scholarly journals Some Synonymous and Nonsynonymous gyrA Mutations in Mycobacterium tuberculosis Lead to Systematic False-Positive Fluoroquinolone Resistance Results with the Hain GenoType MTBDRsl Assays

2017 ◽  
Vol 61 (4) ◽  
Author(s):  
Adebisi Ajileye ◽  
Nataly Alvarez ◽  
Matthias Merker ◽  
Timothy M. Walker ◽  
Suriya Akter ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Specific Resistance ◽  
Multidrug Resistant ◽  
Fluoroquinolone Resistance ◽  
Wild Type ◽  
Resistance Mutations ◽  
Content Type ◽  
Synonymous Mutations ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis

ABSTRACT In this study, using the Hain GenoType MTBDRsl assays (versions 1 and 2), we found that some nonsynonymous and synonymous mutations in gyrA in Mycobacterium tuberculosis result in systematic false-resistance results to fluoroquinolones by preventing the binding of wild-type probes. Moreover, such mutations can prevent the binding of mutant probes designed for the identification of specific resistance mutations. Although these mutations are likely rare globally, they occur in approximately 7% of multidrug-resistant tuberculosis strains in some settings.

scholarly journals Sequence Analysis of Fluoroquinolone Resistance-Associated GenesgyrAandgyrBin Clinical Mycobacterium tuberculosis Isolates from Patients Suspected of Having Multidrug-Resistant Tuberculosis in New Delhi, India

2016 ◽  
Vol 54 (9) ◽  
pp. 2298-2305 ◽  
Author(s):  
Ritu Singhal ◽  
Paul R. Reynolds ◽  
Jamie L. Marola ◽  
L. Elaine Epperson ◽  
Jyoti Arora ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Indian Subcontinent ◽  
Amino Acid Position ◽  
Multidrug Resistant ◽  
High Rate ◽  
Fluoroquinolone Resistance ◽  
Content Type ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Mdr Tb

Fluoroquinolones (FQs) are broad-spectrum antibiotics recommended for the treatment of multidrug-resistant tuberculosis (MDR-TB) patients. FQ resistance, caused by mutations in thegyrAandgyrBgenes ofMycobacterium tuberculosis, is increasingly reported worldwide; however, information on mutations occurring in strains from the Indian subcontinent is scarce. Hence, in this study, we aimed to characterize mutations in thegyrAandgyrBgenes of acid-fast bacillus (AFB) smear-positive sediments or ofM. tuberculosisisolates from AFB smear-negative samples from patients in India suspected of having MDR-TB. A total of 152 samples from patients suspected of having MDR-TB were included in the study. One hundred forty-six strains detected in these samples were characterized by sequencing of thegyrAandgyrBgenes. The extracted DNA was subjected to successive amplifications using a nested PCR protocol, followed by sequencing. A total of 27 mutations were observed in thegyrAgenes of 25 strains, while no mutations were observed in thegyrBgenes. The most common mutations occurred at amino acid position 94 (13/27 [48.1%]); of these, the D94G mutation was the most prevalent. ThegyrAmutations were significantly associated with patients with rifampin (RIF)-resistant TB. Heterozygosity was seen in 4/27 (14.8%) mutations, suggesting the occurrence of mixed populations with different antimicrobial susceptibilities. A high rate of FQ-resistant mutations (17.1%) was obtained among the isolates of TB patients suspected of having MDR-TB. These observations emphasize the need for accurate and rapid molecular tests for the detection of FQ-resistant mutations at the time of MDR-TB diagnosis.

scholarly journals Sulfamethoxazole Susceptibility of Mycobacterium tuberculosis Isolates from HIV-Infected Ugandan Adults with Tuberculosis Taking Trimethoprim-Sulfamethoxazole Prophylaxis

2015 ◽  
Vol 59 (9) ◽  
pp. 5844-5846 ◽  
Author(s):  
Sam Ogwang ◽  
Caryn E. Good ◽  
Brenda Okware ◽  
Mary Nsereko ◽  
Michael R. Jacobs ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Multidrug Resistant ◽  
Sub Saharan Africa ◽  
Content Type ◽  
Pulmonary Tb ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Sub Saharan

