Second-line Injectable Drugs Research Articles

Acquired bedaquiline resistance during the treatment of drug-resistant tuberculosis: a systematic review.

BackgroundDrug-resistant tuberculosis (DR-TB) is considered to be a public health threat and is difficult to cure, requiring a lengthy treatment with potent, potentially toxic drugs. The novel antimicrobial agent bedaquiline has shown promising results for patients with DR-TB, improving the rate of culture conversion and reducing TB-related mortality. However, increasing numbers of cases with acquired bedaquiline resistance (ABR) have been reported in recent years.MethodsThis systematic review aimed to assess the frequency of ABR and characteristics of patients acquiring it. Studies showing data on sequential bedaquiline drug-susceptibility testing in patients treated with a bedaquiline-containing regimen were included. The databases CENTRAL, PubMed and Embase were manually searched, and 866 unique records identified, eventually leading to the inclusion of 13 studies. Phenotypic ABR was assessed based on predefined MIC thresholds and genotypic ABR based on the emergence of resistance-associated variants.ResultsThe median (IQR) frequency of phenotypic ABR was 2.2% (1.1%–4.6%) and 4.4% (1.8%–5.8%) for genotypic ABR. Among the studies reporting individual data of patients with ABR, the median number of likely effective drugs in a treatment regimen was five, in accordance with WHO recommendations. In regard to the utilization of important companion drugs with high and early bactericidal activity, linezolid was included in the regimen of most ABR patients, whereas the usage of other group A (fluoroquinolones) and former group B drugs (second-line injectable drugs) was rare.ConclusionsOur findings suggest a relevant frequency of ABR, urging for a better protection against it. Therefore, treatment regimens should include drugs with high resistance-preventing capacity through high and early bactericidal activity.

Direct detection of resistance to fluoroquinolones/SLIDs in sputum specimen by GenoType MTBDRsl v.2.0 assay A study from Eastern Uttar Pradesh, India

BackgroundAccording to World Health Organization (WHO), drug-resistant tuberculosis (DR-TB) is a major contributor to antimicrobial resistance globally and continues to be a public health threat. Annually, about half a million people fall ill with DR-TB globally. The gradual increase in resistance to fluoroquinolones (FQs) and second-line injectable drugs (SLIDs), poses a serious threat to effective TB control and adequate patient management. Therefore, WHO suggests the use of GenoType MTBDRsl v.2.0 assay for detection of multiple mutations associated with FQs and SLIDs. Hence, the study was conducted to determine the prevalence of resistance to FQs and SLIDs by comparing direct GenoType MTBDRsl v.2.0 assay with phenotypic drug susceptibility testing (DST).MethodsThe study was conducted on 1320 smear positive sputum samples from a total of 2536 RR-TB, confirmed by GeneXpert MTB/RIF. The smear positive specimens were decontaminated, and DNA extraction was performed. Furthermore, the extracted DNA was used for GenoType MTBDRsl v.2.0 assay. While 20% of the decontaminated specimens were inoculated in Mycobacterium growth indicator tube (MGIT) for drug susceptibility testing (DST).ResultsOut of 1320 smear positive sputum samples, 1178 were identified as Mycobacterium tuberculosis complex (MTBC) and remaining were negative by GenoType MTBDRsl v.2.0 assay. Of the 1178 MTBC positive, 26.6% were sensitive to both FQs and SLIDs, whereas 57.3% were only FQs resistant and 15.9% were resistant to both FQs and SLIDs. Further DST of 225 isolates by liquid culture showed that 17% were sensitive to both FQs and SLIDs, 61.3% were only FQs resistant and 21.3% were resistant to both. The specificity for FQs and SLIDs was 92.31% and 100% whereas sensitivity was 100% respectively by GenoType MTBDRsl v.2.0 assay in direct sputum samples.ConclusionsOur study clearly suggests that GenoType MTBDRsl v.2.0 assay is a reliable test for the rapid detection of resistance to second-line drugs after confirmation by GeneXpert MTB/RIF assay for RR-TB. Though, high rate FQ (ofloxacin) resistance was seen in our setting, moxifloxacin could be used as treatment option owing to very low resistance.

