A study on pre-XDR & XDR tuberculosis & their prevalent genotypes in clinical isolates of Mycobacterium tuberculosis in north India

Clinical application of whole-genome sequencing in the management of extensively drug-resistant tuberculosis: a case report

BACKGROUND

Whole-genome sequencing (WGS)-based prediction of drug resistance in Mycobacterium tuberculosis has the potential to guide clinical decisions in the design of optimal treatment regimens.

METHODS

We utilized WGS to investigate drug resistance mutations in a 32-year-old Tanzanian male admitted to Kibong'oto Infectious Diseases Hospital with a history of interrupted multidrug-resistant tuberculosis treatment for more than three years. Before admission, he received various all-oral bedaquiline-based multidrug-resistant tuberculosis treatment regimens with unfavourable outcomes.

RESULTS

Drug susceptibility testing of serial M. tuberculosis isolates using Mycobacterium Growth Incubator Tubes culture and WGS revealed resistance to first-line anti-TB drugs, bedaquiline, and fluoroquinolones but susceptibility to linezolid, clofazimine, and delamanid. WGS of serial cultured isolates revealed that the Beijing (Lineage 2.2.2) strain was resistant to bedaquiline, with mutations in the mmpR5 gene (Rv0678. This study also revealed the emergence of two distinct subpopulations of bedaquiline-resistant tuberculosis strains with Asp47f and Glu49fs frameshift mutations in the mmpR5 gene, which might be the underlying cause of prolonged resistance. An individualized regimen comprising bedaquiline, delamanid, pyrazinamide, ethionamide, and para-aminosalicylic acid was designed. The patient was discharged home at month 8 and is currently in the ninth month of treatment. He reported no cough, chest pain, fever, or chest tightness but still experienced numbness in his lower limbs.

CONCLUSION

We propose the incorporation of WGS in the diagnostic framework for the optimal management of patients with drug-resistant and extensively drug-resistant tuberculosis.

[Pre-extensively and extensively drug-resistant tuberculosis, in Libreville, Gabon]

INTRODUCTION

Very few studies have been devoted to extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis (TB) in Gabon.

AIM

The aim of the present study is to present the epidemiology of pre-XDR and XDR TB and the evolution over time of patients with multidrug-resistant TB.

METHODS

This retrospective study covered the activities from 2019 to 2022 of the Nkembo anti-tuberculosis center.

RESULTS

Fifteen patients were eligible, including 11 (73.3%) pre-XDR patients and 4 (26.7%) XDR-TB patients. Three (20.0%) patients had HIV/TB co-infection. The sample consisted of 7 men (46.7%) and 8 women (53.3%), a sex ratio (M/F) of 0.87. The average age was 35.6 years, and the median 34 years, with extremes of 23 and 60 years. Eight patients (53.3%) represented new cases of pre-XDR or XDR-TB tuberculosis. The majority (60%; n=9) came from deprived neighborhoods with widespread promiscuity. The therapeutic success rate among pre-XDR patients was 4 (36.4%) versus 2 (50.0%) among XDR-TB patients. Reported mortality occurred 5 (33.3%) patients during treatment, including 3 pre-XDR and 2 XDR-TB patients. In all cases, they died before the end of the first trimester of follow-up.

CONCLUSION

The high frequency of primary pre-extensively drug-resistant tuberculosis underscores the pervasiveness of resistance to anti-tuberculosis drugs and underlines a pressing need for detection of contact cases and early treatment.

Drug-resistant Mycobacterium tuberculosis among Nepalese patients at a tuberculosis referral center

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB), characterized by isoniazid and rifampicin resistance, is caused by chromosomal mutations that restrict treatment options and complicate tuberculosis management. This study sought to investigate the prevalence of pre-extensively drug-resistant (pre-XDR) and extensively drug-resistant (XDR) tuberculosis, as well as mutation pattern, in Nepalese patients with MDR/rifampicin-resistant (RR)-TB strains.

METHODS

A cross-sectional study was conducted on MDR/RR-TB patients at the German Nepal Tuberculosis Project from June 2017 to June 2018. The MTBDRsl line probe assay identified pre-XDR-TB and XDR-TB. Pre-XDR-TB included MDR/RR-TB with resistance to any fluoroquinolone (FLQ), while XDR-TB included MDR/RR-TB with resistance to any FLQ and at least one additional group A drug. Mutation status was determined by comparing bands on reaction zones [gyrA and gyrB for FLQ resistance, rrs for SILD resistance, and eis for low-level kanamycin resistance, according to the GenoType MTBDRsl VER 2.0, Hain Lifescience GmbH, Nehren, Germany definition of pre-XDR and XDR] to the evaluation sheet. SPSS version 17.0 was used for data analysis.

