Antibiotic resistance and typing of agr locus in Staphylococcus aureus isolated from clinical samples in Sanandaj, Western Iran

Objective(s): Infections by Staphylococcus aureus remain an important health problem. The aims were to detect mecA, staphylococcal cassette chromosome mec (SCCmec), accessory gene regulator (agr), and integrons in S. aureus and to investigate the relationship of agr types with antibiotic resistance of isolates. Materials and Methods: In this cross-sectional study, 70 S. aureus isolates were collected between December 2017 and May 2018 from clinical specimens of patients in two hospitals of Sanandaj, western Iran. Susceptibility was determined by disk diffusion for 9 antibiotics and by vancomycin E test. The mecA, classes 1-3 integrons, SCCmec I-V, and agr I-IV were detected by polymerase chain reaction. A P-value<0.05 was considered significant. Results: The most effective antibiotics were linezolid, vancomycin, and trimethoprim-sulfamethoxazole (above 90% sensitivity). Of the 70 isolates, 17.1% were methicillin-resistant S. aureus (MRSA), 8.6% carried class 1 integron, 11.4% carried mecA, 17.1% carried agr I, and 30% carried agr III. SCCmec III and SCCmecV were detected. An association was found between resistance to certain antibiotics and the presence of agr I (P-value<0.05). Conversely, the prevalence of agr III in susceptible strains was higher than non-susceptible strains, and no MRSA isolates belonged to agr III (P-value<0.05). Conclusion: These data suggest that agr activity may influence the resistance of S. aureus to antibiotics. Although the prevalence of mecA and integron was relatively low, the identification of such strains calls for serious health concerns; thus highlights the need to monitor drug resistance in S. aureus.