Xpert MTB/XDR for detection of pulmonary tuberculosis and resistance to isoniazid, fluoroquinolones, ethionamide, and amikacin

Xpert MTB/XDR Assay for Detection of Resistance to Isoniazid, Fluoroquinolone, Aminoglycoside, and Ethionamide Among Patients with Pulmonary Tuberculosis in Bangladesh

INTRODUCTION

Early detection of drug resistance in patients with tuberculosis (TB) is crucial for prompt and effective treatment. This study evaluated the performance of Xpert MTB/XDR assay (Xpert XDR) for detecting resistance to isoniazid (INH), fluoroquinolones (FLQ), aminoglycosides (AMG), and ethionamide (ETH) in patients with pulmonary TB (PTB) in Bangladesh.

METHODS

Xpert XDR was performed on sputum samples from 793 Xpert MTB/RIF positive patients with PTB enrolled between April 2021 and March 2023. Results were compared with phenotypic drug susceptibility test (pDST) performed on Lowenstein-Jensen (L-J) media for the detection of resistance to INH, FLQ, AMG, and ETH. The performance of the assay was also compared between newly diagnosed or rifampicin (RIF)-sensitive versus re-treated or RIF-resistant patients with PTB.

RESULTS

Of 793 samples tested by Xpert XDR, indeterminate results for INH, FLQ, AMG, and ETH were observed for 3 (0.4%), 5 (0.6%), 33 (4.2%), and 0 (0%) isolates, respectively. The assay's sensitivity and specificity compared to pDST was 94.0% (95% CI 90.5-96.4; 264/281) and 97.3% (95% CI 95.4-98.5; 495/509), respectively for INH; 86.0% (95% CI 78.2-91.8; 98/114) and 99.3% (95% CI 98.3-99.3; 669/674), respectively for FLQ; 85.7% (95% CI 42.1-99.6; 6/7) and 99.9% (95% CI 99.3-100.0; 752/753), respectively for AMG; and 25.0% (95% CI 19.0-31.7; 48/192) and 96.7% (95% CI 94.9-98.0; 581/601), respectively for ETH. Agreement of Xpert XDR with pDST was almost perfect for detecting resistance to INH, FLQ, and AMG (kappa: 0.91, 0.89, and 0.86, respectively), but fair for ETH (kappa: 0.28). Xpert XDR performed significantly better among re-treated or RIF-resistant patients with TB compared to newly diagnosed or RIF-sensitive cases.

CONCLUSIONS

Given the high performance, Xpert XDR assay can be programmatically implemented nationwide for rapid and accurate detection of resistance to INH, FLQ, and AMG in patients with PTB, aiding clinicians in selecting appropriate regimens for the treatment of drug-resistant TB.

Truenat MTB assays for pulmonary tuberculosis and rifampicin resistance in adults and adolescents

BACKGROUND

Accurate and rapid diagnosis is crucial for ending the tuberculosis epidemic. Truenat assays are World Health Organization (WHO)-recommended rapid molecular diagnostic tests that detect Mycobacterium tuberculosis complex and rifampicin resistance.

OBJECTIVES

Primary objective To assess the diagnostic accuracy of Truenat assays (MTB, MTB Plus, and MTB-RIF Dx) for detecting pulmonary tuberculosis and rifampicin resistance in adults and adolescents with presumptive pulmonary tuberculosis. Secondary objectives To compare the diagnostic accuracy of Truenat assays and Xpert MTB/RIF Ultra for detecting pulmonary tuberculosis and rifampicin resistance and to investigate potential sources of heterogeneity (e.g. HIV status and smear status).

SEARCH METHODS

We searched MEDLINE, Embase, Science Citation Index and Biosis previews, Global Index Medicus, SCOPUS, WHO ICTRP, and ClinicalTrials.gov for published articles and trials in progress on 16and 17 October 2023. We searched ProQuest Dissertations & Theses A&I for dissertations. We contacted tuberculosis experts for ongoing and unpublished studies. A WHO public call for data was made between 30 November 2023 and 15 February 2024.

SELECTION CRITERIA

We included cross-sectional and cohort studies that evaluated Truenat assays in sputum samples from adolescents and adults (aged 10 years and older). The microbiological reference standard for identifying pulmonary tuberculosis is culture. The reference standard for rifampicin resistance is a culture-based drug susceptibility test. Two review authors independently screened titles and abstracts, and assessed the full texts of potentially eligible articles. A third review author resolved any disagreements.

DATA COLLECTION AND ANALYSIS

We tailored and applied the QUADAS-2 and QUADAS-C tools to assess the risk of bias and applicability. Two review authors independently extracted data for each included study, and a third review author resolved any disagreements. We performed meta-analyses to estimate summary sensitivities and specificities using a bivariate model. We assessed the certainty of evidence using the GRADEpro GDT tool.