RESULTS

Out of a total of 171 patients with MDR/RR-TB, 160 had (93.57%) had MTBC, of whom 57 (35.63%) had pre-XDR-TB and 10 (6.25%) had XDR-TB. Among the pre-XDR-TB strains, 56 (98.25%) were FLQ resistant, while 1 (1.75%) was SLID resistant. The most frequent mutations were found at codons MUT3C (57.14%, 32/56) and MUT1 (23.21%, 13/56) of the gyrA gene. One patient had SLID resistant genotype at the MUT1 codon of the rrs gene (100%, 1/1). XDR-TB mutation bands were mostly detected on MUT1 (30%, 3/10) of the gyrA and rrs, MUT3C (30%, 3/10) of the gyrA, and MUT1 (30%, 3/10) of the rrs.

CONCLUSIONS

Pre-XDR-TB had a significantly higher likelihood than XDR-TB, with different specific mutation bands present in gyrA and rrs genes.

Multilevel Pre-extensively Drug-resistant Tubercular Spondylodiscitis: Underdiagnosed or Overlooked? A Case Report

Introduction

Pre-extensively drug-resistant tuberculosis (TB) is characterized by resistance to either a fluoroquinolone (FQ) or a second-line injectable but not both. The urgent need for prompt diagnosis and targeted treatment is emphasized. This report aims to spotlight a case of spinal TB with insufficient assessment, resulting in delayed definitive treatment and an oversight contributing to heightened morbidity.

Case Report

An 18-year-old female who was initially diagnosed to have multidrug-resistant TB leading to a 2-year treatment which eventually resulted in multifocal involvement of the spine revealing TB relapse with FQ resistance, categorized as pre-extensively drug-resistant TB. Treatment was shifted to newer drugs, addressing challenges like bilateral psoas abscess, which lead to clinical improvement, allowing the patient to make a good recovery.

Conclusion

This case report emphasizes the significance of conducting culture and drug sensitivity testing in patients with tubercular spondylodiscitis. The aim is to prevent misdiagnosis and ensure informed decisions regarding definitive medical treatment or surgical management when necessary.

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

OBJECTIVES

To 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).

METHODS

We 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.

RESULTS

A 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.

CONCLUSION

The 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.

Primary Disseminated Pre-extensively Drug-Resistant Tuberculosis of the Lungs, Pleura, Chest Wall, and Abdomen: The World's First Case

Drug-resistant tuberculosis is a perpetual threat to public health. In recent years, there has been an increase in the number of cases of this deadly Mycobacterium tuberculosis infection. The present case is a very rare case of primary disseminated pre-extensively drug-resistant tuberculosis of the lungs, pleura, chest wall, and abdomen in a 19-year-old Indian female patient who presented with fever, cough, abdominal pain, and anterior chest wall swelling. The diagnosis was established by a detailed laboratory and radiological workup. An all-oral longer regimen was initiated per national guidelines and according to her weight.

Pre-extensively drug-resistant tuberculosis among multidrug-resistant tuberculosis patients in Ethiopia: a laboratory-based surveillance study

Background

The rise of drug-resistant tuberculosis (DR-TB) has presented a substantial challenge to the national tuberculosis (TB) control program. Understanding the epidemiology of pre-extensively drug-resistant tuberculosis (pre-XDR-TB) could help clinicians to adapt MDR-TB treatment regimens at an earlier stage. This study aimed to assess second-line anti-TB drug resistance among MDR-TB patients in Ethiopia using routine laboratory-based data.

Methods

Laboratory-based cross-sectional data were collected from the national TB reference laboratory and seven regional tuberculosis culture laboratories in Ethiopia from July 2019 to March 2022. The required data, such as drug-susceptibility testing (DST) results and sociodemographics, were collected on a structured checklist from laboratory registration books and electronic databases. Data were entered into a Microsoft Excel spreadsheet and analyzed using SPSS version 23. Descriptive statistics were performed to show the distribution and magnitude of drug resistance.

Results

Second-line drugs (SLDs) susceptibility testing was performed for 644 MDR isolates, of which 19 (3%) were found to be pre-XDR-TB cases. Of the total MDR-TB isolates, 19 (3%) were resistant to at least one fluoroquinolone drug, while 11 (1.7%) were resistant to at least one injectable second-line drug. Of the 644 MDR-TB isolates, 1.9% (5/261) pre-XDR were from new MDR-TB cases, while 3.7% (14/383) were from previously treated MDR-TB patients. The most frequently identified mutations, based on MTBDRsl results, were in codon A90V of the gyrA gene (77.3%) and A1401G of the rrs gene (45.5%).

Conclusion

The overall prevalence of pre-XDR-TB in Ethiopia is considerable. The majority of SLD resistance mutations were in the gyrA gene at position A90V. Modern, rapid DST is necessary to enable identification of pre-XDR-TB and XDR-TB in supporting proper regimen administration for patients.

