Second-line Injectable Drugs Research Articles

Evaluation of extracts from used Xpert MTB/RIF cartridges for detection of resistance to second-line anti-tuberculosis drugs in patients with multidrug-resistant tuberculosis in Ethiopia

BackgroundEarly and accurate diagnosis of drug resistance, including resistance to second-line anti-tuberculosis (TB) drugs, is crucial for the effective control and management of pre-extensively drug-resistant TB (pre-XDR-TB) and extensively drug-resistant TB (XDR-TB). The Xpert MTB/XDR assay is the WHO recommended method for detecting resistance to isoniazid and second-line anti-TB drugs when rifampicin resistance is detected. Currently, the Xpert MTB/XDR assay is not yet implemented in Ethiopia, thus the MTBDRsl assay continues to be used. However, the MTBDRsl assay requires additional patient visits and specimen collection, which can lead to delays in diagnosis and treatment initiation.ObjectiveThis study aimed to evaluate the feasibility of using extracts from used Xpert MTB/RIF cartridges for detecting resistance to second-line anti-TB drugs by MTBDRsl assay in patients with rifampicin resistant-TB (RR-TB) in Eastern and Western Oromia, Ethiopia.MethodsA cross-sectional diagnostic evaluation study was conducted from June 2020 to May 2021 at two TB Referral Laboratories in Eastern and Western Oromia, Ethiopia. Sputum samples from RR-TB patients were split, with one aliquot being subjected for Xpert testing and the other being cultured on Lowenstein-Jensen media. DNA extracted from the used Xpert cartridges was amplified by PCR and tested by MTBDRsl assay, and the results were compared to those obtained from culture isolates. To establish the detection limits, the MTBDRsl assay was performed on cartridge extracts (CEs) from a series of dilutions of drug-susceptible and multidrug-resistant TB strains.ResultsThe MTBDRsl on CEs from dilutions at ≥ 102 CFU/mL (CT ≤ 22) accurately identified susceptibility and resistance patterns for fluoroquinolones (FQL) and second-line injectable drugs (SLIDs). The MTBDRsl on rifampicin-resistant CEs from sputum samples (n = 40) yielded 100% interpretable results for FQL and 90% (4 indeterminate) interpretable results for SLIDs. All interpretable CE results showed complete agreement with the MTBDRsl results from the culture isolates.ConclusionThis study demonstrated the feasibility of using extracts from used Xpert MTB/RIF cartridges for detecting resistance to second-line anti-TB drugs using the MTBDRsl assay. This approach could mitigate the need for additional specimen collection and allow for earlier treatment initiation, potentially improving patient outcomes and reducing the transmission of drug-resistant TB strains.

Xpert MTB/XDR assay: rapid TB drug resistance detection.

To assess the Xpert MTB/XDR assay's efficiency in promptly detecting resistance to isoniazid, fluoroquinolones, ethionamide, and second-line injectable drugs among tuberculosis (TB) patients. From August 2020 to July 2021, TB suspected patient samples were enrolled at a tertiary care center for our study. We conducted mycobacterial culture, phenotypic DST using proportion method in liquid culture at WHO-recommended concentrations, and the line probe assay (LPA). Simultaneously, the Index test, Xpert MTB/XDR, was performed following the manufacturer's instructions. Among 360 samples, 107 were excluded due to incomplete information. Resistance to isoniazid, levofloxacin and moxifloxacin was found in 45/251, 21/251 and 20/251 samples, respectively by phenotypic DST. The diagnostic accuracy of Index test, taking phenotypic DST as a reference standard, was 95.8%, 99.04%, and 99.05% for isoniazid, levofloxacin, and moxifloxacin, respectively. The Index test assay demonstrated a specificity of 99.1% for detecting SLID resistance, yielding a diagnostic accuracy of 99.2. Comparing the Index test with LPA revealed a significant enhancement in sensitivity for detecting isoniazid resistance (86.7% vs. 82.2%). The Index test exhibited promising outcomes in identifying resistance to isoniazid and fluoroquinolones, surpassing the performance of the LPA. This could be valuable for promptly initiating treatment in cases of drug-resistant tuberculosis.

GENOMIC CHARACTERIZATION AND DRUG RESISTANCE PROFILES OF MYCOBACTERIUM TUBERCULOSIS LINEAGE 2 IN KAZAKHSTAN: PRELIMINARY RESULTS

