Frequency of Mupirocin Resistant Staphylococcus aureus Strains Isolated From Nasal Carriers in Hospital Patients in Kermanshah

Background: : Staphylococcus aureus is a major nosocomial pathogen world wide. Mupirocin plays a crucial role in strategies designed to control outbreaks of S. aureus. Objectives: The aim of this study was to determine the frequency of mupirocin resistance in S. aureus strains isolated from nasal carriers among the hospitalized patients at Kermanshah Hospital, Iran. Patients and Methods: A total of 174 S. aureus isolates (sensitive and resistant to methicillin) were collected from the nasal anterior nares of hospitalized patients. All isolates were tested for mupirocin susceptibility by a disc diffusion method. The minimum inhibitory concentration (MIC) was determined by an E-test and they were also analyzed by a PCR for the presence of ileS-1 and ileS-2 genes. Results: Utilizing the disc diffusion agar method, E-test and PCR, all of the S. aureus strains tested were susceptible to mupirocin. In this study, the range of mupirocin MICs was determined to be between 0.064 and 4 ?g/ml. There was a significant association between MIC observed and multi-drug resistant (MDR) carriage (P value 0.04), and resistance to oxacillin (P value 0.004). Conclusions: This is a report of an initial survey of mupirocin resistance in S. aureus, in Kermanshah where the use of mupirocin is still limited. Perhaps the sensitivity of all isolates to mupirocin in this study is due to the less common usage of this antibiotic, especially in the form of nasal and site sample collections.