Spa gene-based molecular typing of nasal methicillin-susceptible staphylococcus aureus from patients and health-care workers in a dialysis center in southeast Iran.

Staphylococcus aureus is an important infectious agent in hemodialysis patients. This study was conducted to determine the frequency of S. aureus nasal carriage in hemodialysis patients (HD) and health-care workers (HCW) at the main dialysis center of Bam city, located in southeast of Iran. In this cross-sectional study, a total of 52 nasal swabs were obtained from health-care workers and hemodialysis patients to detect methicillin-sensitive S. aureus (MSSA) isolates. The resistance to different antibacterial agents was determined by disk diffusion method. Also, Panton-Valentine Leukocidin (PVL) - encoding gene as well as Staphylococcal protein A (spa) type were determined. The nasal carriage rate of S. aureus was found to be 24.4% and 18.8% in patients on hemodialysis and health-care workers, respectively. Among identified isolates, no methicillin-resistant S. aureus (MRSA) was found. Only two MSSA isolates (16.7%) were resistant to trimethoprim/sulfamethoxazole. One isolate (8.6%) was positive for pvl gene. Moreover, 8 spa types were found. According to BURP analysis, six out of the 12 S. aureus isolates (50%) belonged to the same clone, indicating a prevalence of a major clone among MSSA in carriage, including patients and HCW. Mupirocin is still the appropriate drug for reducing nasal colonization in our setting. Accumulation of isolates from patients and staff in one spa clonal complex is alarming for the necessity of more serious infection control in this center. Therefore, it is necessary to screen patients and health-care workers as a health priority, in order to prevent cross transmission.