A real-time PCR assay for rapid identification of inducible and acquired clarithromycin resistance in Mycobacterium absc
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RESEARCH ARTICLE
Open Access
A real-time PCR assay for rapid identification of inducible and acquired clarithromycin resistance in Mycobacterium abscessus Meenu Kaushal Sharma1,2* , Yanni La3, Debra Janella1 and Hafid Soualhine1,2
Abstract Background: Mycobacterium abscessus is a rapidly growing mycobacteria involved in severe infections of the lung, skin, or soft tissue. Macrolides such as clarithromycin are the recommended first line drugs for treatment of M. abscessus infections. However, M. abscessus has dual mechanisms of resistance to macrolides, making treatment by macrolides difficult. A functional erm(41) gene confers for inducible resistance while acquired mutations on the 23S rRNA rrl gene confer for constitutive resistance. Methods: We have developed a real-time PCR assay to detect both inducible and acquired resistance to clarithromycin, and compared the results to traditional erm(41) and rrl sequencing and phenotypic susceptibility testing using Sensititre™ plates. Results: Of the total 126 M. abscessus isolates tested, truncated erm(41) was found in 23/126 (18.3%) of the samples, 27/126 (21.4%) had a T28C mutation in erm(41), and 2/126 (1.6%) had an acquired A2058C mutation in rrl. The phenotypic results correlated with the expected sequencing results in 121/126 samples (96%). Phenotypic testing compared to real-time PCR resolved 2 of these discrepancies by showing the existence of both erm(41) alleles in the isolates that sequencing missed. One culture was found to be mixed with two M. abscessus subsp. as per hsp65 sequencing and 2 isolates had discordance between molecular and phenotypic results. It was presumed that 3 isolates showed discrepancy between sequencing and real-time PCR, but one culture was mixed and other 2 detected both alleles by real-time PCR leading to 100% concordance when compared to sequencing. Conclusion: In conclusion, real-time PCR is more accurate for detection of both acquired and induced clarithromycin resistance, specifically when mixed genic profiles are present in a sample. Keywords: Mycobacterium abscessus, Real-time PCR, erm(41), Clarithromycin
* Correspondence: [email protected] 1 National Reference Centre for Mycobacteriology, National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington St, R3E 3R2 Winnipeg, Canada 2 Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included i
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