Overexpression of eis without a mutation in promoter region of amikacin- and kanamycin-resistant Mycobacterium tuberculosis clinical strain

Abstract

BackgroundAminoglycosides such as amikacin and kanamycin are effective injectable second-line drugs for treatment of multidrug-resistant tuberculosis. Molecular mechanisms underlying aminoglycoside resistance are not well understood. We have previously identified the amikacin- and kanamycin-resistant M. tuberculosis MT433 clinical strain, of which all known mutations related to resistance have not been found. Drug efflux pump is one of reported resistance mechanisms that might play a role in aminoglycoside resistance.MethodsThe expression levels of sixteen putative efflux pump genes, including eis and one regulator gene, whiB7, of MT433 in the presence of kanamycin were determined using the reverse transcription-quantitative PCR method. The effects of upregulated genes on amikacin and kanamycin resistance were investigated by overexpression in M. tuberculosis H37Ra strain.ResultsUpon kanamycin exposure, other than whiB7 and eis that were found extremely overexpressed, two drug efflux pump genes, namely Rv1877 and Rv2846c, showed specifically high-level of expression in M. tuberculosis MT433 strain. However, direct effect of overexpressed Rv1877 and Rv2846c on amikacin and kanamycin resistance could not be demonstrated in M. tuberculosis H37Ra overexpressed strain.ConclusionsOur finding demonstrated that overexpression of eis could occur without any mutations in the promoter region and be detectable in clinical isolate. This might be a consequence of overexpressed whiB7, resulting in amikacin and kanamycin resistance in M. tuberculosis MT433 strain.Electronic supplementary materialThe online version of this article (10.1186/s12941-018-0285-6) contains supplementary material, which is available to authorized users.

Association Between 16S rRNA Gene Mutations and Susceptibility to Amikacin in Mycobacterium avium Complex and Mycobacterium Abscessus Clinical Isolates

“…Two e ux pump genes were also overexpressed in the amikacin-and kanamycin-resistant M. tuberculosis clinical isolate MT433, which lacked mutations, but overexpression of these genes in M. tuberculosis H37Ra strain did not increase the MIC against amikacin 30 . However, overexpression of eis in M. tuberculosis isolate MT433 was detected, suggesting that eis might be associated with kanamycin resistance 30 . There are limited studies about the basis for low-level amikacin resistance in M. tuberculosis, and further studies are also needed to understand the mechanism of low-level amikacin resistance in MAC.…”

Comprehensive analysis of protein acetyltransferases of human pathogen Mycobacterium tuberculosis

“…Both Eis enzymes from M. tuberculosis and M. smegmatis acetylated capreomycin and several lysine-containing compounds, and this acetylation of capreomycin was found at the ɛ-amine of the β-lysine side chain [61]. Recently, Sowajassatakul et al found that overexpression of eis could occur without a mutation in the promoter region and be detectable in amikacin- and kanamycin-resistant M. tuberculosis clinical strain [62]. Ye et al demonstrated that Eis proteins have the ability to acetylate many arylalkylamines, and are a novel family of arylalkylamine N-acetyltransferase AANAT (EC 2.3.1.87) [63].…”

Association between 16S rRNA gene mutations and susceptibility to amikacin in Mycobacterium avium Complex and Mycobacterium abscessus clinical isolates

“…The multidrug-resistant M. tuberculosis clinical isolate M7, which was additionally resistant to amikacin, had no rrs mutations but overexpressed pstB , an efflux pump gene 29 . Two efflux pump genes were also overexpressed in the amikacin- and kanamycin-resistant M. tuberculosis clinical isolate MT433, which lacked mutations, but overexpression of these genes in M. tuberculosis H37Ra strain did not increase the MIC against amikacin 30 . However, overexpression of eis in M. tuberculosis isolate MT433 was detected, suggesting that eis might be associated with kanamycin resistance 30 .…”

“…Two efflux pump genes were also overexpressed in the amikacin- and kanamycin-resistant M. tuberculosis clinical isolate MT433, which lacked mutations, but overexpression of these genes in M. tuberculosis H37Ra strain did not increase the MIC against amikacin 30 . However, overexpression of eis in M. tuberculosis isolate MT433 was detected, suggesting that eis might be associated with kanamycin resistance 30 . There are limited studies about the basis for low-level amikacin resistance in M. tuberculosis , and further studies are also needed to understand the mechanism of low-level amikacin resistance in MAC.…”