ABSTRACTAdditional drugs are needed for the treatment of multidrug-resistant tuberculosis (TB). Sulfamethoxazole has been shown to havein vitroactivity againstMycobacterium tuberculosis; however, there is concern about resistance given the widespread use of trimethoprim-sulfamethoxazole prophylaxis among HIV-infected patients in sub-Saharan Africa. Thirty-eight of 40Mycobacterium tuberculosisisolates (95%) from pretreatment sputum samples from Ugandan adults with pulmonary TB, including HIV-infected patients taking trimethoprim-sulfamethoxazole prophylaxis, were susceptible with MICs of ≤38.4 μg/ml.

scholarly journals Molecular Characterization of Multidrug-Resistant Mycobacterium tuberculosis Isolated in Nepal

2012 ◽  
Vol 56 (6) ◽  
pp. 2831-2836 ◽  
Author(s):  
Ajay Poudel ◽  
Chie Nakajima ◽  
Yukari Fukushima ◽  
Haruka Suzuki ◽  
Basu Dev Pandey ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Promoter Region ◽  
Multidrug Resistant ◽  
Content Type ◽  
Molecular Tests ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Mdr Tb ◽  
Substitution Mutations ◽  
Drug Resistant Strains

ABSTRACTDespite the fact that Nepal is one of the first countries globally to introduce multidrug-resistant tuberculosis (MDR-TB) case management, the number of MDR-TB cases is continuing to rise in Nepal. Rapid molecular tests applicable in this setting to identify resistant organisms would be an effective tool in reversing this trend. To develop such tools, information about the frequency and distribution of mutations that are associated with phenotypic drug resistance inMycobacterium tuberculosisis required. In the present study, we investigated the prevalence of mutations inrpoBandkatGgenes and theinhApromoter region in 158M. tuberculosisisolates (109 phenotypically MDR and 49 non-MDR isolates collected in Nepal) by DNA sequencing. Mutations affecting the 81-bp rifampin (RIF) resistance-determining region (RRDR) ofrpoBwere identified in 106 of 109 (97.3%) RIF-resistant isolates. Codons 531, 526, and 516 were the most commonly affected, at percentages of 58.7, 15.6, and 15.6%, respectively. Of 113 isoniazid (INH)-resistant isolates, 99 (87.6%) had mutations in thekatGgene, with Ser315Thr being the most prevalent (81.4%) substitution. Mutations in theinhApromoter region were detected in 14 (12.4%) INH-resistant isolates. The results from this study provide an overview of the current situation of RIF and INH resistance inM. tuberculosisin Nepal and can serve as a basis for developing or improving rapid molecular tests to monitor drug-resistant strains in this country.

scholarly journals Mode of Action of Clofazimine and Combination Therapy with Benzothiazinones against Mycobacterium tuberculosis

2015 ◽  
Vol 59 (8) ◽  
pp. 4457-4463 ◽  
Author(s):  
Benoit Lechartier ◽  
Stewart T. Cole
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Bacterial Load ◽  
Multidrug Resistant ◽  
Content Type ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Drug Resistant Strains ◽  
Transfer Chain

ABSTRACTClofazimine (CZM) is an antileprosy drug that was recently repurposed for treatment of multidrug-resistant tuberculosis. InMycobacterium tuberculosis, CZM appears to act as a prodrug, which is reduced by NADH dehydrogenase (NDH-2), to release reactive oxygen species upon reoxidation by O2. CZM presumably competes with menaquinone (MK-4), a key cofactor in the mycobacterial electron transfer chain, for its reduction by NDH-2. We studied the effect of MK-4 supplementation on the activity of CZM againstM. tuberculosisand found direct competition between CZM and MK-4 for the cidal effect of CZM, against nonreplicating and actively growing bacteria, as MK-4 supplementation blocked the drug's activity against nonreplicating bacteria. We demonstrated that CZM, like bedaquiline, is synergisticin vitrowith benzothiazinones such as 2-piperazino-benzothiazinone 169 (PBTZ169), and this synergy also occurs against nonreplicating bacteria. The synergy between CZM and PBTZ169 was lost in an MK-4-rich medium, indicating that MK-4 is the probable link between their activities. The efficacy of the dual combination of CZM and PBTZ169 was testedin vivo, where a great reduction in bacterial load was obtained in a murine model of chronic tuberculosis. Taken together, these data confirm the potential of CZM in association with PBTZ169 as the basis for a new regimen against drug-resistant strains ofM. tuberculosis.

