Magnitude of Phenotypic and MTBDRplus Line Probe Assay First-Line Anti-Tuberculosis Drug Resistance Among Tuberculosis Patients; Northwest Ethiopia

Drug resistance profiles of Mycobacterium tuberculosis clinical isolates by genotype MTBDRplus line probe assay in Zambia: findings and implications

Background

The emergence of drug resistance is a threat to global tuberculosis (TB) elimination goals. This study investigated the drug resistance profiles of Mycobacterium tuberculosis (M. tuberculosis) using the Genotype MTBDRplus Line Probe Assay at the National Tuberculosis Reference Laboratory (NTRL) in Zambia.

Methods

A cross-sectional study was conducted between January 2019 and December 2020. GenoType MTBDRplus line probe assay records for patients at the NTRL were reviewed to investigate drug susceptibility profiles of M. tuberculosis isolates to rifampicin and isoniazid. Data analysis was done using Stata version 16.1.

Results

Of the 241 patient records reviewed, 77% were for females. Overall, 44% of patients were newly diagnosed with TB, 29% had TB relapse, 10% treatment after failure and 8.3% treatment after loss to follow-up. This study found that 65% of M. tuberculosis isolates were susceptible to rifampicin and isoniazid. Consequently, 35% of the isolates were resistant to rifampicin and/or isoniazid and 21.2% were multidrug-resistant (MDR). Treatment after failure [relative risk ratios (RRR) = 6.1, 95% CI: 1.691-22.011] and treatment after loss to follow-up (RRR = 7.115, 95% CI: 1.995-25.378) were significantly associated with MDR-TB. Unknown HIV status was significantly associated with isoniazid mono-resistance (RRR = 5.449, 95% CI: 1.054-28.184).

Conclusions

This study found that 65% of M. tuberculosis isolates were susceptible to rifampicin and isoniazid while 35% were resistant. Consequently, a high prevalence of MDR-TB is of public health concern. There is a need to heighten laboratory surveillance and early detection of drug-resistant TB to prevent the associated morbidity and mortality.

Drug susceptibility testing and line probe assay of first-line anti-tuberculosis drugs among presumptive tuberculosis patients attending a secondary care hospital in Bhubaneswar

Background

Pyrazinamide (PZA) is important for identification in multi-drug-resistant tuberculosis patients before starting therapy. PZA drug susceptibility testing (DST) is essential for the management of drug-resistant and susceptible TB patients.

Aims

The degree of drug resistance among TB patients and discrepancy between DST results of the phenotype and genotype were assessed.

Materials and Methods

Socio-demographic and clinical profiles of TB patients recruited in the study were documented. Sputum samples were processed for diagnosis using TrueNat Xpert MTB, TrueNat Xpert MTB Plus, and MGIT culture.

Results

Rifampicin (RIF) line probe assay (LPA) showed the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100%, whereas isoniazid (INH) LPA testing showed a sensitivity of 85.7%, a specificity and PPV of 100%, and NPV of 94.8%. The gene mutation for RIF resistance was between the codon, 530-533 of rpoB gene, and that for INH resistance was at the codon, 315 of katG gene.

Conclusion

Our findings demonstrated high prevalence of mono- and poly-drug resistance as well as pyrazinamide resistance.

Mutational analysis in drug resistant Mycobacterium tuberculosis in Western Uttar Pradesh

BACKGROUND

Multi-drug resistant tuberculosis (MDR-TB) results in treatment failure and poor clinical outcomes. This study was carried out with the aim to determine the pattern of drug resistance against Mycobacterium tuberculosis towards first line ATT (anti-tubercular treatment) in sputum smear-positive patients using Line Probe Assay (LPA).

METHODS

A cross sectional prospective study was carried out in a tertiary care Hospital of Meerut. A total of 898 sputum samples (on spot and early morning) collected from 449 suspected pulmonary tuberculosis patients as per RNTCP guidelines were screened by microscopy. Decontamination was done by N-acetyl-l-cysteine and sodium hydroxide. Then smear positive samples were subjected to 1st line drug susceptibility testing (DST) using LPA GenoType® MTBDRplus (HAIN Life Science) assay, a molecular method which allows rapid detection of Rifampicin (Rif) and Isoniazid (INH) resistance.

RESULTS

The overall burden of MDR TB in this geographical area was 7.9 %. Mono-resistance with Rif alone was around 2.8 %. However, the mono-resistance with INH (inhA gene) and INH (katG gene) was 2.8 % and 1.1 % respectively. Drug resistance of Rif was due to mutations in rpoB gene while resistances to INH were more commonly due to mutation in inhA gene followed by katG gene. TB was more commonly seen in the age group of 30-59 years (43.8 %) and predominantly in males.