MAIN RESULTS

Of nine eligible articles, one contributed two distinct participant cohorts, which we considered as separate studies. Thus, we included 10 studies; three assessed Xpert Ultra. Most studies were set in low- and middle-income countries with a high tuberculosis burden. Six studies (4081 participants, 1379 with tuberculosis) assessed Truenat MTB, and four studies (3073 participants, 750 with tuberculosis) assessed Truenat MTB Plus. Two studies (966 participants, 111 with rifampicin resistance) assessed Truenat MTB-RIF Dx. Overall, the risk of bias in the included studies was low. Three of the 10 studies were judged to have high applicability concern in the patient selection domain. Detection of pulmonary tuberculosis The summary sensitivity of Truenat MTB was 87.6% (95% confidence interval (CI) 81.6 to 91.8; high-certainty evidence), and the summary specificity was 86.1% (95% CI 70.1 to 94.3; moderate-certainty evidence). For Truenat MTB Plus, the summary sensitivity was 90.6% (95% CI 83.7 to 94.8; high-certainty evidence), and the summary specificity was 95.7% (95% CI 94.7 to 96.5; high-certainty evidence). Based on the three comparative studies, the summary sensitivity of Truenat MTB was lower (81.0%, 95% CI 72.8 to 87.2) than that of Xpert Ultra (93.7%, 95% CI 90.4 to 95.9), while the summary specificity of Truenat MTB (97.0%, 95% CI 91.9 to 98.9) was marginally higher than Xpert Ultra (95.3%, 95% CI 90.9 to 97.7). Detection of rifampicin resistance The sensitivities from the two studies were 53% and 85% (moderate-certainty evidence) and specificities were both 97% (high-certainty evidence).

AUTHORS' CONCLUSIONS

Truenat MTB Plus had higher sensitivity and specificity than Truenat MTB. The high false-positive rate for Truenat MTB is a concern. The sensitivity of Xpert Ultra was significantly higher than that of Truenat MTB, while specificity was slightly lower. Evidence on the accuracy of Truenat MTB-RIF Dx was limited.

Characteristics and risk factors of pulmonary fungal infection in patients with pulmonary tuberculosis

OBJECTIVE

To investigate the characteristics of and the risk factors for pulmonary fungal infection in patients with pulmonary tuberculosis (PT).

METHODS

A retrospective analysis was conducted on the clinical data of 218 PT patients treated at Beijing Luhe Hospital Affiliated with Capital Medical University from May 2022 to May 2024. Based on the presence or absence of fungal infection, these 218 patients were assigned to an infection group (n=87) or a non-infection group (n=131). Clinical baseline data, pulmonary fungal infection status ten days after admission, clinical symptoms on the first day of admission, and serum protein and hemoglobin levels were compared between the two groups. Logistic regression analysis was conducted to identify independent risk factors for pulmonary fungal infection in PT patients. A receiver operating characteristic (ROC) curve was generated to evaluate the predictive performance of these independent risk factors.

RESULTS

Among the 218 PT patients included, 87 (39.91%) had fungal infections. A total of 210 fungal strains were isolated and cultured from the infection group, with Candida albicans accounting for the highest proportion (42.65%), followed by candida tropicalis (20.59%) and Candida glabrata (17.65%). The infection group exhibited significantly higher rates of cough, fever, anemia, and pulmonary rales compared to the non-infection group (all P<0.05). The infection group showed significantly lower levels of serum protein and hemoglobin than the non-infection group (P<0.0001). Multivariate analysis identified history of smoking, disease course, duration of corticosteroid use, invasive procedure, serum protein level, and hemoglobin level as independent factors for fungal infection in PT patients. ROC curve analysis indicated that serum protein levels had the highest accuracy and area under the curve (AUC) value, while smoking history and hemoglobin levels performed less well in the model.

CONCLUSION

This study found a high rate of pulmonary fungal infections among PT patients, with Candida albicans being the most prevalent, followed by candida tropicalis and Candida glabrata. A history of smoking, a prolonged disease course, invasive procedures, extended corticosteroid use, and low serum protein and hemoglobin levels are independent factors for fungal infection in PT patients.

Whole genomic analysis uncovers high genetic diversity of rifampicin-resistant Mycobacterium tuberculosis strains in Botswana

Background

The emergence of drug-resistant Mycobacterium tuberculosis (M. tb) strains remains a threat to tuberculosis (TB) prevention and care. Understanding the drug resistance profiles of circulating strains is crucial for effective TB control. This study aimed to describe the genetic diversity of rifampicin-resistant M. tb strains circulating in Botswana using whole genome sequencing (WGS).