Tuberculosis remains a highly contagious infection, with an estimated annual transmission of about 10 million people globally, as reported in the latest Global Tuberculosis Report by the World Health Organization (WHO). The primary objective of this research is to determine the geographical distribution and drug resistance profiles of Mycobacterium tuberculosis lineage 2, which is predominant in Kazakhstan. A total of over 200 clinical isolates of M. tuberculosis complex (MTBC) were collected from regional phthisiopulmonology centers across all regions of Kazakhstan between 2012 and 2024. Clinical isolates were genotyped using a PCR assay targeting the dnaA-dnaN:IS6110 region, specific for the modern Beijing genotype. Subsequently, selected samples were sequenced using the Illumina MiSeq platform. The TB-Profiler prediction tool was utilized to identify resistance against anti-tubercular drugs and to genotype the lineages. A total of 102 clinical isolates belonging to the L2 modern Beijing genotype were selected for whole-genome sequencing (WGS). The L2.2.1 genetic cluster was identified as the only sublineage present, according to Coll et al.'s classification. More than half of the specimens were found to be multidrug-resistant (n=60, 59%). Among the analyzed samples, monoresistance to isoniazid (IHN) was detected in 17 (16%) cases, while 14 (14%) cases were drug-susceptible TB. Additionally, 7 (7%) cases were identified as Pre-XDR (resistant to rifampicin, isoniazid, and either fluoroquinolones or second-line injectable drugs), 3 (3%) cases were monoresistant to streptomycin, and 1 (1%) case exhibited resistance to rifampicin only. Regional distribution of samples is as follows: Aktau and Kostanay are 14% (n=13/102), Kyzylorda (n=12/102), Taldykourgan (n=11/102), Pavlodar, Karaganda, and Atyrau are at 6% (6/102); Semey is 10% (n=9/102), Almaty and Taraz at 4%, and Shymkent city is 1% (n=1/102). This ongoing research is focused on resistance patterns, genotypes, and transmission dynamics among different regions of Kazakhstan using next-generation sequencing, followed by bioinformatics analysis and interpretation of the data.

Performance evaluation of the Xpert MTB/XDR test for the detection of drug resistance to Mycobacterium tuberculosis among people diagnosed with tuberculosis in South Africa.

Drug-resistant tuberculosis (TB) poses a significant public health concern in South Africa due to its complexity in diagnosis, treatment, and management. This study assessed the diagnostic performance of the Xpert MTB/XDR test for detecting drug resistance in patients with TB by using archived sputum sediments. This study analyzed 322 samples collected from patients diagnosed with TB between 2016 and 2019 across South Africa, previously characterized by phenotypic and genotypic methods. The Xpert MTB/XDR test was evaluated for its ability to detect resistance to isoniazid (INH), ethionamide (ETH), fluoroquinolones (FLQ), and second-line injectable drugs (SLIDs) compared with phenotypic drug susceptibility testing (pDST) and whole-genome sequencing (WGS). Culture, Xpert MTB/RIF Ultra, and Xpert MTB/RIF (G4) tests were performed to determine sensitivity and agreement with this test for TB detection. The sensitivities using a composite reference standard, pDST, and sequencing were >90% for INH, FLQ, amikacin (AMK), kanamycin (KAN), and capreomycin (CAP) resistance, meeting the WHO target product profile criteria for this class. A lower sensitivity of 65.9% (95% CI: 57.1-73.6) for ETH resistance was observed. The Xpert MTB/XDR showed a sensitivity of 98.3% (95% CI: 96.1-99.3) and specificity of 100% (95% CI: 86.7-100) compared with culture, a positive percent agreement (PPA) of 98.8% (95% CI: 93.7-99.8) and negative percent agreement (NPA) of 100.0% (95% CI: 78.5-100.0) compared with G4, and a PPA of 99.5% (95% CI: 97.3-99.9) and NPA of 100.0% (95% CI: 78.5-100.0) compared with Xpert MTB/RIF Ultra for detecting Mycobacterium tuberculosis. The test offers a promising solution for the rapid detection of drug-resistant TB and could significantly enhance control efforts in this setting.

Diagnostic accuracy of the Xpert® MTB/XDR assay for detection of Isoniazid and second-line antituberculosis drugs resistance at central TB reference laboratory in Tanzania

IntroductionEarly diagnosis of tuberculosis (TB) and universal access to drug-susceptibility testing (DST) are critical elements of the WHO End TB Strategy. Current rapid tests (e.g., Xpert® MTB/RIF and Ultra-assays) can detect rifampicin resistance-conferring mutations, but cannot detect resistance to Isoniazid and second-line anti-TB agents. Although Line Probe Assay is capable of detecting resistance to second-line anti-TB agents, it requires sophisticated laboratory infrastructure and advanced skills which are often not readily available in settings replete with TB. A rapid test capable of detecting Isoniazid and second-line anti-TB drug resistance is highly needed.MethodsWe conducted a diagnostic accuracy study to evaluate a new automated Xpert MTB/XDR 10-colour assay for rapid detection of Isoniazid and second-line drugs, including ethionamide, fluoroquinolones, and injectable drugs (Amikacin, Kanamycin, and Capreomycin). Positive Xpert MTB/RIF respiratory specimens were prospectively collected through routine diagnosis and surveillance of drug resistance at the Central TB Reference Laboratory in Tanzania. Specimens were tested by both Xpert XDR assay and LPA against culture-based phenotypic DST as the reference standard.FindingsWe analysed specimens from 151 TB patients with a mean age (SD) of 36.2 (12.7) years. The majority (n = 109, 72.2%) were males. The sensitivity for Xpert MTB/XDR was 93.5% (95% CI, 87.4–96.7); for Isoniazid, 96.6 (95% CI, 92.1–98.6); for Fluoroquinolone, 98.7% (95% Cl 94.8–99.7); for Amikacin, 96.6%; and (95% CI 92.1–98.6) for Ethionamide. Ethionamide had the lowest specificity of 50% and the highest was 100% for Fluoroquinolone. The diagnostic performance was generally comparable to that of LPA with slight variations between the two assays. The non-determinate rate (i.e., invalid M. tuberculosis complex detection) of Xpert MTB/XDR was 2·96%.ConclusionThe Xpert MTB/XDR demonstrated high sensitivity and specificity for detecting resistance to Isoniazid, Fluoroquinolones, and injectable agents. This assay can be used in clinical settings to facilitate rapid diagnosis of mono-isoniazid and extensively drug-resistant TB.

