CC BY-NC-ND 4.0 · J Lab Physicians 2023; 15(03): 450-461
DOI: 10.1055/s-0043-1764483
Original Article

Spectrum of Virulence Factors in Clinical Isolates of Staphylococcus aureus and Prevalence of SCCmec Types in Methicillin-Resistant Staphylococcus aureus in a Tertiary Care Center

Rhea Michelle J. Khodabux
1   Department of Microbiology, Sri Ramachandra Institute of Higher Education and Research (SRIHER), Porur, Chennai, Tamil Nadu, India
Shanthi Mariappan
1   Department of Microbiology, Sri Ramachandra Institute of Higher Education and Research (SRIHER), Porur, Chennai, Tamil Nadu, India
Uma Sekar
1   Department of Microbiology, Sri Ramachandra Institute of Higher Education and Research (SRIHER), Porur, Chennai, Tamil Nadu, India
› Author Affiliations
Funding This study was supported by the Founder chancellor Shri N.P.V. Ramasamy Udayar fellowship, provided by Sri Ramachandra Institute of Higher Education and Research.


Background Methicillin-resistant Staphylococcus aureus (MRSA) is a widely recognized multidrug-resistant bacteria presenting a major therapeutic challenge to clinicians. Staphylococcus aureus possesses a number of pathogenicity factors that attribute to the severity of infections. This study was undertaken to investigate the common virulence genes in clinical isolates of Staphylococcus aureus, determine their antimicrobial susceptibility profile, and to characterize the staphylococcal cassette chromosome mec (SCCmec) types among MRSA in a tertiary care center.

Materials and Methods A total of 133 clinical isolates were included in this study. Susceptibility to various antibiotics was determined by disc diffusion method. Methicillin resistance was screened using cefoxitin disc; mecA and mecC genes were detected using polymerase chain reaction (PCR). PCR was done to detect 12 virulence factors such as hla, hlb, fnbA, fnbB, sea, seb, sec, icaA, clfA, tst, pvl, and eta. SCCmec typing was done by multiplex PCR.

Results Of the 133 clinical isolates, 54 (40.6%) were MRSA. The most common virulence gene detected was hlb (61.6%), hla (39%), and fnbA (37%). SCCmec type I was the most predominant. Mortality rate of 6.7% was observed among patients with staphylococcal infections. Univariate analysis of mortality associated virulence genes did not reveal any significant association between virulence genes and mortality.

Conclusion The distribution of virulence genes is similar in both MRSA and methicillin-sensitive Staphylococcus aureus. MRSA belongs to the SCCmec types I to IV. Possession of multiple virulence factors and multidrug resistance profile makes Staphylococcus aureus a formidable pathogen in clinical settings.

Publication History

Received: 15 August 2022

Accepted: 03 January 2023

Article published online:
27 March 2023

© 2023. The Indian Association of Laboratory Physicians. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (

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