CBNAAT Based Identification and Demographic Pattern of Drug Resistant Mycobacterium Tuberculosis in South Kashmir, India- a One Year Retrospective Study

India is the highest TB burden country in the world having an estimated incidence of 26.9 lakh cases in 2019. With a population of 1.32 billion, India has the highest burden of drug resistant TB (DR-TB) in the world. North zone of India is the second highest MDR-TB prevalent zone after the West zone of India. MDR TB treatment involves prolonged treatment with injectable second-line drugs, associated with more adverse effects, suboptimal treatment outcomes and higher risks of mortality compared to patients with drug-sensitive TB and those with lesser resistant forms of TB.
 Materials methods: This retrospective study was conducted in the department of Microbiology Government Medical College Anantnag, data was analyzed from March 2017 to February 2018. Non-sterile specimens were processed by Modified Petroff Method. Sterile specimens were concentrated by centrifugation and smear and cultures was inoculated from the sediment. CBNAAT assay was performed by Gene Xpert (Cepheid) 4 system according to the manufacturers’ recommendations.
 Results: Of the total 1497 clinically suspected tuberculosis specimens collected, 1370 (91.5%) were pulmonary and 127 (8.5%) were presumptive extra pulmonary tuberculosis received from different anatomical sites. Maximum clustering of cases was seen in 10-20 years age group. Out of the total 1497 samples 200 were CBNAAT confirmed Mycobacterium Tuberculosis positive samples. In which 155 were pulmonary and 45 were extra pulmonary. The average percentage positivity rate (i.e. percentage of MTB positive samples out of total samples tested) was 13.3% (200/1497). Rifampicin resistance (RR-TB) was seen in 5.5% (11/200) samples. Out of the samples detected positive (200): 155 were pulmonary samples and out of these 155 pulmonary samples 8 were found to be RR MTB 5.1% (8/155). Also out of the 200 positive samples 45 were extra pulmonary and out of these 45 extra pulmonary samples 3 were found to be RR MTB 6.6% (3/45).
 Conclusion: In this study we found that in our region 5.5% cases of TB were RR-TB, 3.2% were new cases and 13% RR-TB was seen in previously treated cases of MTB. The screening of drug resistance has to be expanded to offer universal DST including expanded DST .The second and most important activity is to strengthen drug resistance surveillance under the various national programs with inclusion of laboratories in the private sector as well. The state level regional studies also give us the opportunity to plan and execute intervention prioritization, based on the drug resistance trends observed.

Evidence-based Definition for Extensively Drug-Resistant Tuberculosis.

Rationale: Until 2020, extensively drug-resistant tuberculosis (XDR-TB) was defined as TB with resistance to rifampicin and isoniazid (multidrug-resistant TB [MDR-TB]), any fluoroquinolone (FQ), and any second-line injectable drug (SLID). In 2019, the World Health Organization issued new recommendations for treating patients with drug-resistant TB, substantially limiting the role of SLIDs in MDR-TB treatment and thus putting the definition of XDR-TB into question. Objectives: To propose an up-to-date definition for XDR-TB. Methods: We used a large data set to assess treatment outcomes for patients with MDR-TB exposed to any type of longer regimen. We included patients with bacteriologically confirmed MDR-TB and known FQ and SLID resistance results. We performed logistic regression to estimate the adjusted odds ratios (aORs) for an unfavorable treatment outcome (failure, relapse, death, loss to follow-up), and estimates were stratified by the resistance pattern (FQ and/or SLID) and group A drug use (moxifloxacin/levofloxacin, linezolid, and/or bedaquiline). Measurements and Main Results: We included 11,666 patients with MDR-TB; 4,653 (39.9%) had an unfavorable treatment outcome. Resistance to FQs increased the odds of an unfavorable treatment outcome (aOR, 1.91; 95% confidence interval [CI], 1.63-2.23). Administration of bedaquiline and/or linezolid improved treatment outcomes regardless of resistance to FQs and/or SLIDs. Among patients with XDR-TB, compared with persons receiving no group A drug, aORs for an unfavorable outcome were 0.37 (95% CI, 0.20-0.69) with linezolid only, 0.40 (95% CI, 0.21-0.77) with bedaquiline only, and 0.21 (95% CI, 0.12-0.38) with both. Conclusions: Our study supports a new definition of XDR-TB as MDR-TB and additional resistance to FQ plus bedaquiline and/or linezolid and helps assess the adequacy of this definition for surveillance and treatment choice.

Assessment of the GenoType MTBDRsl VER 2.0 compared to the phenotypic drug susceptibility testing and whole genome sequencing for the rapid detection of resistance to fluoroquinolone and second-line injectable drugs among rifampicin-resistant Mycobacterium tuberculosis isolates.