24 loci MIRU-VNTR analysis and pattern of drug resistance in pre-extensively drug resistant pulmonary tuberculosis in Bangladesh

Phylogenetic diversity and distinct phylogeographic distribution of Mycobacterium tuberculosis (MTB) contribute to regional differences in drug resistance. The emergence of pre-extensively drug resistant tuberculosis (Pre-XDR-TB) becomes obstacles to achieve End TB strategy in Bangladesh. This cross-sectional study was conducted to identify the strains of different lineages of MTB, their variations of distribution among Pre-XDR-TB cases and to observe the linkage of particular strains of MTB with drug resistance. A total of 33 Pre-XDR-TB isolates were enrolled in this study. All isolates were confirmed as MTB by MPT 64 antigen detection and genotyped by 24 loci Mycobacterial Interspersed Repetitive Unit-Variable Number of Tandem Repeats (MIRU-VNTR) analysis. Drug resistance was detected by second line Line probe assay (LPA). Beijing was the predominant strain 16 (48.48%), followed by Delhi/CAS 5(15.15%), LAM 4 (12.12%) and Harlem 3(9.10%), EAI 2(6.06%), Cameroon 2(6.06%) and NEW-1 1(3.03%). There were 31 different genotypes consisting of 2 clusters and 29 singletons. All the clustered strains were belonged to Beijing lineage. Recent transmission occurred manly by Beijing strains, showed low transmission rate (12.1%). Of 33 isolates 30(90.90%) were Fluoroquinolones resistant, the mutations involved was Asp94Gly in gyr A MUT 3C gene 13(39.39%) in quinolone resistance determining region (QRDR) followed by 11 (33.33%) in gyr A MUT 1. Three (9.10%) isolates showed resistant to injectable 2nd line drugs and all mutation occurs in G1484T of rrs MUT 2. Beijing lineage was predominant in treatment failure and relapse cases. Levofloxacin was resistant to all Pre-XDR-TB cases, but moxifloxacin showed low level resistance. QUB 26 was the most discriminatory locus (0.85) among 24 loci whereas MIRU 2 was the least (0.03). 24 loci MIRU-VNTR analysis shows high discriminatory index (0.71), found to be powerful tool for genotyping of Pre-XDR-TB, which is the first study in Bangladesh that enhanced the current TB control policy.

Laboratory-based study of drug resistance and genotypic profile of multidrug-resistant tuberculosis isolates in Salvador, Bahia, Brazil

Background:

Surveillance of multidrug resistant/extensively drug-resistant tuberculosis (MDR/XDR-TB) is essential to guide disease dissemination control measures. Brazil contributes to a significant fraction of tuberculosis (TB) cases worldwide, but only few reports addressed MDR/XDR-TB in the country.

Methods:

This cross-sectional, laboratory-based study describes the phenotypic resistance profiles of isolates obtained between January 2008 and December 2011 in Bahia, Brazil, and sociodemographic, epidemiological, and clinical characteristics (obtained from mandatory national registries) of the corresponding 204 MDR/XDR-TB patients. We analyzed the mycobacterial spoligotyping and variable number of tandem repeats of mycobacterial interspersed repetitive units in 12-loci profiles obtained from Salvador.

Results:

MDR/XDR-TB patients were predominantly male, had a median age of 43 years, belonged to black ethnicity, and failed treatment before MDR-TB diagnosis. Nearly one-third of the isolates had phenotypic resistance (evaluated by mycobacteria growth indicator tube assay) to second-line anti-TB drugs (64/204, 31%), of which 22% cases (14/64) were diagnosed as XDR-TB. Death was a frequent outcome among these individuals and was associated with resistance to second-line anti-TB drugs. Most isolates successfully genotyped belonged to the Latin-American Mediterranean (LAM) Family, with an unprecedented high proportion of LAM10-Cameroon subfamily bacilli. More than half of these isolates were assigned to a unique cluster by the genotyping methods performed. Large clusters of identical genotypes were also observed among LAM SIT42 and SIT376 strains.

Conclusions:

We highlight the need for strengthening local and national efforts to perform early detection of TB drug resistance and to prevent treatment discontinuation to limit the emergence of drug-resistant strains.

Risk Factors and Treatment Outcome Analysis Associated with Second-Line Drug-Resistant Tuberculosis