Proficiency of phenotypic drug susceptibility testing for Mycobacterium tuberculosis in China, 2008-2021.

To analyze the results of proficiency testing for anti-tuberculosis drug susceptibility testing (DST) in China. Number of laboratory participating the proficiency testing performed DST, and the sensitivity, specificity, reproducibility, and accordance rate were calculated from data of 13 rounds proficiency testing results for DST from 2008 to 2021. A total of 30 and 20 strains of Mycobacterium tuberculosis with known susceptibility results were sent to each laboratory in 2008 to 2019, 2020 and 2021, respectively. The number of participating laboratories ranged from 30 in 2009 to 546 in 2021. L-J DST was the predominant method. The specificity presented relatively higher than sensitivity. Improvement of specificity were observed for all drugs through the years, while sensitivity did not show improvement for amikacin and capreomycin. Accordance rate of pyrazinamide and kanamycin and reproducibility of capreomycin and pyrazinamide were not significantly improved through the years. Most of the participating laboratories significantly improved the quality of their DST through the consecutive rounds of proficiency testing except for second-line injectable drugs and pyrazinamide. The results highlight the importance of developing novel and/or improving existing methods for phenotypic DST for certain drugs.

Assessing the safety of bedaquiline: insight from adverse event reporting system analysis.

The development and marketing of Bedaquiline (BDQ) represent significant advancements in treating tuberculosis, particularly multidrug-resistant forms. However, comprehensive research into BDQ's real-world safety remains limited. We obtained BDQ related adverse event (AE) information from the US Food and Drug Administration's Adverse Event Reporting System (FAERS) to assess its safety and inform drug usage. The AE data for BDQ from 2012 Q4 to 2023 Q3 was collected and standardized. Disproportionality analysis, including Reporting Odds Ratio (ROR), Proportional Reporting Ratio (PRR), Multi-item Gamma Poisson Shrinker (MGPS), and Bayesian Confidence Propagation Neural Network (BCPNN) was used to quantify signals of BDQ-related AEs. Logistic regression was used to analyze the individual data of hepatotoxicity and drug-induced liver injury, and multiple linear regression models were established. Additionally, network pharmacology was employed to identify the potential biological mechanisms of BDQ-induced liver injury. We identified 2017 case reports directly related to BDQ. Our analysis identified 341 Preferred Terms (PTs) characterizing these AEs across 27 System Organ Classes (SOC). An important discovery was the identification of AEs associated with ear and labyrinth disorders, which had not been documented in the drug's official leaflet before. Subgroup analysis revealed a negative correlation between BDQ-related liver injury and females (OR: 0.4, 95%CI: 0.3-0.6). In addition, via network pharmacology approach, a total of 76 potential targets for BDQ related liver injury were predicted, and 11 core target genes were selected based on the characterization of protein-protein interactions. The pathway linked to BDQ-induced liver injury was identified, and it was determined that the PI3K-Akt signaling pathway contained the highest number of associated genes. The analysis of the FAERS database revealed adverse events linked to BDQ, prompting the use of a network pharmacology approach to study the potential molecular mechanism of BDQ-induced liver injury. These findings emphasized the significance of drug safety and offered understanding into the mechanisms behind BDQ-induced liver injury. BDQ demonstrated distinct advantages, including reduced incidence of certain adverse events compared to traditional treatments such as injectable agents and second-line drugs. However, it is important to acknowledge the limitations of this analysis, including potential underreporting and confounding factors. This study provides valuable insights into the safety of BDQ and its role in the management of MDR-TB, emphasizing the need for continued surveillance and monitoring to ensure its safe and effective use.

Evaluation of MeltPro Assay in Identification of Second-Line Injectable Drug Resistance in Multidrug-Resistant Tuberculosis Isolates.

