Multilocus sequence typing and antibiotic resistant patterns of the meticillin-resistant Staphylococcus aureus isolates from different clinical specimens

Abstract

Backgrounds: Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging threat worldwide. Community-associated-MRSA strains differ from hospital-acquired MRSA strains in their genetic backgrounds, pathogenicity, and antibiotic susceptibilities. Although few studies have reported the epidemiology of the different community-associated-MRSA and hospital-acquired-MRSA clones present, there are insufficient data available on MRSA characteristics in Iran. The present cross-sectional study was conducted to explore the prevalence of MRSA, the antimicrobial susceptibility of the strains, and the molecular epidemiology of such MRSA isolates from a hospital in Tabriz, Iran. Methods: S. aureus isolates were collected from patients with clinical signs and symptoms of infection admitted to Imam Reza Hospital, from September 2016 to March 2017 in Tabriz, Iran. Standard conventional biochemical tests for identification of the isolates were performed on colonies from primary cultures. The antibiotic susceptibility testing was performed using the standardized Kirby–Bauer disc-diffusion method on Mueller–Hinton agar. All methicillin-resistant isolates were archived for subsequent molecular tests, including PCR for mecA gene and multilocus sequence typing. Results: Among 39 S. aureus isolates enrolled, 33.3% (13/39) were identified as MRSA strains. Antibiotic susceptibilities to erythromycin, ciprofloxacin, and clindamycin, were measured as, 48.7, 46.2, and 35.9%, respectively. All of the 39 isolates were susceptible to vancomycin and linezolid. Sequence type (ST)-238 was the predominant clone (15.3%), and ST585, ST1, ST88, ST45, ST158, ST1097, ST2373, and ST2873 were other detected sequence type. In addition, two undetermined sequence type (a sequence type was not matched to any sequence type identified) were detected in this study. Conclusion: ST238 strains, which were previously not found as MRSA, could now widely distribute in Iranian population. In addition, the resistance rate of MRSA strains against multiple classes of antibiotics should be considered when selecting empirical antibiotics for MRSA infections in Iran.