Molecular techniques have considerable advantages for rapid detection, a reduction of infectiousness, prevention of further resistance development and surveillance of drug-resistant TB. MTBDRsl VER 2.0 was used to detect resistance to second-line anti-tuberculosis drugs on 35 rifampicin-resistant M. tuberculosis (RR-MTB) isolates compared to the minimum inhibitory concentrations (MICs) and whole genome sequencing (WGS). The MTBDRsl VER 2.0 (Hain Life Science, Nehren, Germany) and WGS (San Diego, CA, USA) were performed for tracing mutations in resistant-related genes involved in resistance to fluoroquinolone (FLQ) and second-line injectable drugs. The broth microdilution method using 7H9 Middlebrook media supplemented with OADC was used to determine the MICs. The MTBDRsl VER 2.0 correctly detected 5/6 (83.3%) of FLQ-resistant strains. The MUT1 A1401G (seven strains) and MUT2 G1484T (one strain) mutations in rrs gene were detected in eight AMK/KAN/CAP-resistant strains. Four low-level KAN-resistant strains with the G-10A/C-12T (three strains) and eis C-14T (one strain) mutations in eis gene was diagnosed using MTBDRsl VER 2.0. Five errors were found in detecting resistance to kanamycin and capreomycin compared to the phenotypic drug susceptibility testing and WGS. Failling wild-type bands without improved mutant bands did not indicate a reliable resistance. WGS could efficiently resolve the discrepancies of the results. MTBDRsl showed better performance in detecting XDR strains than pre-XDR.

Multidrug-resistant tuberculosis imported into low-incidence countries-a GeoSentinel analysis, 2008-2020.

Early detection of imported multidrug-resistant tuberculosis (MDR-TB) is crucial, but knowledge gaps remain about migration- and travel-associated MDR-TB epidemiology. The aim was to describe epidemiologic characteristics among international travellers and migrants with MDR-TB. Clinician-determined and microbiologically confirmed MDR-TB diagnoses deemed to be related to travel or migration were extracted from GeoSentinel, a global surveillance network of travel and tropical medicine clinics, from January 2008 through December 2020. MDR-TB was defined as resistance to both isoniazid and rifampicin. Additional resistance to either a fluoroquinolone or a second-line injectable drug was categorized as pre-extensively drug-resistant (pre-XDR) TB, and as extensively drug-resistant (XDR) TB when resistance was detected for both. Sub-analyses were performed based on degree of resistance and country of origin. Of 201 patients, 136 had MDR-TB (67.7%), 25 had XDR-TB (12.4%), 23 had pre-XDR TB (11.4%) and 17 had unspecified MDR- or XDR-TB (8.5%); 196 (97.5%) were immigrants, of which 92 (45.8%) originated from the former Soviet Union. The median interval from arrival to presentation was 154days (interquartile range [IQR]: 10-751days); 34.3% of patients presented within 1month after immigration, 30.9% between 1 and 12months and 34.9% after ≥1year. Pre-XDR- and XDR-TB patients from the former Soviet Union other than Georgia presented earlier than those with MDR-TB (26days [IQR: 8-522] vs. 369days [IQR: 84-827]), while patients from Georgia presented very early, irrespective of the level of resistance (8days [IQR: 2-18] vs. 2days [IQR: 1-17]). MDR-TB is uncommon in traditional travellers. Purposeful medical migration may partly explain differences in time to presentation among different groups. Public health resources are needed to better understand factors contributing to cross-border MDR-TB spread and to develop strategies to optimize care of TB-infected patients in their home countries before migration.

Evaluation of drug-resistant tuberculosis treatment outcome in Portugal, 2000-2016.

Treatment of drug-resistant tuberculosis (TB), which is usually less successful than that of drug-susceptible TB, represents a challenge for TB control and elimination. We aimed to evaluate treatment outcomes and to identify the factors associated with death among patients with MDR and XDR-TB in Portugal. We assessed MDR-TB cases reported for the period 2000–2016, using the national TB Surveillance System. Treatment outcomes were defined according to WHO recommendations. We identified the factors associated with death using logistic regression. We evaluated treatment outcomes of 294 MDR- and 142 XDR-TB patients. The treatment success rate was 73.8% among MDR- and 62.7% among XDR-TB patients (p = 0.023). The case-fatality rate was 18.4% among MDR- and 23.9% among XDR-TB patients. HIV infection (OR 4.55; 95% CI 2.31–8.99; p < 0.001) and resistance to one or more second-line injectable drugs (OR 2.73; 95% CI 1.26–5.92; p = 0.011) were independently associated with death among MDR-TB patients. HIV infection, injectable drug use, past imprisonment, comorbidities, and alcohol abuse are conditions that were associated with death early on and during treatment. Early diagnosis of MDR-TB and further monitoring of these patients are necessary to improve treatment outcome.