CONCLUSION

Tuberculosis positivity rate is high in Western Uttar Pradesh. Burden of MDR TB in Western Uttar Pradesh was similar to National data. Line probe assay can be used as a primary method to diagnose multi drug resistant TB as done in present study which can help in earlier initiation of correct therapy.

Molecular characterization of genetic mutations with fitness loss in pulmonary tuberculosis patients associated with HIV co-infection in Northwest Amhara, Ethiopia

Objectives

Molecular approaches to identifying resistance-conferring mutations suggest a revolution in the field of tuberculosis. The aim of the study was to determine the association between resistance-conferring mutations with fitness loss in Mycobacterium tuberculosis clinical isolates and HIV co-infection in the Amhara region of Ethiopia.

Methods

A laboratory-based cross-sectional study was conducted between September 2022 and June 2023. A line probe assay was performed on 146 culture-positive clinical isolates. Logistic regression analysis was used to measure the strength of the association between the drug-resistance-conferring mutations with fitness loss in M. tuberculosis isolates and tuberculosis/HIV co-infection. A p-value ⩽ 0.05 was considered statistically significant.

Results

A total of 11 distinct mutations at four genetic loci among 19 resistant isolates were detected. The frequency of rifampicin, isoniazid, and fluoroquinolones resistance-conferring mutations was identified in 12 (8.2%), 17 (11.6%), and 2 (1.4%) of the isolates, respectively. The most prominent specific mutations were S450L (5/9, 55.6%), S315T (11/11, 100%), C-15T (4/4, 100%), and D94G (1/1, 100%). Double mutations were observed in 10 (52.6%) multidrug-resistant tuberculosis isolates; the most common were detected in both the rpoB and katG genes (8/10, 80.0%). The HIV-co-infected tuberculosis patients carried a higher proportion of low fitness of non-rpoB S450L variants than those tuberculosis patients without HIV (80.0% vs 14.3%) and showed a significant association (cOR = 0.042, 95% CI: 0.002-0.877, p = 0.041), but not with the low fitness of non-katG S315T variants (cOR = 3.00, 95% CI: 0.348-25.870, p = 0.318).

Conclusion

This study provides valuable information on the genetic variants with fitness loss associated with HIV co-infection, but requires further whole-genome-based mutation analysis.

Phenotypic and genotypic drug susceptibility patterns of Mycobacterium tuberculosis isolates from pulmonary tuberculosis patients in Central and Southern Ethiopia

INTRODUCTION

The persistence of tuberculosis (TB) infection in some patients after treatment has highlighted the importance of drug susceptibility testing (DST). This study aimed to determine the drug susceptibility patterns of Mycobacterium tuberculosis (M. tuberculosis) isolates from pulmonary TB (PTB) patients in Central and Southern Ethiopia.

METHODS

A health institution-based cross-sectional study was conducted between July 2021 and April 2022. Sputum samples were collected from newly diagnosed smear microscopy and/or Xpert MTB/RIF-positive PTB patients. The samples were processed and cultivated in Lowenstein-Jensen (LJ) pyruvate and glycerol medium. M. tuberculosis isolates were identified using polymerase chain reaction (PCR) based region of difference 9 (RD9) deletion typing. Phenotypic DST patterns of the isolates were characterized using the BACTEC MGIT™ 960 instrument with SIRE kit. Isoniazid (INH) and Rifampicin (RIF) resistant M. tuberculosis isolates were identified using the GenoType® MTBDRplus assay.

RESULTS

Sputum samples were collected from 350 PTB patients, 315 (90%) of which were culture-positive, and phenotypic and genotypic DST were determined for 266 and 261 isolates, respectively. Due to invalid results and missing data, 6% (16/266) of the isolates were excluded, while 94% (250/266) were included in the paired analysis. According to the findings, 14.4% (36/250) of the isolates tested positive for resistance to at least one anti-TB drug. Gene mutations were observed only in the rpoB and katG gene loci, indicating RIF and high-level INH resistance. The GenoType® MTBDRplus assay has a sensitivity of 42% and a specificity of 100% in detecting INH-resistant M. tuberculosis isolates, with a kappa value of 0.56 (95%CI: 0.36-0.76) compared to the BACTEC MGIT™ DST. The overall discordance between the two methods was 5.6% (14/250) for INH alone and 0% for RIF resistance and MDR-TB (resistance to both INH and RIF) detection.