The present study aimed at analyzing the treatment outcomes and risk factors associated with fluoroquinolone drug resistance having mutations in the gyrA and gyrB genes. A total of 258 pulmonary tuberculosis samples with first-line drug-resistant (H, R, or HR) were subjected to GenoType MTBDRsl assay for the molecular detection of mutations. Among the 258 samples, 251 were drug-resistant tuberculosis and seven were sensitive to all first-line TB drugs. Out of 251 DR-TB cases, 42 cases were MDR TB, 200 were INH mono-resistant and nine cases were RIF mono-resistant tuberculosis. Out of 251 DR-TB cases performed with a MTBDRsl assay, 14 had Pre-XDR-FQ, one patient had pre-XDR-SLID, one had extensively drug-resistant tuberculosis (XDR-TB) and 235 cases were sensitive to both FQ and SLID drugs. The study group had a mean average of 42.7 ± 16.4 years. The overall successful treatment outcomes among the MDR, INH mono-resistant, and pre-XRD patients were 70.6%, 82.0%, and 51%, respectively. The percentage of risk for the unfavorable outcomes in the pre-XDR, INH -mono-resistant, and XDR cases were 113.84% increased risk with RR 2.14; 95% CI 0.7821–5.8468. The independent risk factor associated with the unfavorable outcomes to failure was 77.78% increased risk with RR 1.78; 95% CI 0.3375–9.3655. Logistic regression analysis revealed that the percentage relative risk among MDR-TB patients for gender, male (RR: 1.85), age ≥ 61 years (RR: 1.96), and diabetics (RR: 1.05) were 84.62%, 95.83%, and 4.76%, respectively. The independent risk factors associated with INH mono-resistant cases of age 16–60 (RR: 1.86), ≥61 year (RR: 1.18), and treated cases (RR: 5.06). This study presaged the significant risk of INH mono-resistant, pre-XDR, and MDR among males, young adults, diabetics, and patients with previous treatment failure. Timely identification of high-risk patients will give pronounced advantages to control drug resistance tuberculosis diseases.

Beijing genotype of Mycobacterium tuberculosis is associated with extensively drug-resistant tuberculosis: A global analysis

We found that the frequency of Beijing genotype among XDR-TB strains was high. The data in this study would help guide the TB control program, and we however need further investigation to confirm the reliability of the present findings.

Tuberculosis: An Overview of the Immunogenic Response, Disease Progression, and Medicinal Chemistry Efforts in the Last Decade toward the Development of Potential Drugs for Extensively Drug-Resistant Tuberculosis Strains

Tuberculosis (TB) is a slow growing, potentially debilitating disease that has plagued humanity for centuries and has claimed numerous lives across the globe. Concerted efforts by researchers have culminated in the development of various strategies to combat this malady. This review aims to raise awareness of the rapidly increasing incidences of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis, highlighting the significant modifications that were introduced in the TB treatment regimen over the past decade. A description of the role of pathogen-host immune mechanisms together with strategies for prevention of the disease is discussed. The struggle to develop novel drug therapies has continued in an effort to reduce the treatment duration, improve patient compliance and outcomes, and circumvent TB resistance mechanisms. Herein, we give an overview of the extensive medicinal chemistry efforts made during the past decade toward the discovery of new chemotypes, which are potentially active against TB-resistant strains.

Second-line Drug Resistance Characterization in Mycobacterium tuberculosis by Genotype MTBDRsl Assay

Tuberculosis (TB) remains a main hurdle for national programs due to increase in drug resistance to antitubercular drugs. World Health Organization (WHO)-endorsed Line Probe Assay, Genotype MTBDRsl Ver 2.0, gives opportunity for rapid diagnosis and molecular characterization of different mutations in drug targets of fluoroquinolone (FQ) and second-line injectable drugs (SLID). We, retrospectively, analyzed the data of Genotype MTBDRsl Ver 2.0 from January 2018 to June 2018. A total of 863 isolates of Mycobacterium tuberculosis, 687 rifampicin resistant and 176 isoniazid resistant only, were screened for drug resistance in FQ and SLID. All the isolates were tested for Genotype MTBDRsl Ver 2.0 according to the manufacturer’s instructions. The FQ and SLID resistance were detected in 295 (34.2%) and 70 (8.1%) isolates, respectively. Among newly diagnosed and follow-up rifampicin-resistant TB (RR TB) patients, the FQ resistance was 25.8% and 44.5%, respectively. The most common mutation (42.7%) in FQ-resistant isolates was MUT3C in gyrA gene. Both SLID and FQ resistance were detected in 59 (6.8%) RR TB isolates. The mono SLID resistance was detected in 12 (1.7%) isolates of RR TB. Genotype MTBDRsl Ver 2.0 assay is a rapid and important tool for the diagnosis and molecular characterization of second-line drug resistance under programmatic conditions.

Genotype analysis of ofloxacin-resistant multidrug-resistant Mycobacterium tuberculosis isolates in a multicentered study from India

Background & objectives:

Drug resistance surveillance offers useful information on trends of drug resistance and the efficacy of control measures. Studies and reports of drug-resistant mutations and phenotypic assays thus become important. This study was conducted to investigate the molecular characteristics of ofloxacin (OFX)-resistant, multidrug-resistant tuberculosis (MDR-TB) isolates from different geographical regions of India and their association with strains of different genotypes. Further, the nitrate reductase assay (NRA) was tested against Mycobacteria Growth Indicator Tube (MGIT) for the determination of OFX resistance as an alternative and cost-effective method.