Outcomes of Multidrug-Resistant Tuberculosis Treated With Bedaquiline or Delamanid.

Since 1 September 2016, bedaquiline and delamanid have been administered for the treatment of patients with multidrug-resistant/rifampicin-resistant tuberculosis after the official approval in South Korea. This study aimed to assess and compare the final treatment outcomes of patients who received bedaquiline with those of patients who received delamanid. This is a nationwide cohort study of patients with multidrug-resistant/rifampicin-resistant tuberculosis in whom bedaquiline or delamanid was administered from 1 September 2016 to 28 February 2018, after receiving the official approval in South Korea. Patients were classified into the bedaquiline and delamanid group according to the first used drug. We evaluated and compared the final treatment outcomes between the groups. During the study period, 284 patients with multidrug-resistant/rifampicin-resistant tuberculosis were approved to use bedaquiline or delamanid and 260 were included in the final analysis; 119 (45.8%) and 141 patients (54.2%) were classified into bedaquiline and delamanid groups, respectively. Among them, 30 patients (11.5%) exhibited additional resistance to second-line injectable drugs, 94 patients (36.2%) had additional resistance to fluoroquinolones, and 37 patients (14.2%) had resistance to both drugs. The overall treatment success rate was 79.2%. Initiation of bedaquiline rather than delamanid was not associated with treatment success (adjusted odds ratio, .671; 95% confidence interval, .350-1.285). Frequencies of adverse events were not significantly different between the 2 groups. Initial choice of bedaquiline or delamanid did not make any significant difference in the final treatment outcome or the frequencies of adverse events among patients with multidrug-resistant/rifampicin-resistant tuberculosis.

Increasing prevalence of resistance to second-line drugs among multidrug-resistant Mycobacterium tuberculosis isolates in Kuwait

Molecular methods detect genetic mutations associated with drug resistance. This study detected resistance-conferring mutations in gyrA/gyrB for fluoroquinolones and rrs/eis genes for second-line injectable drugs (SLIDs) among multidrug-resistant Mycobacterium tuberculosis (MDR-TB) isolates in Kuwait. Fifty pansusceptible M. tuberculosis and 102 MDR-TB strains were tested. Phenotypic susceptibility testing was performed by MGIT 960 system using SIRE drug kit. GenoType MTBDRsl version 1 (gMTBDRslv1) and GenoType MTBDRsl version 2 (gMTBDRslv2) tests were used for mutation detection. Results were validated by PCR-sequencing of respective genes. Fingerprinting was performed by spoligotyping. No mutations were detected in pansusceptible isolates. gMTBDRslv1 detected gyrA mutations in 12 and rrs mutations in 8 MDR-TB isolates. gMTBDRsl2 additionally detected gyrB mutations in 2 and eis mutation in 1 isolate. Mutations in both gyrA/gyrB and rrs/eis were not detected. gMTBDRslv1 also detected ethambutol resistance-conferring embB mutations in 59 isolates. Although XDR-TB was not detected, frequency of resistance-conferring mutations for fluoroquinolones or SLIDs was significantly higher among isolates collected during 2013–2019 versus 2006–2012. Application of both tests is warranted for proper management of MDR-TB patients in Kuwait as gMTBDRslv2 detected resistance to fluoroquinolones and/or SLIDs in 3 additional isolates while gMTBDRslv1 additionally detected resistance to ethambutol in 58% of MDR-TB isolates.

Assessment of burden of drug-resistant tuberculosis at a tertiary care centre in northern India: a prospective single centre cohort study

ObjectivesWe aim to define the burden of rifampicin monoresistant tuberculosis (TB) at a tertiary care centre in northern India as well as determine the second-line drug susceptibilities (SL-DST) in a...