We compared the MeltPro assay to whole-genome sequencing (WGS) to investigate the molecular characterization of second-line injectable drug (SLID) resistance in multidrug-resistant tuberculosis (MDR-TB) isolates in Chongqing, China. A total of 122 MDR-TB patient isolates were collected between March 2019 and June 2020 from Chongqing Municipality, China. Conventional drug-susceptibility testing was performed using the proportion method, followed to generate minimum inhibitory concentrations (MICs) of SLIDs determined by microplate alamarblue assay. All strains were subjected to both MeltPro and WGS assays. Among 122 MDR-TB isolates, 30 (24.6%), 22 (18.0%), and 14 (11.5%) were resistant to kanamycin (KM), amikacin (AM), and capreomycin (CM), respectively. Of the 31 SLID-resistant isolates, 24 (77.4%, 24/31) isolates harbored mutations in the rrs gene, with the most prevalent mutations in rrs A1401G (22/24, 91.7%). Mutation in rrs A1401G was associated with high levels of resistance to KM (MIC, ≥40 μg/mL) and AM (MIC, ≥64 μg/mL), but disparities in CM-resistance levels. Using phenotypic drug-susceptibility testing as gold standard, we found that the overall sensitivity of MeltPro and WGS was 87.1% and 90.32% and specificity 100% and 97.8%, respectively. Seven isolates had discordant results between phenotypic and genotypic resistance of SLIDs. MeltPro is a promising diagnostic tool for accurate identification of SLID-resistant MTB isolates with mutations in the rrs and eis genes. There was a disparity between MeltPro with WGS results in the proportion of heterogeneous drug-resistant bacteria with rrs mutation and limited probes. Resistance mechanisms other than genetic mutations will affect the consistency of MeltPro and WGS with phenotypic drug-susceptibility results.

Patterns and profiles of drug resistance-conferring mutations in Mycobacterium tuberculosis genotypes isolated from tuberculosis-suspected attendees of spiritual holy water sites in Northwest Ethiopia.

This study examined the patterns and frequency of genetic changes responsible for resistance to first-line (rifampicin and isoniazid), fluoroquinolones, and second-line injectable drugs in drug-resistant Mycobacterium tuberculosis (MTB) isolated from culture-positive pulmonary tuberculosis (PTB) symptomatic attendees of spiritual holy water sites (HWSs) in the Amhara region. From June 2019 to March 2020, a cross-sectional study was carried out. A total of 122 culture-positive MTB isolates from PTB-suspected attendees of HWSs in the Amhara region were evaluated for their drug resistance profiles, and characterized gene mutations conferring resistance to rifampicin (RIF), isoniazid (INH), fluoroquinolones (FLQs), and second-line injectable drugs (SLIDs) using GenoType®MTBDRplus VER2.0 and GenoType®MTBDRsl VER2.0. Drug-resistant MTB isolates were Spoligotyped following the manufacturer's protocol. Genetic changes (mutations) responsible for resistance to RIF, INH, and FLQs were identified in 15/122 (12.3%), 20/122 (16.4%), and 5/20 (25%) of MTB isolates, respectively. In RIF-resistant, rpoB/Ser531Lue (n = 12, 80%) was most frequent followed by His526Tyr (6.7%). Amongst INH-resistant isolates, katG/Ser315Thr1 (n = 19, 95%) was the most frequent. Of 15 MDR-TB, the majority (n = 12, 80%) isolates had mutations at both rpoB/Ser531Leu and katG/Ser315Thr1. All 20 INH and/or RIF-resistant isolates were tested with the MTBDRsl VER 2.0, yielding 5 FLQs-resistant isolates with gene mutations at rpoB/Ser531Lue, katG/Ser315Thr1, and gyrA/Asp94Ala genes. Of 20 Spoligotyped drug-resistant MTB isolates, the majority (n = 11, 55%) and 6 (30%) were SIT149/T3-ETH and SIT21/CAS1-Kili sublineages, respectively; and they were any INH-resistant (mono-hetero/multi-). Of 15 RIF-resistant (RR/MDR-TB) isolates, 7 were SIT149/T3-ETH, while 6 were SIT21/CAS1-Kili sublineages. FLQ resistance was detected in four SIT21/CAS1-Kili lineages. In the current study, the most common gene mutations responsible for resistance to INH, RIF, and FLQs were identified. SIT149/T3-ETH and SIT21/CAS1-Kili constitute the majority of drug-resistant TB (DR-TB) isolates. To further understand the complete spectrum of genetic changes/mutations and related genotypes, a sequencing technology is warranted.

Targeted genome sequencing for tuberculosis drug susceptibility testing in South Africa: a proposed diagnostic pipeline.

In July 2023, the World Health Organization (WHO) began recommending targeted next-generation sequencing (tNGS), due to its ability to detect resistance to many drugs with a single test. In March 2023, South Africa further adopted the GeneXpert XDR cartridge, which detects mutations associated with resistance to second-line injectable drugs. Here, we consider the feasibility for implementing tNGS in South Africa, what such a facility might look like and the specific context of this upper-middle-income country. Whilst the WHO now recommends tNGS for TB diagnostics and DST, there are many economic and infrastructural challenges opposing its deployment. In lieu of this, we instead recommend a stratified diagnostic pipeline that utilizes South Africa's existing GeneXpert technologies, attempting to reduce the costs associated with implementation of tNGS.