Methods:

A total of 116 Mycobacterium tuberculosis isolates were used to assess the mutations in the gyrA, gyrB genes and resistance levels to OFX. Mutational analysis in gyrA and gyrB genes and genotype analysis of M. tuberculosis isolates was done by gene-specific polymerase chain reaction (PCR) followed by DNA sequencing and spoligotyping, respectively.

Results:

Three (6.25%), 12 (44.44%) and 12 (29.27%) MDR-TB isolates from western, northern and southern India, respectively, were found to be OFX-resistant MDR-TB isolates. OFX resistance was observed to be significantly higher in MDR-TB cases for all study regions. Beijing genotypes from northern India were observed to be associated with OFX-resistant MDR-TB cases (P<0.05). Among 35 (30.15%) phenotypically OFX-resistant isolates, 22 (62.86%) had mutations in the gyrA gene and two (5.71%) isolates had mutations in the gyrB gene.

Interpretation & conclusions:

These results caution against the PCR-based prediction of OFX resistance patterns and highlight the need for searching other genetic loci for the detection of mutations conferring resistance to OFX in M. tuberculosis. Our study also showed the usefulness of NRA as an alternative method to detect OFX resistance.

Second Line Injectable Drug Resistance and Associated Genetic Mutations in Newly Diagnosed Cases of Multidrug-Resistant Tuberculosis

Aim: To investigate the phenotypic and genotypic profile of multidrug-resistant (MDR) Mycobacterium tuberculosis (MTB) clinical isolates with reference to second-line injectable drugs (SLIDs). Methods: A total of 110 MTB isolates, recovered consecutively from confirmed MDR-TB patients between March and June 2016, were included in this study. Phenotypic drug susceptibility testing against SLIDs (Kanamycin, Amikacin, and Capreomycin) and Ofloxacin (OFX) was performed using the MGIT 960 system. For genotypic analysis, SLID/(s) resistant (n = 13) and susceptible isolates (n = 26) were subjected to PCR and DNA sequencing for rrs, eis (promoter region), and tlyA loci of MTB. Furthermore, the identified genetic mutations were analyzed with respect to its significance in detecting phenotypic resistance. Result: Among the 110 analyzed isolates, phenotypic resistance to OFX, SLIDs, and to both was 59.1%, 11.8%, and 10.0%, respectively. Out of a total 13 SLID/(s) resistant isolates, 10 had mutations (including two novel mutations) in one or more of the targeted genes. Only one SLID susceptible MTB isolate showed mutation in the targeted region. In SLID resistant isolates, most frequent mutation detected was C-12T under eis promoter region (46.1%). Conclusion: Mutations in rrs, eis, and tly A loci together are important in predicting SLID resistance in MTB isolates. Future molecular epidemiology studies are needed to have more insight into frequency and clinical relevance of novel mutations identified in this study.

Burden of baseline resistance of Mycobacterium tuberculosis to fluoroquinolones and second-line injectables in central India

Background

Drug-resistant TB is a serious public health problem in India. Pre-existing resistance to fluoroquinolones (FQs) and second-line injectable drugs (SLIDs) in strains of Mycobacterium tuberculosis (MTB) resistant to rifampicin (RIF) and/or isoniazid (INH) contributes to treatment failures and consequent transmission of drug-resistant TB. A baseline assessment of resistance of MTB to FQs and SLIDs may help guide policies to further improve management of drug-resistant TB in India. This study aims to determine the prevalence of resistance to FQs and SLIDs among MTB strains having RIF and/or INH resistance in central India.

Method

A total of 1032 smear positive sputum samples were subjected to line probe assay (GenoType MTBDRsl version 2) to test for resistance to FQs and SLIDs, according to the integrated diagnostic algorithm of the revised national TB control programme.

Results

Of 1032 samples, 92 (8.91%) were not interpretable and hence excluded, 295 (31.38%) were resistant to FQs alone, 13 (1.38%) were resistant to SLIDs alone, 15 (1.59%) were resistant to both FQs as well as SLIDs and 617 (65.63%) were sensitive to both FQs and SLIDs. The most common mutations in gyrA and gyrB genes were observed at codons D94G and E540V, respectively. Mutations at codon A1401G in rrs genes and in the C-14 T region of eis genes were most frequently observed.

Conclusion

High levels of FQ resistance points towards indiscriminate use of this class of drugs. Regulation for judicial use of FQs is an urgent requirement.

High degree of fluoroquinolone resistance among pulmonary tuberculosis patients in New Delhi, India

Background & objectives:

The fluoroquinolones (FQs) group of antibiotics is the backbone drugs for the management of drug-resistant tuberculosis (TB). In routine clinical practice, drug susceptibility testing (DST) for FQs is not performed, and the patients are empirically treated. A limited information exists regarding FQs resistance among pulmonary TB cases. The present study was conducted to determine the FQs resistance among drug sensitive and drug-resistant pulmonary TB patients in a tertiary care centre in north India.