Methods

This study included 202 stored M. tb isolates from people diagnosed with rifampicin-resistant TB (RR-TB) between January 2016 and June 2023. Genomic DNA was extracted using the cetyltrimethylammonium bromide (CTAB) method. Library preparation was performed using the Illumina DNA prep kit following the manufacturer's instructions. Sequencing was done on Illumina NextSeq2000. TBProfiler software was used to identify known M. tb lineages and drug resistance profiles. Statistical analyses were performed on STATA version 18.

Results

WGS analysis revealed multidrug resistance (57.9%: 95% CI; 50.7-64.8), Pre-XDR (16.8%, 95% CI: 11.9-22.7), RR-TB (20.2%: 95% CI: 14.98-26.5), and HR-TB (0.5%, 95% CI; 0.01-2.7). We identified a high genetic diversity with three predominant lineages: lineage 4 (60.9%, 95% CI; 53.8-67.7), lineage 1 (22.8%: 95% CI; 17.2-29.2), and lineage 2 (13.9%, 95% CI: 9.4-19.4). The most frequently observed drug resistance mutations for rifampicin, isoniazid, ethambutol, streptomycin, pyrazinamide, and fluoroquinolones were rpoB S450L (28.6%), katG S315T (60.5%), embA_c.-29_-28delCT, embB Q497R (31.7%), rrs_n.517C>T (47.1%), pncA_c.375_389delCGATGAGGTCGATGT (36.0%) and gyrA A90V (79.4%), respectively. No bedaquiline and delamanid resistance-associated mutations were detected.

Conclusions

This study highlights the high genetic diversity of M. tb strains, with a predominance of lineage 4 among people with RR-TB in Botswana. It provides valuable insights into the genetic diversity of rifampicin-resistant M. tb strains circulating in Botswana.

Tuberculosis Diagnosis and Management: Recent Advances

Accurate and rapid diagnosis is crucial for starting effective treatment for tuberculosis (TB) and mitigating the transmission. Globally, nearly one-third of all TB cases remain undetected each year and consequently these are not reported. On top of that, the emergence of drug-resistant TB poses an added challenge. In the past 15 years, several advances have been made for improved diagnosis, including liquid culture and drug susceptibility, line probe assay for drug resistance detection, and cartridge-based nucleic acid amplification tests for rapid diagnosis of TB and drug resistance detection. However, some challenges remain, despite the clear edge of these new advances over the age-old conventional methods. Despite these advances, accurate, affordable, and accessible diagnosis of TB remains a challenge, especially in rural and difficult-to-reach settings, where the most desirable test would be a point-of-care triage test. Nevertheless, several attempts are being made in this direction, and in this article, we review these research advances that can help the TB elimination from India.

Impact of isoniazid monoresistance on overall and vulnerable patient populations in Taiwan

Isoniazid is an early bactericidal anti-tuberculosis (TB) agent and isoniazid mono-resistance TB is the most prevalent drug-resistant TB worldwide. Concerns exist regarding whether resistance to isoniazid would lead to delayed culture conversion and worst outcomes. From January 2008 to November 2017, adult culture-positive pulmonary TB patients receiving isoniazid, rifampicin, pyrazinamide, and ethambutol were identified through Taiwan Center for Disease Control database and were followed until the end of 2017. Primary outcomes included time to sputum culture conversion (SCC) within two months. Secondary outcomes included death and unfavourable outcomes at the end of 2nd month. A total of 37,193 drug-susceptible and 2,832 isoniazid monoresistant pulmonary TB patients were identified. Compared with no resistance, isoniazid monoresistance was not associated with a delayed SCC (HR: 0.99, 95% CI: 0.94─1.05, p = 0.8145), a higher risk of 2-month mortality (HR: 1.19, 95% CI: 0.92─1.53, p = 0.1884), and unfavourable outcomes at 2nd month (OR: 1.05, 95% CI: 0.97─1.14, p = 0.2427). Isoniazid monoresistance was associated with delayed SCC (HR: 0.90, 95% CI: 0.83─0.98, p = 0.0099) and a higher risk of unfavourable outcomes (OR:1.18, 95% CI: 1.05─1.32, p = 0.0053) in patients aged between 20 and 65, and delayed SCC in patients without underlying comorbidities (HR: 0.90, 95% CI: 0.81─0.98, p = 0.0237). Isoniazid mono-resistant TB had a comparable outcome with drug-susceptible TB at the end of the intensive phase. Healthy, and non-elderly patients were more likely to had culture persistence, raising concerns about disease transmission in these subgroups and warranting early molecular testing for isoniazid resistance.