scholarly journals Upregulation of the Phthiocerol Dimycocerosate Biosynthetic Pathway by Rifampin-Resistant,rpoBMutant Mycobacterium tuberculosis

2012 ◽  
Vol 194 (23) ◽  
pp. 6441-6452 ◽  
Author(s):  
Gregory P. Bisson ◽  
Carolina Mehaffy ◽  
Corey Broeckling ◽  
Jessica Prenni ◽  
Dalin Rifat ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Secondary Metabolites ◽  
Gene Networks ◽  
Polyketide Synthase ◽  
Multidrug Resistant ◽  
Wild Type ◽  
Transcriptional Responses ◽  
Content Type ◽  
Resistant Tuberculosis ◽  
Phthiocerol Dimycocerosate

ABSTRACTMultidrug-resistant tuberculosis has emerged as a major threat to tuberculosis control. Phylogenetically related rifampin-resistant actinomycetes with mutations mapping to clinically dominantMycobacterium tuberculosismutations in therpoBgene show upregulation of gene networks encoding secondary metabolites. We compared the expressed proteomes and metabolomes of two fully drug-susceptible clinical strains ofM. tuberculosis(wild type) to those of their respective rifampin-resistant,rpoBmutant progeny strains with confirmed rifampin monoresistance following antitubercular therapy. Each of these strains was also used to infect gamma interferon- and lipopolysaccharide-activated murine J774A.1 macrophages to analyze transcriptional responses in a physiologically relevant model. BothrpoBmutants showed significant upregulation of the polyketide synthase genesppsA-ppsEanddrrA, which constitute an operon encoding multifunctional enzymes involved in the biosynthesis of phthiocerol dimycocerosate and other lipids inM. tuberculosis, but also of various secondary metabolites in related organisms, including antibiotics, such as erythromycin and rifamycins.ppsA(Rv2931),ppsB(Rv2932), andppsC(Rv2933) were also found to be upregulated more than 10-fold in the BeijingrpoBmutant strain relative to its wild-type parent strain during infection of activated murine macrophages. In addition, metabolomics identified precursors of phthiocerol dimycocerosate, but not the intact molecule itself, in greater abundance in bothrpoBmutant isolates. These data suggest thatrpoBmutation inM. tuberculosismay trigger compensatory transcriptional changes in secondary metabolism genes analogous to those observed in related actinobacteria. These findings may assist in developing novel methods to diagnose and treat drug-resistantM. tuberculosisinfections.

scholarly journals Mutations inpepQConfer Low-Level Resistance to Bedaquiline and Clofazimine in Mycobacterium tuberculosis

2016 ◽  
Vol 60 (8) ◽  
pp. 4590-4599 ◽  
Author(s):  
Deepak Almeida ◽  
Thomas Ioerger ◽  
Sandeep Tyagi ◽  
Si-Yang Li ◽  
Khisimuzi Mdluli ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Cross Resistance ◽  
Loss Of Function ◽  
Content Type ◽  
Low Level ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis

ABSTRACTThe novel ATP synthase inhibitor bedaquiline recently received accelerated approval for treatment of multidrug-resistant tuberculosis and is currently being studied as a component of novel treatment-shortening regimens for drug-susceptible and multidrug-resistant tuberculosis. In a limited number of bedaquiline-treated patients reported to date, ≥4-fold upward shifts in bedaquiline MIC during treatment have been attributed to non-target-based mutations inRv0678that putatively increase bedaquiline efflux through the MmpS5-MmpL5 pump. These mutations also confer low-level clofazimine resistance, presumably by a similar mechanism. Here, we describe a new non-target-based determinant of low-level bedaquiline and clofazimine cross-resistance inMycobacterium tuberculosis: loss-of-function mutations inpepQ(Rv2535c), which corresponds to a putative Xaa-Pro aminopeptidase.pepQmutants were selected in mice by treatment with clinically relevant doses of bedaquiline, with or without clofazimine, and were shown to have bedaquiline and clofazimine MICs 4 times higher than those for the parental H37Rv strain. Coincubation with efflux inhibitors verapamil and reserpine lowered bedaquiline MICs against both mutant and parent strains to a level below the MIC against H37Rv in the absence of efflux pump inhibitors. However, quantitative PCR (qPCR) revealed no significant differences in expression ofRv0678,mmpS5, ormmpL5between mutant and parent strains. Complementation of apepQmutant with the wild-type gene restored susceptibility, indicating that loss of PepQ function is sufficient for reduced susceptibility bothin vitroand in mice. Although the mechanism by which mutations inpepQconfer bedaquiline and clofazimine cross-resistance remains unclear, these results may have clinical implications and warrant further evaluation of clinical isolates with reduced susceptibility to either drug for mutations in this gene.