CONCLUSION

This study reveals a higher prevalence of phenotypic and genotypic discordant INH-resistant M. tuberculosis isolates in the study area. The use of whole-genome sequencing (WGS) is essential for gaining a comprehensive understanding of these discrepancies within INH-resistant M. tuberculosis strains.

Characteristics of TB/HIV Co-Infection and Patterns of Multidrug-Resistance Tuberculosis in the Northwest Amhara, Ethiopia

Background

Multidrug-resistant tuberculosis (MDR-TB) has continued to be a serious public health threat and significantly challenges global TB control and prevention efforts, where the TB/HIV co-infection epidemic makes the situation much worse. The aim of the study was to determine the determinant factors associated with patterns of MDR-TB among pulmonary TB patients in the Northwest Amhara, Ethiopia.

Methods

A hospital-based cross-sectional study was conducted from May 2022 to February 2023 in the Northwest Amhara, Ethiopia. Data on the participants' socio-demographics and clinical characteristics were obtained using a pre-tested checklist. Phenotypic susceptibility testing to first-line anti-TB drugs was performed on 180 isolates by automated BD BACTEC MGIT 960 system. Logistic regression analysis was performed to determine the association of risk factors with patterns of MDR-TB. A p-value ≤0.05 was considered statistically significant.

Results

The overall proportion of TB with HIV co-infected cases was 19.8% (50/252). Culture positivity was confirmed in 203/252 (80.6%) of sputum samples. Among 168 isolates, the DST showed that 119 (70.8%) isolates were pan-susceptible to all first-line drugs and prevalence of any resistance to first-line drugs was 49,168 (29.2%). Among the resistant isolates, 28 (16.7%) were any mono-resistance and 12 (7.1%) were determined to be resistant to MDR-TB. TB with a previous TB treatment (aOR = 6.73, 95% CI: 1.78-25.47, p = 0.005) and HIV co-infected (aOR = 0.252, 95% CI: 0.73-0.875, p = 0.03) were significantly associated with MDR-TB.

Conclusion

Higher prevalence of TB and MDR-TB was examined among TB patients in the study area. In the study, history of previous TB treatment was the strongest risk factor MDR-TB infection followed by TB with HIV co-infected cases. Therefore, there is a need of strengthening TB control and prevention programs to reduce the increase of TB incidence, further emergence and transmission of a public health threat of MDR-TB cases.

Frequency of rpoB, katG, and inhA Gene Polymorphisms Associated with Multidrug-Resistant Mycobacterium tuberculosis Complex Isolates among Ethiopian TB Patients: A Systematic Review

Tuberculosis (TB) is one of the top 10 causes of mortality and the first killer among infectious diseases of poverty (IDoPs) worldwide. It disproportionately affects on-third of the world's low-income countries including Ethiopia. One of the factors driving the TB epidemic is the global rise of MDR/XDR-TB and their low detection affect the global TB control progress. Recently, the resistance-associated genetic mutations in MTBC known to confer drug resistance have been detected by rapid molecular diagnostic tests and sequencing methods. In this article, the published literature searched by PubMed database from 2010 to 2021 and English language were considered. The aim of this systematic review was to assess the prevalence of the most common rpoB, katG, and inhA gene mutations associated with multidrug resistance in MTBC clinical strains among TB patients in Ethiopia. Though 22 studies met our eligibility criteria, only 6 studies were included in the final analysis. Using the molecular GenoType MTBDRplus and MTBDRsl line probe assay and sequencing procedures, a total of 932 culture-positive MTBC isolates were examined to determine RIF, INH, and MDR-TB resistance patterns along with rpoB, katG, and inhA gene mutation analysis. As a result, among the genotypically tested MTBC isolates, 119 (12.77%), 83 (8.91%), and 73 (7.32%) isolates were INH, RIF, and MDR-TB resistant, respectively. In any RIF-resistant MTBC strains, the most common single point mutations were in codon 531 (S531L) followed by codon 526 (H526Y) of the rpoB gene. Besides, the most common mutations in any INH-resistant MTBC were strains observed at codon 315 (S315T) and WT probe in the katG gene and at codon C15T and WT1 probe in the inhA promoter region. Detection of resistance allele in rpoB, KatG, and inhA genes for RIF and INH could serve as a marker for MDR-TB strains. Tracking the most common S531L, S315T, and C15T mutations in rpoB, katG, and inhA genes among RIF- and INH-resistant isolates would be valuable in TB diagnostics and treatment regimens, and could reduce the development and risk of MDR/XDR-TB drug-resistance patterns.