Methods:

A total of 1619 sputum/smear-positive specimens of pulmonary TB patients were subjected to DST for first-line drugs (FLDs) and second-line drugs. In addition, FQs DST was also performed using automated Mycobacterial Growth Indicator Tube-960 liquid culture technique. The immuno-chromatographic assay was performed to distinguish Mycobacterium tuberculosis complex (MTBC) from non-MTBC.

Results:

Mycobacterium tuberculosis (Mtb) was isolated in 1499 sputum specimens; 1099 culture specimens were sensitive to FLDs, 249 grew as multidrug-resistant (MDR) Mtb and the remaining 151 isolates revealed any drug resistance to FLDs. While FQs monoresistance among the FLD sensitive isolates was 3.1 per cent (35/1099), 27.3 per cent (68/249) among MDR Mtb isolates had additional FQs resistance.

Interpretation & conclusions:

FQs resistance among drug sensitive and MDR Mtb isolates was high in Delhi, India. Based on these findings, it is recommended that the DST for FQs should be routinely performed to avoid further amplification of drug resistance.

Synthesis and biological evaluation of 2,4,5-trisubstituted thiazoles as antituberculosis agents effective against drug-resistant tuberculosis

The dormant and resistant form of Mycobacterium tuberculosis presents a challenge in developing new anti-tubercular drugs. Herein, we report the synthesis and evaluation of trisubstituted thiazoles as antituberculosis agents. The SAR study has identified a requirement of hydrophobic substituent at C2, ester functionality at C4, and various groups with hydrogen bond acceptor character at C5 of thiazole scaffold. This has led to the identification of 13h and 13p as lead compounds. These compounds inhibited the dormant Mycobacterium tuberculosis H37Ra strain and M. tuberculosis H37Rv selectively. Importantly, 13h and 13p were non-toxic to CHO cells. The 13p showed activity against multidrug-resistant tuberculosis isolates.

Novel 1,3,4-oxadiazoles as antitubercular agents with limited activity against drug-resistant tuberculosis

AIM

In recent times, heterocyclic chemotypes are being explored for the development of new antimycobacterials that target the drug-resistant tuberculosis. Here, we are disclosing the 5-substitued 2-mercapto-1,3,4-oxadiazoles as potent antitubercular agents.

METHODOLOGY

A small library of 2-mercapto-1,3,4-oxadiazoles was synthesized using various acids. The compounds were evaluated for antituberculosis activity against M. tuberculosis H37Rv.

RESULTS

Compound 8j was identified as antitubercular lead with MIC of 0.6 μg/ml against M. tuberculosis H37Rv. This compound was nontoxic to CHO-K1 cells and showed selectivity index of 39. Of note, 8j showed antitubercular activity against pre-extensively drug-resistant clinical isolate of Mycobacterium with MIC of 2 μg/ml.

CONCLUSION

This study provides potent antitubercular agent which can be further optimized to discover novel antibiotics.

First insights on the genetic diversity of MDR Mycobacterium tuberculosis in Lebanon

Background

Lebanon hosts a heterogeneous population coming from underdeveloped and developing countries, resulting in increasing incidences of tuberculosis over the past years. The genetic heterogeneity and lineages associated with tuberculosis, along with their resistance determinants have not been studied at the genomic level previously in the region.

Methods

Isolates were recovered from the American University of Beirut Medical Center (AUBMC). Antimicrobial susceptibility profiles were determined using the MGIT automated system for the first-line drugs at AUBMC, while second-line drug susceptibility was tested at Mayo Clinic Laboratories. Whole Genome Sequencing (WGS) was performed to classify mycobacterial lineages and highlight single nucleotide mutations causing resistance to both 1st line and 2nd line antimicrobials. wgSNP analysis provided insights on the phylogeny of the isolates along with spoligotyping and core genomic SNVs, IS6110 insertion sites, and variable number tandem repeats (VNTR).

Results

The analyzed isolates carry distinct resistance determinants to isoniazid, rifampicin, ethambutol, quinolones, and streptomycin. The isolates belonged to different lineages including the Euro/American lineage (Lineage 4) (53.8%), M. bovis (15.4%) and Delhi/Central Asia (Lineage 1) (15.4%), Beijing/East Asia (Lineage 2) (7.7%), and East Africa/Indian Ocean lineage (Lineage 3) (7.7%) showing great phylogenetic differences at the genomic level.

Conclusions

The population diversity in Lebanon holds an equally diverse and uncharacterized population of drug resistant mycobacteria. To achieve the WHO “END-TB” milestones of 2025 and 2035, Lebanon must decrease TB incidences by 95% in the next decade. This can only be done through WGS-based patient centered diagnosis with higher throughput and genomic resolution to improve treatment outcomes and to monitor transmission patterns.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3626-3) contains supplementary material, which is available to authorized users.