scholarly journals A computational perspective on the dynamic behaviour of recurrent drug resistance mutations in the pncA gene from Mycobacterium tuberculosis

RSC Advances ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 2476-2486
Author(s):  
Taimoor Khan ◽  
Abbas Khan ◽  
Syed Shujait Ali ◽  
Shahid Ali ◽  
Dong-Qing Wei
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Causes Of Death ◽  
Dynamic Behaviour ◽  
Multidrug Resistant ◽  
Resistance Mutations ◽  
Drug Resistance Mutations ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Computational Perspective

Tuberculosis is still one of the top 10 causes of death worldwide, particularly with the emergence of multidrug-resistant tuberculosis.

scholarly journals Mycobacterium tuberculosis Mutations Associated with Reduced Susceptibility to Linezolid

2016 ◽  
Vol 60 (4) ◽  
pp. 2542-2544 ◽  
Author(s):  
Shuo Zhang ◽  
Jiazhen Chen ◽  
Peng Cui ◽  
Wanliang Shi ◽  
Xiaohong Shi ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Rapid Detection ◽  
Multidrug Resistant ◽  
Mechanisms Of Resistance ◽  
Content Type ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Mdr Tb

ABSTRACTLinezolid (LZD) has become increasingly important for the treatment of multidrug-resistant tuberculosis (MDR-TB), but its mechanisms of resistance are not well characterized. We isolated 32 mutants ofMycobacterium tuberculosiswith reduced susceptibility to LZD, which was accounted for byrrlandrplCmutations in almost equal proportions, causing lower and higher MICs, respectively. Our findings provide useful information for the rapid detection of LZD resistance for improved treatment of MDR-TB.

scholarly journals Determination of MIC Distribution and Epidemiological Cutoff Values for Bedaquiline and Delamanid in Mycobacterium tuberculosis Using the MGIT 960 System Equipped with TB eXiST

2015 ◽  
Vol 59 (7) ◽  
pp. 4352-4355 ◽  
Author(s):  
Peter M. Keller ◽  
Rico Hömke ◽  
Claudia Ritter ◽  
Giorgia Valsesia ◽  
Guido V. Bloemberg ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Multidrug Resistant ◽  
Wild Type ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Mdr Tb ◽  
Type Strains

ABSTRACTBedaquiline (Sirturo) and delamanid (Deltyba) have recently been approved by the regulatory authorities for treatment of multidrug-resistant tuberculosis (MDR-TB). Antimicrobial susceptibility testing is not established for either substance. On the basis of the use of the MGIT 960 system equipped with EpiCenter/TB eXiST, we determined a mean bedaquiline MIC for wild-type strains of 0.65 mg/liter (median, 0.4 mg/liter) and an epidemiological cutoff (ECOFF) of 1.6 mg/liter; for delamanid, a mean wild-type drug MIC of 0.013 mg/liter (median, 0.01 mg/liter) and an ECOFF of 0.04 mg/liter were determined.

Fidaxomicin has high in vitro activity against Mycobacterium tuberculosis

2021 ◽  
Author(s):  
Qing Sun ◽  
Shuqi Wang ◽  
Xinlei Liao ◽  
Guanglu Jiang ◽  
Hairong Huang ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Type Species ◽  
Multidrug Resistant ◽  
Alamar Blue ◽  
In Vitro Activity ◽  
Content Type ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Mdr Tb

This study aimed to evaluate whether the antibiotic fidaxomicin has in vitro activity against Mycobacterium tuberculosis (Mtb). 38 fully drug-sensitive Mtb strains and 34 multidrug-resistant tuberculosis (MDR-TB) strains were tested using the microplate alamar blue assay (MABA) method to determine the minimum inhibitory concentrations (MICs) for fidaxomicin and rifampicin. Fidaxomicin has high in vitro activity against Mtb and is a potential drug to treat Mtb, and MDR-TB infections in particular.

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