Background: Mupirocin is an antibacterial drug and it is used for topical application either alone or along with other antiseptics, in areas where ever infections or colonization of methicillin-resistant Staphylococcus aureus (MRSA) are found. Enhanced use of mupirocin ointment these days for local application has led to the rise in data of its resistance. Many carriers and patients are treated inappropriately due to lack of sensitivity testing and improper reporting for mupirocin and development of different levels of resistance in these strains. Due to the lack of next level treatment possibilities, we need to report sensitivity accurately, record prevalence of resistant strains, and figure out the cause of resistance.
Objective: We carried out this study to demonstrate levels of mupirocin resistance in MRSA strains isolated from patients samples and to check the resistance pattern of these strains to other antibacterial, in our hospital located in Delhi, North India.
Materials and Methods: The study is framed as prospective type and performed on the strains of MRSA collected from the different samples from outpatient departments and inpatient departments from January 2017 to December 2017. Out of 221 Staphylococcus aureus collected from different clinical specimens, 113 isolates were confirmed as MRSA strains. Two of the suggested methods were selected to detect mupirocin resistance: Disk diffusion method by 5 μg disc and microbroth dilution method.
Results: From our 113 MRSA isolates, resistance for mupirocin was noted in 16 (14.15%) isolates when subjected to disk diffusion and microbroth dilution test. These 16 strains showed varied level of resistance. High-level resistance was shown by 4 (3.5%) isolates and 12 (10.6%) isolates were found as low-level resistant (MuL). Mupirocin resistant MRSA isolates showed higher antibiotic resistance to erythromycin (81.26% vs. 78.76%), clindamycin (56.25% vs. 42.47%), linezolid (12.50% vs. 7.90%), and tigecycline (6.25% vs. 6.19%) as compared to MRSA strains. Not even single MRSA isolates were identified as vancomycin-resistant strain.
Conclusion: Both high- and low-level mupirocin-resistant MRSA was found in high numbers from these patients. It is recommended that routine test must be performed to detect resistance for mupirocin subsequent to the detection of MRSA colonization among visitors, patients, and health care workers and its isolation from local sites. Treatment and decolonization of mupirocin-resistant strains are mandatory to reduce infection and spread in hospital after having done proper sensitivity testing only.
Key words: Methicillin-resistant Staphylococcus aureus; Mupirocin; Level of Resistance
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