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Delamanid, Bedaquiline, and Linezolid Minimum Inhibitory Concentration Distributions and Resistance-related Gene Mutations in Multidrug-resistant and Extensively Drug-resistant Tuberculosis in Korea.

ABSTRACT: BACKGROUND:Delamanid, bedaquiline, and linezolid have recently been approved for the treatment of multidrug- and extensively drug-resistant (MDR and XDR, respectively) tuberculosis (TB). To use these drugs effectively, drug susceptibility tests, including rapid molecular techniques, are required for accurate diagnosis and treatment. Furthermore, mutation analyses are needed to assess the potential for resistance. We evaluated the minimum inhibitory concentrations (MICs) of these three anti-TB drugs for Korean MDR and XDR clinical strains and mutations in genes related to resistance to these drugs. METHODS:MICs were determined for delamanid, bedaquiline, and linezolid using a microdilution method. The PCR products of drug resistance-related genes from 420 clinical Mycobacterium tuberculosis strains were sequenced and aligned to those of M. tuberculosis H37Rv. RESULTS:The overall MICs for delamanid, bedaquiline, and linezolid ranged from ?0.025 to >1.6 mg/L, ?0.0312 to >4 mg/L, and ?0.125 to 1 mg/L, respectively. Numerous mutations were found in drug-susceptible and -resistant strains. We did not detect specific mutations associated with resistance to bedaquiline and linezolid. However, the Gly81Ser and Gly81Asp mutations were associated with resistance to delamanid. CONCLUSIONS:We determined the MICs of three anti-TB drugs for Korean MDR and XDR strains and identified various mutations in resistance-related genes. Further studies are needed to determine the genetic mechanisms underlying resistance to these drugs.

SUBMITTER: Yang JS

PROVIDER: S-EPMC6056398 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Project description:ObjectivesPatients with highly resistant tuberculosis have few treatment options. Bedaquiline, pretomanid and linezolid regimen (BPaL) is a new regimen shown to have favourable outcomes after six months. We present an economic evaluation of introducing BPaL against the extensively drug-resistant tuberculosis (XDR-TB) standard of care in three epidemiological settings.DesignCost-effectiveness analysis using Markov cohort model.SettingSouth Africa, Georgia and the Philippines.ParticipantsXDR-TB and multidrug-resistant tuberculosis (MDR-TB) failure and treatment intolerant patients.InterventionsBPaL regimen. PRIMARY AND SECONDARY OUTCOME MEASURES: (1) Incremental cost per disability-adjusted life years averted by using BPaL against standard of care at the Global Drug Facility list price. (2) The potential maximum price at which the BPaL regimen could become cost neutral.ResultsBPaL for XDR-TB is likely to be cost saving in all study settings when pretomanid is priced at the Global Drug Facility list price. The magnitude of these savings depends on the prevalence of XDR-TB in the country and can amount, over 5 years, to approximately US$ 3 million in South Africa, US$ 200 000 and US$ 60 000 in Georgia and the Philippines, respectively. In South Africa, related future costs of antiretroviral treatment (ART) due to survival of more patients following treatment with BPaL reduced the magnitude of expected savings to approximately US$ 1 million. Overall, when BPaL is introduced to a wider population, including MDR-TB treatment failure and treatment intolerant, we observe increased savings and clinical benefits. The potential threshold price at which the probability of the introduction of BPaL becoming cost neutral begins to increase is higher in Georgia and the Philippines (US$ 3650 and US$ 3800, respectively) compared with South Africa (US$ 500) including ART costs.ConclusionsOur results estimate that BPaL can be a cost-saving addition to the local TB programmes in varied programmatic settings.

Project description:BACKGROUND:Linezolid has antimycobacterial activity in vitro and is increasingly used for patients with highly drug-resistant tuberculosis. METHODS:We enrolled 41 patients who had sputum-culture-positive extensively drug-resistant (XDR) tuberculosis and who had not had a response to any available chemotherapeutic option during the previous 6 months. Patients were randomly assigned to linezolid therapy that started immediately or after 2 months, at a dose of 600 mg per day, without a change in their background regimen. The primary end point was the time to sputum-culture conversion on solid medium, with data censored 4 months after study entry. After confirmed sputum-smear conversion or 4 months (whichever came first), patients underwent a second randomization to continued linezolid therapy at a dose of 600 mg per day or 300 mg per day for at least an additional 18 months, with careful toxicity monitoring. RESULTS:By 4 months, 15 of the 19 patients (79%) in the immediate-start group and 7 of the 20 (35%) in the delayed-start group had culture conversion (P=0.001). Most patients (34 of 39 [87%]) had a negative sputum culture within 6 months after linezolid had been added to their drug regimen. Of the 38 patients with exposure to linezolid, 31 (82%) had clinically significant adverse events that were possibly or probably related to linezolid, including 3 patients who discontinued therapy. Patients who received 300 mg per day after the second randomization had fewer adverse events than those who continued taking 600 mg per day. Thirteen patients completed therapy and have not had a relapse. Four cases of acquired resistance to linezolid have been observed. CONCLUSIONS:Linezolid is effective at achieving culture conversion among patients with treatment-refractory XDR pulmonary tuberculosis, but patients must be monitored carefully for adverse events. (Funded by the National Institute of Allergy and Infectious Diseases and the Ministry of Health and Welfare, South Korea; ClinicalTrials.gov number, NCT00727844.).

Project description:BackgroundUganda remains one of the countries with the highest burden of TB/HIV. Drug-resistant TB remains a substantial challenge to TB control globally and requires new strategic effective control approaches. Drug resistance usually develops due to inadequate management of TB patients including improper treatment regimens and failure to complete the treatment course which may be due to an unstable supply or a lack of access to treatment, as well as patient noncompliance.MethodsTwo sputa samples were collected from Xpert MTB/RIF® assay-diagnosed multi-drug resistant tuberculosis (MDR-TB) patient at Lira regional referral hospital in northern Uganda between 2020 and 2021 for comprehensive routine mycobacterial species identification and drug susceptibility testing using culture-based methods. Detection of drug resistance-conferring genes was subsequently performed using whole-genome sequencing with Illumina MiSeq platform at the TB Supranational Reference Laboratory in Uganda.ResultsIn both isolates, extensively drug-resistant TB (XDR-TB) was identified including resistance to Isoniazid (katG p.Ser315Thr), Rifampicin (rpoB p.Ser450Leu), Moxifloxacin (gyrA p.Asp94Gly), Bedaquiline (Rv0678 Glu49fs), Clofazimine (Rv0678 Glu49fs), Linezolid (rplC Cys154Arg), and Ethionamide (ethA c.477del). Further analysis of these two high quality genomes revealed that this 32 years-old patient was infected with the Latin American Mediterranean TB strain (LAM).ConclusionsThis is the first identification of extensively drug-resistant Mycobacterium tuberculosis clinical isolates with bedaquiline, linezolid and clofazimine resistance from Uganda. These acquired resistances were because of non-adherence as seen in the patient's clinical history. Our study also strongly highlights the importance of combating DR-TB in Africa through implementing next generation sequencing that can test resistance to all drugs while providing a faster turnaround time. This can facilitate timely clinical decisions in managing MDR-TB patients with non-adherence or lost to follow-up.

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Delamanid, Bedaquiline, and Linezolid Minimum Inhibitory Concentration Distributions and Resistance-related Gene Mutations in Multidrug-resistant and Extensively Drug-resistant Tuberculosis in Korea.

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