Identification of Gene Mutation Patterns Obtained from Resistance to Mupirocin in Methicillin-Resistant Staphylococcus Aureus Clinical Strains, Using High-Resolution Melting (HRM) Method

Abstract

Background: Effective antibiotics on the translation pathway, such as mupirocin, may cause gene mutations in methicillin-resistant Staphylococcus aureus in long-term. Using high-sensitivity methods plays an important role in identifying these bacteria. Our goal was to identify these mutations using high-resolution melting (HRM) curve of DNA analysis. Methods: Resistance to mupirocin was identified using disc microdilution plate method in according to the Clinical and Laboratory Standards Institute (CLSI) guideline. mupA gene amplification in the isolates of methicillin-resistant Staphylococcus aureus was done using polymerase chain reaction (PCR). Then, analysis was performed using StepOne Software and HRM software. Sequencing was used as gold-standard method for confirming of the results. Findings: Out of 162 Staphylococcus aureus isolates, 83 (51.32%) were methicillin resistant. Among methicillin-resistant Staphylococcus aureus isolates, 47 (52.80 %) showed high level resistance to mupirocin carrying mupA. The most and lowest resistance was observed for penicillin (79.62%) and ceftazidime (6.17%), respectively. Moreover, all of multi-drug resistant (MDR) isolates were mupirucin resistant, too. Among mupirocin-resistant Staphylococcus aureus, wound samples were the most prevalent. Besides, isolates obtained from wound and blood demonstrated the highest mutation in A and G bases. Meaningful association was observed between the type of clinical sample and mutation rate, and resistance to mupirocin and methicillin (P < 0.05). Conclusion: Mupirocin-derived gene mutations provide multi-drug resistance in methicillin-resistant Staphylococcus aureus.

Keywords

• Mupirocin
• Methicillin resistance
• Staphylococcus aureus
• Mutation
• DNA melting