Molecular Characterization of Staphylococcal cassette chromosome mec and Tetracycline Resistance genes in Clinical Isolates

Document Type : Original Article

Authors
Parisa Mirhosseini 1
Maryam Homayoon 2
1 M.Sc., Department of Biology, Zargh.C. Branch, Islamic Azad University, Zarghan, Iran.
2 Assistant Professor, Department of Microbiology, Zand Institute of Higher Education, Shiraz, Iran.
10.22034/zmm.2026.737079
Abstract
Background & Objectives: Staphylococcus species are major causes of hospital and community acquired infections worldwide. This study aimed to investigate the distribution of Staphylococcal cassette chromosome mec (SCCmec) types among clinical Staphylococcus isolates from Shiraz and evaluated their association with tetracycline resistance determinants. Understanding these resistance mechanisms is important for epidemiological surveillance and infection control.
Materials & Methods: In this cross-sectional study, 93 clinical Staphylococcus isolates were collected from different clinical specimens in Namazi hospital in Shiraz , Iran. Antimicrobial susceptibility testing was performed using the agar disk diffusion method and MIC method according to the CLSI guidelines. Polymerase chain reaction (PCR) was employed to detect tetracycline resistance genes (tetK and tetM) and to determine SCCmec types.
Results: Tetracycline resistance was detected in 51.61% of the examined Staphylococcus isolates. Molecular analysis identified the tetK and tetM genes in 38.70% and 41.30% of isolates, respectively. SCCmec type II was the predominant cassette type, and a significant association was observed between SCCmec type II and tetracycline resistance determinants.
Conclusion: Diverse SCCmec types were identified among clinical Staphylococcus isolates, with SCCmec type II being the predominant type. The high prevalence of tet genes indicates a substantial burden of tetracycline resistance. Continuous molecular surveillance is essential for monitoring the distribution of resistance determinants and SCCmec elements. Strengthening antimicrobial stewardship programs may help reduce the spread of resistant strains in healthcare settings.
Keywords
Staphylococcus
Molecular surveillance
SCCmec
tetK
tetM
MIC
Zand Molecular Microbiology
Volume 2, Issue 1
Winter 2026
Pages 15-27