P27 A challenging case of MDR TB infection following a holiday in India

Abstract Background TB is an infection caused by Mycobacterium tuberculosis. MDR TB is caused by strains of M. tuberculosis resistant to isoniazid and rifampicin.1 XDR TB refers to strains resistant to one or more second-line injectable drugs and any fluoroquinolone, whereas pre-XDR TB refers to strains resistant to either a second-line injectable drug or a fluoroquinolone.1 The implications of MDR TB include prolonged treatment requirements, increased morbidity and mortality, and risk of onward transmission to others.2 Case history A woman in her forties with poorly controlled diabetes was admitted to hospital three times in 3 months with respiratory symptoms and pulmonary consolidation. She was treated for recurrent community acquired pneumonia (CAP). On her fourth admission, sputum and stool microscopy detected acid fast bacilli (AFB) and PCR using Xpert MTB/RIF (Cepheid® GeneXpert® systems) confirmed M. tuberculosis with resistance to rifampicin. She had no known TB contacts but had had a 5 week holiday in Goa, India, 2 years prior. Management Phenotypic testing confirmed the M. tuberculosis isolate was resistant to rifampicin, isoniazid and aminoglycosides but susceptible to fluoroquinolones. Following discussion with the British Thoracic Society (BTS) MDR TB advice service she was empirically initiated on linezolid 600 mg BD, bedaquiline 200 mg OD, levofloxacin 1000 mg OD, clofazimine 200 mg OD, cycloserine 250 mg BD, pyrazinamide 2000mg OD, ethambutol 1000 mg OD and pyridoxine 10 mg OD. The isolate was later identified as of New Delhi Central Asia lineage, with additional resistance to pyrazinamide (which was then stopped). This is the first case of this lineage reported in the UK. Therapeutic drug monitoring of linezolid, levofloxacin and cycloserine was performed. Cycloserine was changed to terizidone 250 mg BD after 1 month, due to a national supply issue. She suffered from medication side effects including diarrhoea, nausea, derangement in liver functions tests, worsening of pre-existing peripheral neuropathy, myalgia, hypercalcaemia, itch, renal tubular acidosis and acute kidney injury. These were managed pharmacologically and through cessation of terizidone after 2 months and dose reduction, then cessation, of linezolid after 4 months. Outcomes Clinically she improved and repeat imaging showed gradual resolution of consolidation and C-reactive protein levels decreased. She is 10 months into an anticipated 18–24 month treatment regimen, recommended due to her extensive pulmonary disease. Medication side effects are currently well controlled. The infection prevention and control team screened all contacts from this and prior admissions, with no further cases identified. Conclusions This case highlights the importance of suspicion of TB in patients with chronic cough and radiological changes, particularly with risk factors for TB such as relevant travel history and diabetes. MDR TB infection has significant consequences and treatment remains challenging with the burden of multiple drugs, and their side effects, leading to further patient morbidity.

Pre-extensively drug-resistant tuberculosis among pulmonary multidrug-resistant tuberculosis patients in Eastern Nigeria.

Pre-extensively drug-resistant tuberculosis (Pre-XDR-TB), an emerging form of drug-resistant tuberculosis, is challenging efforts at tuberculosis control, leading to treatment failure among multidrug-resistant tuberculosis (MDR-TB) patients and progression to extensively drug-resistant tuberculosis (XDR-TB). We determined the rate of Pre-XDR-TB among multidrug-resistant patients in Southeast, Nigeria. A prospective laboratory-based study was carried out at the South East Zonal Tuberculosis Reference Laboratory from January 2021 to December 2021. Second-line drug (SLD) resistance was performed on 225 sputum samples of multidrug-resistant patients prior to treatment initiation using GenoType MTBDRsl genotypic drug susceptibility testing (DST) method. The rate of Pre-XDR-TB among 225 MDR-TB cases was 3.1%. Fluoroquinolone-resistant Pre-XDR-TB was observed (100%) in previously treated tuberculosis cases. Only one (0.4%) case showed resistance to both fluoroquinolone (FQ) and one second-line injectable drug (XDR-TB). The extensively drug-resistant case observed was a de-novo resistance. Exactly 0.9% of the multidrug-resistant cases showed resistance to second-line injectables. The prevalence of Pre-XDR-TB among MDR-TB cases was high. There is need for rapid detection of Pre-XDR-TB among MDR-TB cases before treatment initiation.

