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

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.
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 Mupirocin-derived gene mutations provide multi-drug resistance in methicillin-resistant Staphylococcus aureus.