AUTHOR=Chouhan Deepak , Retnakumar R. J. , Devi T. Barani , Dharmaseelan Sanjai , Alexander Sneha Mary , Devadas Krishnadas , Chattopadhyay Santanu , Nair Gopinath Balakrish , Pillai Madhavan Radhakrishna 

TITLE=Unusually high clarithromycin resistance in Mycobacterium abscessus subsp. abscessus isolated from human gastric epithelium

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1193380

DOI=10.3389/fmicb.2023.1193380

ISSN=1664-302X

ABSTRACT=<p><italic>Mycobacterium abscessus</italic> subsp. <italic>abscessus</italic> is a rapidly growing facultative intracellular pathogen that usually infects human lung and skin epithelium. Recently, we and another group have shown that it also has the potential to colonize human gastric epithelium, but its significance with respect to gastric diseases remains unclear. Although <italic>Helicobacter pylori</italic> still remains the only definite gastric pathogen, recent studies have shown that <italic>M. abscessus</italic> subsp. <italic>abscessus</italic> also has the potential to colonize human gastric epithelium. <italic>M. abscessus</italic> subsp. <italic>abscessus</italic> is known to exhibit multidrug resistance and clarithromycin has been used as the drug of choice. We aimed to determine the clarithromycin resistance profile of 117 (74 rough and 43 smooth) gastric <italic>M. abscessus</italic> subsp. <italic>abscessus</italic> strains and to detect the point mutations in <italic>rrl</italic> and <italic>erm</italic> (41) genes conferring the resistance. Our data showed 79.48% (19 smooth and 74 rough) of <italic>M. abscessus</italic> subsp. <italic>abscessus</italic> strains were resistant to clarithromycin (MIC<sub>90</sub> ≤ 512 μg/mL), while 20.51% (24 smooth) were susceptible (MIC<sub>90</sub> ≤ 8 μg/mL). Nucleotide sequence analysis of the <italic>rrl</italic> gene with reference strains of <italic>M. abscessus</italic> subsp. <italic>abscessus</italic> did not show any mutation that is relevant to the clarithromycin resistance. However, analysis of <italic>erm</italic> (41) gene showed that <italic>M. abscessus</italic> subsp. <italic>abscessus</italic> strains, which were susceptible to clarithromycin had C, C, G, and C at their nucleotide positions 28, 159, 238, and 330, respectively, while the resistant strains showed T, T, A, and A at the same positions. Based on antibiogram and sequence analysis data we recommend further studies involving genomic analysis to identify the other genes involved in high clarithromycin resistance in gastric <italic>M. abscessus</italic> subsp. <italic>abscessus</italic> along with the mechanisms involved.</p>