Evaluation of high-level of mupirocin resistance among clinical isolates of methicillin-resistant staphylococcus aureus from Shiraz, Iran (2008-2009)

Background: The spread of methicillin-resistant Staphylococcus aureus (MRSA) is a major concern in medical centers. These isolates are considered in serious infections and nosocomial outbreaks worldwide. Mupirocin is one of the most important antibiotics used topically for the treatment of various staphylococcal and streptococcal skin infections. We aimed to use a combination of phenotypic and genotypic methods to evaluate the prevalence of mupirocin resistance among MRSA clinical isolates which had previously been collected during the period 2008-2009 in Shiraz, Iran. Methods: This study was performed on a total of 167 clinical isolates of MRSA from Shiraz teaching hospitals. The isolates were identified as S. aureus using standard microbiologic procedures and confirmed as MRSA isolates by 30 μg cefoxitin discs and mecA gene detection. All isolates were investigated for the mupirocin resistance by mupirocin discs 5 μg and the presence of mupA gene by PCR. Results: Antibacterial susceptibility tests against mupirocin disc 5 μg and PCR analysis for totally 167 MRSA clinical isolates showed no resistance to mupirocin. Conclusion: In summary, fortunately regarding to absence of resistance to mupirocin among all the studied MRSA isolates, this resistance seems is not a threatening factor in studied hospitals. However, generalized our findings to whole hospitals wards and Shiraz general population afford larger sample size and periodic surveillance in further studies for detecting mupirocin resistance.