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Microbiology and Biotechnology Letters


Molecular and Cellular Microbiology  |  Microbial Genetics, Physiology and Metabolism

Microbiol. Biotechnol. Lett.

Received: March 24, 2021; Revised: July 17, 2021

Detection of inducible clindamycin resistance genes (ermA, ermB, and ermC) in Staphylococcus aureus and Staphylococcus epidermidis

Mohammad Javad Mazloumi 1, Reza Akbari 2 and Saber Yousefi 3*

Urmia University of Medical Sciences, Urmia, Iran

Correspondence to :
Saber Yousefi, Department of Microbiology and Virology, Faculty of Medicine, Urmia University of Medical Sciences, 11th Km of Serow Road, Urmia, Iran [5714783734]
Tel : +98 44 3277 0698 Ext. 213, Fax : +98 44 3278 0800, E-mail :


The aim of the present study was to survey the frequency of D-phenotypes, inducible resistance genes (ermA, ermB and ermC), and msrA gene in Staphylococcus aureus and Staphylococcus epidermidis strains. A total of 172 bacterial isolates, which were identified based on standard tests, were examined in this study. Antibiotic susceptibility was determined by disk diffusion method, and all isolates were evaluated with respect to D-phenotypes. The presence of ermA, ermB, ermC, and msrA genes was also investigated by PCR assay. Linezolid showed the greatest antibacterial activity against beta-lactam-resistant S. aureus and S. epidermidis isolates. The frequency of R-phenotypes among S. aureus and S. epidermidis strains was 35.8% and 46.2%, respectively. Based on the findings, ermB, ermC and msrA genes were detected in 100% of S. aureus and S. epidermidis strains, which is indicative of HD phenotype and constitutive resistance. The ermB and ermC genes were the most common genes among methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. epidermidis (MRSE) strains, respectively. Distribution of inducible resistance genes in S. aureus and S. epidermidis strains, and possibly other species, leads to increased constitutive resistance to erythromycin, clindamycin, and other similar antibiotics. Therefore, it can be challenging to treat infections caused by resistant strains.

Keywords: D-phenotypes, Staphylococcus aureus, Inducible resistance, Staphylococcus epidermidis, Constitutive resistance

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