Characterization of mutations conferring streptomycin resistance in \(\textit{Mycobacterium tuberculosis}\) in Vietnam

Recently, World Health Organization (WHO) has listed streptomycin (STR) in the list of second-line injectable drugs in the multidrug-resistant tuberculosis (MDR-TB) regimens and may replace amikacin under the same conditions. Nevertheless, molecular characterizations associated with STR resistance in the Mycobacterium tuberculosis population have not been fully investigated in Vietnam. The present study aimed to explore the variation and frequency of mutations in rpsL and rrs genes and their relationship with drug-resistant patterns and M. tuberculosis genotypes in 163 STR-resistant strains from Vietnam. The mutation frequency of the rpsL and rrs genes were 62% and 20.9%, respectively, and the mutation combination in both genes covered 81% of STR-resistant strains. The most prevalent mutations included rpsL Lys43Arg (38.7%), Lys88Arg (19.6%), rrs A514C (10.4%) and A517C (5.5%). Thus, sequence analysis of rpsL and rrs exhibited a sensitivity of 81% and specificity of 100% for the prediction of STR resistance in Vietnamese M. tuberculosis strains. The prevalence of STR-resistant mutations in double, triple and quadruple resistance strains was significantly different, compared with mono STR-resistant ones. Similarly, mutation frequency associated with STR resistance in MDR strains was significantly higher than that in non-MDR strains. In addition, the lineage 2 genotype was significantly correlated with a high rate of STR resistance-conferring mutation, as well as the mutation rpsL Lys43Arg (P < 0.01), while the lineage 1 genotype was associated with a low rate of STR resistance-conferring mutation and rrs mutations (P<0.05). In conclusion, sequence analysis may be useful for the rapid detection of STR resistance in MDR M. tuberculosis strains, which in turn could contribute to better control strategies of TB in Vietnam. Other molecular mechanisms associated with STR resistance in STR-resistant strains without mutations in the rpsL and rrs genes need to be further investigated.

Incidence and Patterns of Drug Resistance in Patients with Spinal Tuberculosis: a Prospective, Single-Center Study from a Tuberculosis-Endemic Country.

There is paucity of data on incidence and pattern of drug resistance in spinal TB. This prospective observational study was conducted to document the incidence and drug-resistance pattern among primary and presumptive resistant cases. 59 consecutive cases diagnosed clinico-radiologically (imaging) were grouped into Group A (n = 51, primary cases) and Group B (n = 8, presumptive resistant cases) based on pre-defined criteria (INDEX-TB guidelines). Tissue samples obtained percutaneously (37.29%, 22/59) and on surgery (62.71%, 37/59) were subjected to genotypic DST (CBNAAT, LPA) and phenotypic DST (BACTEC MGIT 960 culture and sensitivity using fixed critical concentration of drugs). Etiological diagnosis was ascertained in all. 13/51 (25.49%) in Group A, while 3/8 (37.5%) in Group B and 16/59 (27.12%) overall demonstrated drug resistance. 12/16 (75%) had no prior history of ATT intake. 4 demonstrated INH (Isoniazid) mono-resistance. 12 polydrug resistance demonstrated: 5MDR, 3pre-XDR, while RIF + FQ (fluoroquinolones), FQ + Lz (linezolid), only SLID (second-line injectable drugs), and only FQ resistance observed in 1 case each. Isolated RIF (Rifampicin) resistance and XDR pattern were not observed. Overall frequency of RIF resistance was 16.4% (9/55) and INH was 25% (12/48) with low-(n-2) and high-level INH resistance (n-10). Among second-line drugs, FQ resistance was more than SLID resistance and within FQ, levofloxacin resistance was more frequent than moxifloxacin. MGIT demonstrated positive growth in 16/59 samples, out of which 1 sample was positive for nontuberculous mycobacteria (M. chelonae) but on genotypic testing demonstrated MTB resistant to RIF and FQ. This is the first report on incidence and drug-resistant pattern in culture-positive/negative cases. High (25.49%) primary drug resistance is worrisome. This being the first study in spinal TB cases which document prevalent drug-resistant pattern as evaluated for consecutive culture-positive/negative cases. The tissue obtained must be submitted for AFB culture and molecular tests to ascertain drug resistance in culture-positive/negative cases. However, in the presence of insufficient tissue sample histology and CBNAAT can ascertain etiological diagnosis in 100% cases. INH resistance is more than RIF with isolated RIF resistance unreported.

Drug Resistant Tuberculosis: A Major Risk to Global Health Security Treatment

The continuing spread of drug-resistant tuberculosis (TB) is one of the most urgent and difficult challenges facing global TB control. Patients who are infected with strains resistant to isoniazid and rifampicin, called multidrug-resistant (MDR) TB, are practically incurable by standard first-line treatment. In 2012, there were approximately 450,000 new cases and 170,000 deaths because of MDR-TB. Extensively drug-resistant (XDR) TB refers to MDR-TB strains that are resistant to fluoroquinolones and second-line injectable drugs. The main causes of the spread of resistant TB are weak medical systems, amplification of resistance patterns through incorrect treatment, and transmission in communities and facilities. Although patients harboring MDR and XDR strains present a formidable challenge for treatment, cure is often possible with early identification of resistance and use of a properly designed regimen.

Drug Resistance in Osteoarticular Tuberculosis: A Study From an Endemic Zone.

