07%, 93.22%, 82.20%, 78.81% and 67.80% of isolates, respectively and virulence genes, spA, SE family, coa, pvl and tsst, were reported in 99.15%, 97.46%, 84.75%, 77.12% and 50% of isolates, respectively. agr typing and SCCmec classification revealed agr type I (61.02%) and SCCmec type III (35.59%) to be the most prevalent type. The antibiotic resistance, biofilm formation and presence of adhesion and virulence genes were found to be associated with agr type I and III and SCCmec type I, III and IV. A strong correlation was observed between isolates obtained from pus samples and agr type I, II and III, SCCmec type I, IA, II, III, IIIA, IIIB and IV, biofilm formation, haemolysis, lipolysis and prevalence of adhesion and virulence genes.

CONCLUSION

SSTIs was the most common infection associated with S. aureus. Maximum antibiotic resistance was reported against β lactam, fluoroquinolones and macrolides class of antibiotics. Majority of isolates were strong biofilm producers, β- hemolytic, lipolytic and belonged to agr type I and SCCmec type III. Isolates belonging to agr type I and III and SCCmec type I, III and IV were found to be more virulent.