Characterization of Mycobacterium tuberculosis strains in Beijing, China: drug susceptibility phenotypes and Beijing genotype family transmission

Background

The most prevalent strains of Mycobacterium tuberculosis (M.tb) in Beijing belong to the Beijing genotype family. The influence of Beijing genotype prevalence on the development of drug resistance, and the association of infection with Beijing genotype M.tb with population characteristics, in Beijing, however, are still unclear.

Methods

In this retrospective study, 1189 isolates were subjected to drug susceptibility testing (DST) and molecular epidemiological analysis, and differences in the percentage of drug resistance between Beijing and non-Beijing genotype strains were compared. The association between the occurrence of drug resistance and the prevalence of Beijing genotype M.tb was analyzed using statistical methods.

Results

The Beijing genotype family was the dominant genotype (83.3%) among the 1189 M.tb isolates. Beijing genotype M.tb strains were more likely to spread among males [p = 0.018, OR (95% CI):1.127(1.004–1.264)] and people in the 45–64 age group [p = 0.016, OR (95% CI): 1.438 (1.027–2.015)]. On the contrary, non-Beijing genotype M.tb strains were more probably disseminated among the over 65 [p = 0.005, OR (95% CI):0.653 (0.474–0.9)] and non-resident population [p = 0.035, OR (95% CI):1.185(0.985–1.427)]. DST results showed that 849 (71.4%) strains were fully sensitive to first-line drugs, while 340 (28.6%) strains were resistant to at least one drug, and 9% (107/1189) were MDR-TB. The frequency of INH-resistance among Beijing genotype strains was significantly lower than that among non-Beijing genotype strains (p = 0.032). In addition, the Beijing genotype family readily formed clusters.

Conclusions

Our findings indicate that male and middle-aged people were more probably be infected by Beijing genotype M.tb, older people and non-residents were more probably be infected by non-Beijing genotype M.tb. The high percentage of resistance to INH occurring in non-Beijing genotype strains suggested that non-Beijing genotype strains should be given much more interest in Beijing.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3578-7) contains supplementary material, which is available to authorized users.

A study on pattern of resistance to second line anti tubercular drugs among multi drug resistant tuberculosis patients

AIMS AND OBJECTIVES

To determine the prevalence and pattern of resistance to second line drugs among multi drug resistant (MDR) tuberculosis patients being treated on category IV regimen.

METHODOLOGY

This study was conducted at Department of Respiratory Medicine, J.L.N. Medical College, Ajmer in collaboration with IRL, STDC, Ajmer. Second line anti tubercular drug sensitivity for 398 multi drug resistant tuberculosis patients (between June-2015 and June-2016) was done to find out prevalence and pattern of resistance to second line drugs. Second line drug sensitivity was performed at accredited laboratory, Microbiology department, S.M.S. Medical College, Jaipur.

RESULTS

Among these 398 patients, 136 (34.17%) were resistant to fluoroquinolones (Ofloxacin) (Pre XDR); 18 (4.52%) were resistant to one of the aminoglycosides (Inj. Kanamycin, Capreomycin, Amikacin) (Pre XDR); while 22 (5.53%) patients were resistant to fluoroquinolones as well as aminoglycosides (XDR). 148 (37.18%) patients were found sensitive to both the drugs. Samples of 41 (10.3%) patients were contaminated and no growth was seen in 33 (8.29%) patients.

CONCLUSION

Nearly half of the multi drug resistant (MDR) tuberculosis patients (44.22%) being treated on category IV regimen also have resistance to either fluoroquinolones or aminoglycosides or both i.e. Pre XDR or XDR. This may result in poor outcome of category IV regimen under RNTCP. There is a strong need for provision of culture sensitivity for all first line drugs and at least two second line drugs viz. Fluoroquinolones and aminoglycosides for all the patients registered as smear positive under RNTCP. There is also a need for development of rapid culture technique for sensitivity to second line drugs.

Initial second-line drug resistance of Mycobacterium tuberculosis isolates from Sudanese retreatment-patients

SETTING

Multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) are a major public health threat.

OBJECTIVE

This study aimed to determine resistance patterns to second line anti-TB drugs (SLDs), and to determine the frequency of extensively drug resistant Mycobacterium tuberculosis (XDR-TB).

DESIGN

During the period from July 2009 to July 2010; sputum specimens were collected from TB retreatment patients; isolates were tested for sensitivity to first line anti-TB drugs by the 1% proportion method; MDR strains were tested for second line anti-TB drugs sensitivity by 1% proportion method and by version 1. Hain GenoType MTBDRsl Assay.