The present study was undertaken to determine the incidence of drug resistance against anti-tubercular drugs among patients from an endemic zone. Methodology: Forty consecutive clinico-radiologically diagnosed patients of osteoarticular tuberculosis (29: spine, 11: extraspinal) were enrolled. Pus from needle aspiration was taken in 31 cases, tissue following spinal decompression in seven, synovial in one, and sinus edge biopsy in one. The pus/tissue was subjected to acid-fast bacilli (AFB) staining and liquid culture, sensitivity to 13 anti-tubercular drugs (Isoniazid (INH), rifampicin (RIF), kanamycin (KAN), amikacin (AMK,) capreomycin (CAP), ethionamide (ETH), levofloxacin (LEV), moxifloxacin (MOX), linezolid (LNZ), para-amino-salicylic acid (PAS), bedaquiline (BDQ), delamanid (DLM), and clofazimine (CFO)) were checked, and histopathological/cytopathological examination and molecular tests were performed. Results: The mean age of patients was 29.07(9-65) years; 21 were female and 19 were male. The diagnostic accuracy for tuberculosis was 20% by AFB smear, 65% by liquid culture, 82.5% by histopathology, and 90% by cartridge-based nucleic acid amplification testing (CBNAAT). All culture-positive isolates were identified as Mycobacterium tuberculosis with no non-tubercular Mycobacterium. The drug resistance detected on CBNAAT was 11.1%, line probe assay (LPA) first line was 15.4%, LPA second line was 4%, and liquid drug susceptibility testing (DST) 11.5%. We detected 15.4% INHresistance, 11.1% RIF, 7.6% LEV, 3.8% MOX and PAS. No resistance was detected against second-line injectable drugs (SLID), ETH, LNZ, BDQ, DLM, and CFO. Conclusions: No single laboratory modality can ascertain the diagnosis in all cases; hence, samples should be sent for all tests in tandem. In the presence of insufficient samples, tissue may be subjected to CBNAAT and histopathology to arrive at tissue diagnosis. In this subset, overall drug resistance incidence was 12.5% (5/40) with one patient each of isolated INH and RIF resistance, one of multidrug-resistance (MDR), and two of pre-extensively drug-resistant (pre-XDR). Primary drug resistance came out to be 11.1% (4/36) with one patient each of isolated INH and RIF resistance, one ofMDR, and one Pre-XDR.

Poor treatment outcome and associated risk factors among patients with isoniazid mono-resistant tuberculosis: A systematic review and meta-analysis.

To date, isoniazid mono-resistant tuberculosis (TB) is becoming an emerging global public health problem. It is associated with poor treatment outcome. Different studies have assessed the treatment outcome of isoniazid mono-resistant TB cases, however, the findings are inconsistent and there is limited global comprehensive report. Thus, this study aimed to assess the poor treatment outcome and its associated risk factors among patients with isoniazid mono-resistant TB. Studies that reported the treatment outcomes and associated factors among isoniazid mono-resistant TB were searched from electronic databases and other sources. We used Joana Briggs Institute critical appraisal tool to assess the study's quality. We assessed publication bias through visual inspection of the funnel plot and confirmed by Egger's regression test. We used STATA version 17 for statistical analysis. Among 347 studies identified from the whole search, data were extracted from 25 studies reported from 47 countries. The pooled successful and poor treatment outcomes were 78% (95%CI; 74%-83%) and 22% (95%CI; 17%-26%), respectively. Specifically, complete, cure, treatment failure, mortality, loss to follow-up and relapse rates were 34%(95%CI; 17%-52%), 62% (95%CI; 50%-73%), 5% (95%CI; 3%-7%), 6% (95%CI; 4%-8%), 12% (95%CI; 8%-17%), and 1.7% (95%CI; 0.4%-3.1%), respectively. Higher prevalence of pooled poor treatment outcome was found in the South East Asian Region (estimate; 40%, 95%C; 34%-45%), and African Region (estimate; 33%, 95%CI; 24%-42%). Previous TB treatment (OR; 1.74, 95%CI; 1.15-2.33), having cancer (OR; 3.53, 95%CI; 1.43-5.62), and being initially smear positive (OR; 1.26, 95%CI; 1.08-1.43) were associated with poor treatment outcome. While those patients who took rifampicin in the continuation phase (OR; 0.22, 95%CI; 0.04-0.41), had extrapulmonary TB (OR; 0.70, 95%CI; 0.55-0.85), and took second-line injectable drugs (OR; 0.54, 95%CI; 0.33-0.75) had reduced risk of poor treatment outcome. Isoniazid mono-resistant TB patients had high poor treatment outcome. Thus, determination of isoniazid resistance pattern for all bacteriologically confirmed TB cases is critical for successful treatment outcome. PROSPERO registration number: CRD42022372367.

Profile and Frequency of Mutations Conferring Drug-Resistant Tuberculosis in the Central, Southeastern and Eastern Ethiopia.