Performance of the GenoType MTBDRsl V 2.0 for detecting second-line drugs resistance of Mycobacterium tuberculosis isolates in Tunisia

Rapid detection of the second-line drug (SLD) resistant tuberculosis (TB) strains is challenging to prescribe an immediate adequate treatment and limit the transmission of SLD resistant strains.The study aimed to evaluate the performance of GenoType MTBDRsl V2.0 compared to phenotypic drug susceptibility testing (pDST:MGIT960) to detect resistance to SLD of Mycobacterium tuberculosis (MTB) isolates in Tunisia, between May 2015 and December 2019.As a matter of fact, 103 rifampicin-resistant and multidrug-resistant MTB strains were included. Discrepancies between pDST and MTBDRsl were solved by whole genome sequencing.Compared to pDST, MTBDRsl V2.0 showed a sensitivity of 92.8% (68.5%–98.7%) in detecting resistance to fluoroquinolones. As for second-line injectable drugs, it presented a sensitivity of 80.0% (49.0%–94.3%). MTBDRsl had sensitivities of 100.0% (67.5%–100.0%), 75.0% (40.9%–92.8%) and 100.0% (60.9%–100.0%) respectively for kanamycin, capreomycin and amikacin. The specificity was 100.0% for all the drugs evaluated.As for diagnosing XDR-TB, it had a sensitivity of 57.1% (25.0%–84.1%) and a specificity of 100.0% (96.1%–100.0%).MTBDRsl V2.0 showed a high performance in detecting SLD resistance with a short turnaround time compared with pDST, which made it possible to start an early treatment and to maintain a low prevalence of SLD resistance and XDR-TB in Tunisia.

Resistance to Second-Line Anti-TB Drugs in Cambodia: A Phenotypic and Genetic Study

BackgroundDue to the emergence of Mycobacterium tuberculosis (M.tb) clinical isolates resistant to most potent first-line drugs (FLD), second-line drugs (SLD) are being prescribed more frequently. We explore the genetic characteristics and molecular mechanisms of M.tb isolates phenotypically resistant to SLD, including pre-extensively drug-resistant (pre-XDR) and extensively drug-resistant (XDR) isolates.MethodsDrug-resistant (DR) M.tb isolates collected from 2012 to 2017 were tested using sequencing and phenotypic drug susceptibility testing. Genotypes were determined to explore their links with SLD resistance patterns.ResultsOf the 272 DR M.tb isolates, 6 non-multidrug resistant (non-MDR) isolates were fluoroquinolones (FQ)-resistant, 3 were XDR and 16 were pre-XDR (14 resistant to FQ and 2 to second-line injectable drugs). The most frequent mutations in FQ-resistant and second-line injectable drugs resistant isolates were gyrA D94G (15/23) and rrs a1401g (3/5), respectively. Seventy-five percent of pre-XDR isolates and 100% of XDR isolates harbored mutations conferring resistance to pyrazinamide. All XDR isolates belonged to the Beijing genotype, of which one, named XDR+, was resistant to all drugs tested. One cluster including pre-XDR and XDR isolates was observed.ConclusionThis is the first description of SLD resistance in Cambodia. The data suggest that the proportion of XDR and pre-XDR isolates remains low but is on the rise compared to previous reports. The characterization of the XDR+ isolate in a patient who refused treatment underlines the risk of transmission in the population. In addition, genotypic results show, as expected, that the Beijing family is the main involved in pre-XDR and XDR isolates and that the spread of the Beijing pre-XDR strain is capable of evolving into XDR strain. This study strongly indicates the need for rapid interventions in terms of diagnostic and treatment to prevent the spread of the pre-XDR and XDR strains and the emergence of more resistant ones.

Xpert MTB/XDR: a 10-Color Reflex Assay Suitable for Point-of-Care Settings To Detect Isoniazid, Fluoroquinolone, and Second-Line-Injectable-Drug Resistance Directly from Mycobacterium tuberculosis-Positive Sputum.

We describe the design, development, analytical performance, and a limited clinical evaluation of the 10-color Xpert MTB/XDR assay (CE-IVD only, not for sale in the United States). This assay is intended as a reflex test to detect resistance to isoniazid (INH), fluoroquinolones (FLQ), ethionamide (ETH), and second-line injectable drugs (SLIDs) in unprocessed sputum samples and concentrated sputum sediments which are positive for Mycobacterium tuberculosis The Xpert MTB/XDR assay simultaneously amplifies eight genes and promoter regions in M. tuberculosis and analyzes melting temperatures (Tm s) using sloppy molecular beacon (SMB) probes to identify mutations associated with INH, FLQ, ETH, and SLID resistance. Results can be obtained in under 90 min using 10-color GeneXpert modules. The assay can differentiate low- versus high-level resistance to INH and FLQ as well as cross-resistance versus individual resistance to SLIDs by identifying mutation-specific Tm s or Tm patterns generated by the SMB probes. The assay has a limit of detection comparable to that of the Xpert MTB/RIF assay and successfully detected 16 clinically significant mutations in a challenge set of clinical isolate DNA. In a clinical study performed at two sites with 100 sputum and 214 clinical isolates, the assay showed a sensitivity of 94% to 100% and a specificity of 100% for all drugs except for ETH compared to that of sequencing. The sensitivity and specificity were in the same ranges as those of phenotypic drug-susceptibility testing. Used in combination with a primary tuberculosis diagnostic test, this assay should expand the capacity for detection of drug-resistant tuberculosis near the point of care.

