Resistance pattern of mupirocin in methicillin-resistant Staphylococcus aureus in trauma patients and comparison between disc diffusion and E-test for better detection of resistance in low resource countries

Abstract

Introduction:Mupirocin is an effective antibiotic for elimination of methicillin-resistant Staphylococcus aureus (MRSA) from nasal colonization and has been used to control outbreaks. Current reports show an increasing trend of resistance to this antibiotic.Objective:This study was conducted to analyze the resistance pattern of MRSA to mupirocin among the patients admitted following trauma to an apex trauma care center of India and to compare the efficacy between two methods of antimicrobial sensitivity testing.Materials and Methods:A total of 150 isolates of MRSA from various clinical samples of trauma patients over a period of 2 years were included in this study. These strains were confirmed for MRSA using VITEK® 2 Compact and the Clinical Laboratory Standard Institute disc diffusion methods. The mupirocin susceptibility of the strains was tested by using E-test and 5 μg mupirocin disc in parallel each time, and the results were compared.Results:Clear zones of inhibition were observed in both tests. Though, good correlation was observed between the disc diffusion and E-tests in >98%, E-test showed a tendency to show lower minimum inhibitory concentration (MIC) in the remaining. These finding did not affect the final interpretation or outcomes. Of the total 150 strains, 138 (92%) showed sensitivity with the zone size in the range of 30-45 mm by 5 μg disc; rest (8%) showed sensitivity with the zone in the range of 18-30 mm by 5 μg disc, but 143 (95%) showed MIC ≤ 0.094 μg/ml and 8 (5%) gave MIC ≤ 0.75 μg/ml but ≥0.094 μg/ml by E-test. However, when both tests were compared, 5 (3.3%) showed zone size between 14 and 25 mm with ≤0.75 but >0.25 μg/ml MIC; 7 (5%) falling between 25 and 30 mm zone with MIC of ≤0.25 but >0.094 μg/ml and 138 (92%) showed zone >30 mm with MIC ≤0.094 but >0.064 μg/ml.Conclusions:All the MRSA isolates in our study were sensitive to mupirocin which is an encouraging finding. Though good screening for sensitivity can be done with 5 μg mupirocin disc, E-test provides a much clear and accurate results in clinical set-up. Hence, disc test can be used in resource poor countries and supplemented with E-test when needed.

Promising anti-microbial effect of apple vinegar as a natural decolonizing agent in healthcare workers

“…These findings corroborate the results of other previous studies from Iran, Nepal, and India [32,34,35]. Mupirocin resistance is being reported in many parts of the world in Korea 5%, India 6%, China 6.6%, Spain 11.3%, USA 13.2%, Trinidad Tobago 26.1%, and Turkey 45% [36]. Our MRSA isolates showed LL MR (36.4%), MICs of Mupirocin ranged from 0.25 to 32 µg/ml.…”

Influence of borderline cefepime MIC on the outcome of cefepime-susceptible Pseudomonas aeruginosa bacteremia treated with a maximal cefepime dose: a hospital-based retrospective study

“…However, some study results suggested E test provides equal or more clear and accurate results in clinical set-up [24, 25]. Furthermore, the mechanisms for increasing cefepime MICs in P. aeruginosa isolates remain unclear.…”

“…Our study has the limitations for being a retrospective design with the treatment decisions dependent on the physicians’ judgments and the hospital antimicrobial stewardship program [ 23 ]. However, some study results suggested E test provides equal or more clear and accurate results in clinical set-up [ 24 , 25 ]. Furthermore, the mechanisms for increasing cefepime MICs in P. aeruginosa isolates remain unclear.…”

Mupirocin Resistance in Staphylococcus aureus isolated from the Anterior Nares of Health Care Workers, in a Tertiary Care Hospital

“…Resistance to mupirocin is reported to be 5% in Korea, 6% in India, 6.6% in China, 11.3% in Spain, 13.2% in United States of America, 26.1% in Trinidad Tobago and 45% in Turkey (Rajkumari et al, 2014). Although the wide spread use of mupirocin has led to resistance, the other causes of mupirocin resistance are: concentration of the drug in deeper layers of skin is less than in nose, irregular and ineffective application (mupirocin need to be massaged back on the nose for at least 1 min), reinfection due to a different strain with resistance and rarely by aerosol spread especially in dermatology and burns ward (Cookson, 1998).…”