Advances in molecular tools that assess genes harboring drug resistance mutations have greatly improved the detection and treatment of drug-resistant tuberculosis (DR-TB). This study was conducted to determine the frequency and type of mutations that are responsible for resistance to rifampicin (RIF), isoniazid (INH), fluoroquinolones (FLQs) and second-line injectable drugs (SLIDs) in Mycobacterium tuberculosis (MTB) isolates obtained from culture-positive pulmonary tuberculosis (TB) patients in the central, southeastern and eastern Ethiopia. In total, 224 stored culture-positive MTB isolates from pulmonary TB patients referred to Adama and Harar regional TB laboratories between August 2018 and January 2019 were assessed for mutations conferring RIF, INH, FLQs and SLIDs resistance using GenoType®MTBDRplus (MTBDRplus) and GenoType®MTBDRsl (MTBDRsl). RIF, INH, FLQs and SLIDs resistance-conferring mutations were identified in 88/224 (39.3%), 85/224 (38.0%), 7/77 (9.1%), and 3/77% (3.9%) of MTB isolates, respectively. Mutation codons rpoB S531L (59.1%) for RIF, katG S315T (96.5%) for INH, gyrA A90V (42.1%) for FLQs and WT1 rrs (100%) for SLIDs were observed in the majority of the isolates tested. Over a 10th of rpoB mutations detected in the current study were unknown. In this study, the most common mutations conferring drug resistance to RIF, INH, FLQs were identified. However, a significant proportion of RIF-resistant isolates manifested unknown rpoB mutations. Similarly, although few in number, all SLID-resistant isolates had unknown rrs mutations. To further elucidate the entire spectrum of mutations, tool such as whole-genome sequencing is imperative. Furthermore, the expansion of molecular drug susceptibility testing services is critical for tailoring patient treatment and preventing disease transmission.

Epidemiology of extensively drug-resistant tuberculosis among patients with multidrug-resistant tuberculosis: A systematic review and meta-analysis

ObjectivesTo estimate the pooled proportion of extensively drug-resistant tuberculosis (XDR-TB) and pre-extensively drug-resistant tuberculosis (pre-XDR-TB) in patients with multidrug-resistant TB (MDR-TB). MethodsWe systematically searched articles from electronic databases: MEDLINE (PubMed), ScienceDirect, and Google Scholar. We also searched gray literature from the different literature sources main outcome of the review was either XDR-TB or pre-XDR-TB in patients with MDR-TB. We used the random-effects model, considering the substantial heterogeneity among studies. Heterogeneity was assessed by subgroup analyses. STATA version 14 was used for analysis. ResultsA total of 64 studies that reported on 12,711 patients with MDR-TB from 22 countries were retrieved. The pooled proportion of pre-XDR-TB was 26% (95% confidence interval [CI]: 22-31%), whereas XDR-TB in MDR-TB cases was 9% (95% CI: 7-11%) in patients treated for MDR-TB. The pooled proportion of resistance to fluoroquinolones was 27% (95% CI: 22-33%) and second-line injectable drugs was 11% (95% CI: 9-13%). Whereas the pooled resistance proportions to bedaquiline, clofazimine, delamanid, and linezolid were 5% (95% CI: 1-8%), 4% (95% CI: 0-10%), 5% (95% CI; 2-8%), and 4% (95% CI: 2-10%), respectively. ConclusionThe burden of pre-XDR-TB and XDR-TB in MDR-TB were considerable. The high burdens of pre-XDR-TB and XDR-TB in patients treated for MDR-TB suggests the need to strengthen TB programs and drug resistance surveillance.

Assessment of Amikacin- and Capreomycin-Related Adverse Drug Reactions in Patients with Multidrug-Resistant Tuberculosis and Exploring the Role of Genetic Factors.

Following the introduction of all-oral treatment regimens for patients with drug-resistant tuberculosis (TB), second-line injectable drug applications have been reduced in the last few years. However, they are still important for anti-TB therapy. This study aims to analyze the occurrence of amikacin- and capreomycin-related adverse drug reactions (ADR) in patients with multidrug-resistant tuberculosis (MDR-TB) and evaluate the role of multiple patient-, disease-, and therapy-related factors on the frequency of the observed adverse events. In addition, the possible role of genetic risk factors was studied by full-length mitochondrial DNA sequencing. Toward this aim, we retrospectively evaluated 47 patients with MDR-TB who received amikacin and/or capreomycin. In total, 16 (34.0%) patients developed ototoxicity and 13 (27.7%) developed nephrotoxicity, including 3 (6.4%) patients who experienced both adverse events. Ototoxicity development was more common in patients who received amikacin. No other factors showed a significant impact. Nephrotoxicity was likely associated with previous renal health impairment. Full mitochondrial genome sequencing did not reveal any specific ADR-associated variants, and results showed no differences in adverse event occurrence for any specific variants, mutation count, or mitochondrial haplogroup. The absence of the previously reported ototoxicity-related mtDNA variants in our patients with ototoxicity and nephrotoxicity highlighted the complex nature of the ADR occurrence.