Refining MDR-TB treatment regimens for ultra short therapy (TB-TRUST): study protocol for a randomized controlled trial

BackgroundMultidrug-resistant tuberculosis (MDR-TB) are unsatisfied to treat, pressing more effective and innovative treatment regimens. New efficient regimens for MDR-TB have obtained high treatment success rates. However, those regimens without drug susceptibility testing (DST) are also likely to contribute to the emergence of resistance. Precision treatments guided by DST might optimize the patients’ treatment outcome individually and minimize resistance amplification.MethodsTB-TRUST is a phase III, multicenter, open-label, randomized controlled clinical trial of non-inferiority comparing the treatment success rate between the World Health Organization (WHO) shorter regimen and the refined ultra-short regimen for fluoroquinolones and second-line injectable drugs susceptible rifampicin-resistant TB. The control arm uses the WHO injectable-containing shorter regimen for 36–44 weeks depending on time of sputum smear conversion. The investigational arm uses a refined ultra-short regimen guided by molecular DST to pyrazinamide via whole-genome sequencing (WGS) to optimize the treatment of pyrazinamide-susceptible patients with levofloxacin, linezolid, cycloserine and pyrazinamide for 24–32 weeks and pyrazinamide-resistant with levofloxacin, linezolid, cycloserine and clofazimine for 36–44 weeks. The primary outcome is the treatment success rate without relapse at 84 weeks after treatment initiation. Secondary outcomes include the time of sputum culture conversion and occurrence of adverse events. Assuming α = 0.025 level of significance (one-sided test), a power of 80%, a < 10% difference in treatment success rate between control arm and investigational (80% vs. 82%), and a 5% lost follow-up rate, the number of participants per arm to show non-inferiority was calculated as 177(354 in total).DiscussionRapid molecular testing distinguishes patients who are eligible for shorter regimen with fluoroquinolone and the WGS-guided results shorten the treatment to 6 months for pyrazinamide susceptible patients. It’s foreseeable that not only novel developed medicines, but also traditional powerful medicines with the susceptibility confirmed by DST are the key factors to ensure the effect of anti-MDR-TB drugs. As a DST-guided precision treatment, TB-TRUST are expected to optimize therapy outcome in more patients who cannot afford the expensive new medicines and minimize and even avoid resistance amplification with the rational use of anti-TB drugs.Trail registrationClinicalTrial.gov, NCT03867136. Registered on March 7, 2019.

Clinical Interpretation of Drug Susceptibility Tests in Tuberculosis

: Prompt and accurate diagnosis of drug resistance is essential for optimal treatment of drug-resistant tuberculosis. However, only 20% of the more than half a million patients eligible for the treatment of MDR-TB/RR-TB receive an appropriate drug regimen. Drug-resistant TB regimens must include a sufficient number of effective medications, a significant challenge for clinicians worldwide, as most are forced to make therapeutic decisions without any, or very little information on drug susceptibility testing. Although phenotypic DST is still commonly regarded as the gold standard for determining M. tuberculosis susceptibility to antituberculosis drugs, it has several limitations, mainly its prolonged turnaround time. Molecular methods based on M. tuberculosis genomic DNA sequencing have been developed during the past two decades, to identify the most common mutations involved in drug resistance. The Xpert ® MTB/RIF is a real-time polymerase chain reaction that offers results in less than two hours and has an overall sensitivity for rifampin resistance of 96% and 98% specificity. Line probe assays (LPAs) are commercial DNA strip-based tests for detecting the most frequent mutations responsible for resistance to rifampin, isoniazid, fluoroquinolones, and second-line injectable drugs. : Discrepancies between phenotypic and genotyping methods are a problem that the clinician will face in everyday practice. However, any resistance result (with any type of test) in a person with risk factors for harboring resistant microorganisms should be considered appropriate while the results of complementary tests are available.