RESULTS

One hundred and forty three mycobacterial isolates were successfully recovered from a total of 239 specimens (143/239; 59.8%). Fifty six strains were rifampicin resistant (RR); of these 54 were multi-drug resistant (MDR); two were RIF/INH-resistant mycobacterium other than tuberculosis (MOTT). Five of MDR (5/50; 10%) showed resistance to at least one second line drug and one isolate (1/50; 2%) was XDR. The XDR strain was concordantly detected by the two methods.

CONCLUSION

Initial resistance to second line anti-TB drugs among MDR-TB patients is at 10% levels and XDR-TB is prevalent at low levels (2%). Nevertheless; without great efforts from national tuberculosis control program (NTP) this figure can fuel the TB epidemics in Sudan.

The study on the association between Beijing genotype family and drug susceptibility phenotypes of Mycobacterium tuberculosis in Beijing

The predominant prevalent Mycobacterium tuberculosis (M. tb) lineage was the Beijing genotype family in Beijing. There has been no systematic study on the association between drug resistance and Beijing genotype. Here we collected 268 M. tb strains, analyzed the background information and the bacteriological characteristics. The mean age of the cases was 40.12 years; male patients were almost three times than female patients. After genotyping analyzation, 81.7% (219/268) strains were categorized as Beijing genotype; no significant difference was observed between Beijing and non-Beijing genotype in gender, age and treatment history. Drug susceptibility testing (DST) analyzation demonstrated that 172 (64.2%) strains were fully sensitive to all drugs (Isoniazid, Rifampin, Streptomycin, and Ethambutol), while 96 (35.8%) strains were resistant to at least one of the drugs. Beijing genotype strains exhibited a significantly higher clustering rate. However, no significant association relationship was observed between drug resistance and Beijing genotype family. The study provided insights into the genotype diversity and revealed that the frequencies of drug-resistance of Beijing genotype strains.It would be helpful for the establishment of the efficient tuberculosis (TB) prevention and control strategy in Beijing.

Molecular epidemiology of multi- and extensively-drug-resistant Mycobacterium tuberculosis in Ireland, 2001-2014

OBJECTIVES

The primary objective of this work was to examine the acquisition and spread of multi-drug resistant (MDR) tuberculosis (TB) in Ireland.

METHODS

All available Mycobacterium tuberculosis complex (MTBC) isolates (n = 42), from MDR-TB cases diagnosed in Ireland between 2001 and 2014, were analysed using phenotypic drug-susceptibility testing, Mycobacterial-Interspersed-Repetitive-Units Variable-Number Tandem-Repeat (MIRU-VNTR) genotyping, and whole-genome sequencing (WGS).

RESULTS

The lineage distribution of the MDR-TB isolates comprised 54.7% Euro-American, 33.3% East Asian, 7.2% East African Indian, and 4.8% Indo-Oceanic. A significant association was identified between the East Asian Beijing sub-lineage and the relative risk of an isolate being MDR. Over 75% of MDR-TB cases were confirmed in non-Irish born individuals and 7 MIRU-VNTR genotypes were identical to clusters in other European countries indicating cross-border spread of MDR-TB to Ireland. WGS data provided the first evidence in Ireland of in vivo microevolution of MTBC isolates from drug-susceptible to MDR, and from MDR to extensively-drug resistant (XDR). In addition, they found that the katG S315T isoniazid and rpoB S450L rifampicin resistance mutations were dominant across the different MTBC lineages.

CONCLUSIONS

Our molecular epidemiological analyses identified the spread of MDR-TB to Ireland from other jurisdictions and its potential to evolve to XDR-TB.

Current and developing therapies for the treatment of multi drug resistant tuberculosis (MDR-TB) in India

INTRODUCTION

India accounts for 25% of the global burden of MDR-TB. In 2016, the India's Revised National TB Control Programme reported a success rate of 46% among 19,298 MDR-TB patients treated under the programme. This suboptimal treatment outcome warrants an urgent need for newer drugs and newer regimens in the treatment of MDR-TB. India requires new shorter, cheap, safe and effective anti-TB regimen to treat MDR-TB. Areas covered: We used different search strategies to obtain relevant literature from PubMed, on Indian experiences of developing therapies for the treatment of MDR-TB. Further information from the Central TB Division Government of India on programmatic management of resistant TB was collected. Expert opinion: In 2016 WHO recommended a shorter MDR-TB regimen of 9-12 months (4-6 Km-Mfx-Pto-Cfz-Z-Hhigh-dose-E /5 Mfx-Cfz-Z-E) may be used instead of longer regimens. Currently, conducting trials involving newer drugs such as bedaquiline, have been proposed. The regimen will be of a shorter duration containing isoniazid, prothionamide, bedaquiline, levofloxacin, ciprofloxacin, ethambutol and pyrazinamide (STREAM regimen). To successfully treat MDR-TB one requires new classes of antibiotic and newer diagnostic tests. This represents an enormous financial and technical challenge to the programme managers and policy makers.