Macrolide-Lincosamide Resistance and Virulence Genes in Staphylococcus aureus Isolated from Clinical Specimens in Ardabil, Iran

Background & Objective: Staphylococcus aureus causes various hospital- and community-acquired infections. This study aimed to investigate the phenotypic and genotypic characteristics of erythromycin and inducible clindamycin resistance, virulence gene profiles, and spa types of S. aureus isolates collected from patients in Ardabil Province, Iran.Methods: A total of ۱۱۸ clinical S. aureus isolates, including ۵۰ (۴۲.۴%) methicillin-resistant S. aureus (MRSA) and ۶۸ (۵۷.۶%) methicillin-susceptible S. aureus (MSSA) strains, were investigated. Resistance patterns were determined by the disk diffusion method and minimum inhibitory concentration (MIC) test. Inducible macrolide-lincosamide-streptogramin B (iMLSB) resistance was detected using D-test method. The polymerase chain reaction (PCR) was used to identify the virulence and resistance-encoding genes. Additionally, the spa types of the isolates were determined using the PCR, followed by sequencing.Results: In total, ۴۹.۱% (۵۸/۱۱۸) and ۴۴% (۵۲/۱۱۸) of the isolates were resistant to erythromycin and clindamycin, respectively. Overall, ۱۳.۵% (۱۶/۱۱۸) of the isolates showed the iMLSB resistance phenotype. The ermC gene (۷۲.۴% [۴۲]) was the most frequent erythromycin resistance-encoding gene, followed by ermA (۶۰.۳% [۳۵]), ermB (۶۰.۳% [۳۵]), ermTR (۵۱.۷% [۳۰]), and msrA (۱۵.۵% [۹]) genes among erythromycin-resistant isolates. The virulence genes hla, hld, sea, LukS PV, tst, seb, sed, eta, sec, and etb were detected in ۹۳.۲%, ۷۴.۵%, ۷۰.۳%, ۳۲.۲%, ۲۹.۶%, ۱۷%, ۸.۵%, ۸.۵%, ۵.۹%, and ۴.۲% of the isolates, respectively. Ten different spa types were identified for ۵۸ erythromycin-resistant S. aureus strains, of which t۰۳۰ and t۰۷۸ types were the most common types.Conclusion: A high frequency of macrolide- and lincosamide-resistant S. aureus isolates with different genetic backgrounds of resistance and virulence may be  found  in patients in Ardabil Province, Iran.

Keywords:

iMLSB resistance Lincosamide , Macrolide , Spa typing , Staphylococcus aureus , Virulence genes