Targeted next generation sequencing directly from sputum for comprehensive genetic information on drug resistant Mycobacterium tuberculosis

BackgroundTimely drug resistance detection is essential to global tuberculosis management. Unfortunately, rapid molecular tests assess resistance to only a few drugs, with culture required for comprehensive susceptibility test results. MethodsWe evaluated targeted next generation sequencing (tNGS) for tuberculosis on 40 uncultured sputum samples. Resistance profiles from tNGS were compared with profiles from Xpert MTB/RIF, line probe assay (LPA), pyrosequencing (PSQ), and phenotypic testing. Concordance, sensitivity, specificity, and overall test agreement were compared across assays. ResultstNGS provided results for 39 of 40 samples (97.5%) with faster turnaround than phenotypic testing (median 3 vs. 21 days, p = 0.0068). Most samples were isoniazid and rifampin resistant (N = 31, 79.5%), 21 (53.8%) were fluoroquinolone resistant, and 3 (7.7%) were also resistant to Kanamycin. Half were of the Beijing lineage (N = 20, 51.3%). tNGS from uncultured sputum identified all resistance to isoniazid, rifampin, fluoroquinolones, and second-line injectable drugs that was identified by other methods. Agreement between tNGS and existing assays was excellent for isoniazid, rifampin, and SLDs, very good for levofloxacin, and good for moxifloxacin. ConclusiontNGS can rapidly identify tuberculosis, lineage, and drug resistance with faster turnaround than phenotypic testing. tNGS is a potential alternative to phenotypic testing in high-burden settings.

Discordance between Genexpert, Line Probe Assay and Drug Susceptibility Test in Assessing Drug-Resistant Tuberculosis

Background: Rapid molecular diagnostics have potentially revolutionized early detection of drug-resistanttuberculosis (DR-TB) in Indonesia. However, there is discordance between conventional culture usingdrug susceptibility test (DST) and rapid diagnostic tools using GeneXpert and line probe assay (LPA).This discordance result can cause confusion to clinician in determining diagnosis of DR-TB. Objective:This study aimed to identify discordance between GeneXpert, LPA, and DST. Methods: A retrospectivestudy was conducted at Dr. Soetomo General Academic Hospital, Surabaya, Indonesia. Data were collectedbased on medical record between third to fourth quarter of 2018. Rifampicin resistant-tuberculosis (RR-TB)proven by GeneXpert, were further analyzed with second-line LPA and DST. Discordance result betweenit was analyzed using McNemar. Results: Among 81 patients diagnosed with DR-TB, 59 patients RR-TBwere eligible in this study. There were 13 (22.0%) DST rifampicin result showed sensitive but resistantto GeneXpert. Among 53 samples from LPA, there were 3 (5.7%) result showed LPA fluoroquinoloneresistant but sensitive to DST ofloxacin; 10 (18.9%) result has LPA fluoroquinolone sensitive but resistantto DST ofloxacin; 2 (3.8%) has LPA second-line injectable drug (LPA SLID) resistant but sensitive to DSTkanamycin; 5(9.4%) has LPA SLID sensitive but resistant to DST kanamycin. The McNemar analysis showeddiscordance between GeneXpert and DST rifampicin was 13 (22.0%; p=0.046); LPA fluoroquinolone andDST ofloxacin was 13 (24.6%; p=0.042); LPA SLID and DST kanamycin was 7 (13.2%; p=0.183). Novariable that can be used to analyze discordance result between GeneXpert and LPA. Conclusion: Thereis significant discordance between GeneXpert and DST; LPA fluoroquinolone and DST ofloxacin, whileneither LPA SLID nor DST kanamycin shows no significant discordance.

Impact of Bedaquiline on Multidrug-Resistant Tuberculosis Treatment to Mother and Baby: An Incidental Case

Background: Bedaquiline is a new drug which is recommended by World Health Organization (WHO) forindividual regiment drug resistant-tuberculosis (DR-TB). The presence of regiment DR-TB in the bloodis long enough with T1/2 5-6 months, that is why bedaquiline is given on six months. Bedaquiline is notrecommended for pregnant women because there is no data related to safety. The author will report anincidental pregnant female on bedaquiline treatment.Case presentation: A 24-year-old woman with multidrug resistant tuberculosis (MDR TB) on individualregiment bedaquiline had incidental pregnancy at the 6th month treatment. In the beginning, the patientused bedaquiline because of the intolerance of second-line injectable drug. Bedaquiline regiment was usedfor 24th week. Pregnancy occured at the 6th month treatment. The patient continued the pregnancy and theMDR TB treatment was continued without bedaquiline. Nausea and vomiting were getting worse. Pretermlabour occured in 33/34 weeks by cesarean section. The baby had severe asphyxia, used continuous positiveairway pressure (CPAP), treated in NICU, had low weight but there was no disability. After several days oftreatment, the condition of baby was improving and was able to outpatient.Conclusion: The preterm labour, low birth weight, and neonatal emergency occured in a pregnant womanwith MDR TB on individual regiment bedaquiline. Mother and baby can survive. More case and researchdata are needed on the safety of bedaquiline during pregnancy.

Assessment of line probe assay for rapid detection of extensively drug-resistant Mycobacterium tuberculosis isolates

Aims and objectives: Molecular techniques have considerable advantages for rapid detection, a reduction of infectiousness, prevention of further resistance development and surveillance of drug-resistant TB. MTBDRsl VER 2.0 was used to detect resistance to second-line anti-tuberculosis drugs on rifampicin-resistant M. tuberculosis (RR-MTB) isolates compared to the minimum inhibitory concentrations (MICs) and whole genome sequencing (WGS). Methods: The MTBDRsl VER 2.0 (Hain Life Science, Nehren, Germany) and WGS (San Diego, CA, USA) was performed for tracing mutations in resistant-related genes involved in resistance to fluoroquinolone (FLQs) and second-line injectable drugs (SLIDs). The broth microdilution method using 7H9 Middlebrook media supplemented with OADC was used to determine the MICs. Results: The MTBDRsl VER 2.0 correctly detected 5/6 (83.3%) of FLQ-resistant strains having gyrA mutations. The MUT1 A1401G (7 strains) and MUT2 G1484T (1 strain) mutations in rrs gene were detected in 8 AMK/KAN/CAP-resistant strains. Four low-level KAN-resistant strains with the G-10A/C-12T (3 strains) and C-14T (1 strain) mutations in eis gene was diagnosed using MTBDRsl VER 2.0. Conclusions: Five error results were found in detecting resistance to kanamycin and capreomycin compared to the phenotypic drug susceptibility testing and WGS. Failing wild type-bands without improved mutant-bands did not indicate a reliable resistance. WGS could efficiently resolve the discrepancies of the results. MTBDRsl showed better performance in detecting extensively drug-resistant strains.

A systemic approach to explore the mechanisms of drug resistance and altered signaling cascades in extensively drug-resistant tuberculosis.

The persistence of extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis (MTB) continue to pose a significant challenge to the treatment and control of tuberculosis infections worldwide. XDR-MTB strains exhibit resistance against first-line anti-TB drugs, fluoroquinolones, and second-line injectable drugs. The mechanisms of drug resistance of MTB remains poorly understood. Our study aims at identifying the differentially expressed genes (DEGs), associated gene networks, and signaling cascades involved in rendering this pathogen resistant to multiple drugs, namely, isoniazid, rifampicin, and capreomycin. We used the microarray dataset GSE53843. The GEO2R tool was used to prioritize the most significant DEGs (top 250) of each drug exposure sample between XDR strains and non-resistant strains. The validation of the 250 DEGs was performed using volcano plots. Protein-protein interaction networks of the DEGs were created using STRING and Cytoscape tools, which helped decipher the relationship between these genes. The significant DEGs were functionally annotated using DAVID and ClueGO. The concomitant biological processes (BP) and molecular functions (MF) were represented as dot plots. We identified relevant molecular pathways and biological processes, such as cell wall biogenesis, lipid metabolic process, ion transport, phosphopantetheine binding, and triglyceride lipase activity. These processes indicated the involvement of multiple interconnected mechanisms in drug resistance. Our study highlighted the impact of cell wall permeability, with the dysregulation of the mur family of proteins, as essential factors in the inference of resistance. Additionally, upregulation of genes responsible for ion transport such as ctpF, arsC, and nark3, emphasizes the importance of transport channels and efflux pumps in potentially driving out stress-inducing compounds. This study investigated the upregulation of the Lip family of proteins, which play a crucial role in triglyceride lipase activity. Thereby illuminating the potential role of drug-induced dormancy and subsequent resistance in the mycobacterial strains. Multiple mechanisms such as carboxylic acid metabolic process, NAD biosynthetic process, triglyceride lipase activity, phosphopantetheine binding, organic acid biosynthetic process, and growth of symbiont in host cell were observed to partake in resistance of XDR-MTB. This study ultimately provides a platform for important mapping targets for potential therapeutics against XDR-MTB.