Xpert MTB/XDR assay: rapid TB drug resistance detection

PURPOSE

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.

METHODS

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.

RESULTS

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%).

CONCLUSIONS

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.

Pulmonary tuberculosis in non-HIV adults: an evergreen old-fashioned disease in high-income countries. A narrative review

INTRODUCTION

Tuberculosis (TB), an infective air-borne disease with worldwide non-homogeneous distribution, remains a top cause of morbidity and mortality. TB control is linked to early diagnosis and proper treatment of contagious TB cases and infected subjects at high risk of developing TB.

AREAS COVERED

A narrative review of pulmonary TB in non-HIV adults with reference to high-income countries. Modern medicine offers several advancements in diagnostics and therapeutics of TB, but they often remain to be extensively implemented in real life. In high-income countries TB is now relatively uncommon, but it remains a health and socio-economic burden that should not be underestimated.

EXPERT OPINION

Pulmonologists should maintain expertise toward TB for several reasons. First, the lung is the most common and the infectious moiety of TB. Second, TB remains a global issue due to common travels of western people and migrations from areas with high incidence of TB. Third, as TB has heterogenous clinics, its prompt diagnosis may be difficult. Fourth, TB is a curable disease, but its management is complex and predisposes to poor adherence with failures/relapses and selection of drug-resistant strains.

Diagnostic accuracy of LiquidArray MTB-XDR VER1.0 for the detection of Mycobacterium tuberculosis complex, fluoroquinolone, amikacin, ethambutol, and linezolid susceptibility

Drug susceptibility testing (DST) is essential for effectively starting people on effective tuberculosis (TB) regimens. No accuracy data exists for the new high-throughput LiquidArray MTB-XDR (LA-XDR) test, which detects Mycobacterium tuberculosis complex (MTBC) and susceptibility to the fluoroquinolones, amikacin, ethambutol, and linezolid (the latter two drugs have no rapid molecular DSTs available). We enrolled (n=720) people with presumptive TB who provided two sputa for Xpert MTB/RIF Ultra and culture (MTBC reference standard). Phenotypic DST and Sanger sequencing served as a composite reference standard. Manual FluoroLyse and automated GenoXtract-fleXT (fleXT) DNA extraction methods were compared. For MTBC, LA-XDR using fleXT-extracted or FluoroLyse-extracted DNA had similar sensitivities (85-87%; which improved upon eluate retesting) and specificities (99%). Drug susceptibility sensitivities varied: 94% (86, 98) for fluoroquinolones, 64% (45, 80) for amikacin, and 88% (79, 93) for ethambutol (specificities 97-100%). LA-XDR detected 86% (6/7) phenotypically resistant linezolid isolates. LA-XDR with fleXT had indeterminate proportions of 8% (21/251) for fluoroquinolones, 1% (2/251) for ethambutol, 25% (63/251) for amikacin, and 37% (93/251) for linezolid. In a hypothetical population of 100 smear-negative fluoroquinolones-resistant cases, 24% (24/100) could be missed due to an unsuccessful result (1 fleXT error and, for LA-XDR, 2 invalid results, 15 MTBC-negative, 6 fluoroquinolone-indeterminate, 1 false-susceptible). LA-XDR met the minimum WHO target product profile for a next-generation sputum-based moderate complexity DST with high sensitivity for fluoroquinolones and ethambutol resistance, moderate sensitivity for amikacin resistance, and promise for linezolid resistance, for which more data are needed. Improved MTBC detection would reduce missed resistance.

Reflex Xpert MTB/XDR Testing of Residual Rifampicin-Resistant Specimens: A Clinical Laboratory-Based Diagnostic Accuracy and Feasibility Study in South Africa

Background

The World Health Organization-approved Xpert MTB/XDR test detects Mycobacterium tuberculosis and resistance to isoniazid, fluoroquinolones, ethionamide, and injectable drugs directly in specimens. This pragmatic, laboratory-based study assessed the diagnostic accuracy and feasibility of a reflex testing approach, where Xpert MTB/XDR was performed on residual specimens previously processed for Xpert MTB/RIF Ultra.

Methods

Routine respiratory specimens, processed for Xpert MTB/RIF Ultra, were stored in sample reagent buffer at 2°C-8°C. If rifampicin resistant, the residual specimen was assessed for adequate volume (≥2 mL) and tested with Xpert MTB/XDR, with storage time recorded. A second specimen was used for routine and reference standard testing (culture and sequencing).

Results

Specimens (99% sputum) from 763 participants submitted to 2 large routine laboratories were included. Xpert MTB/XDR yielded valid resistance detection results in 639 (84%), compared with 507 (66%) for routine testing (difference [95% CI], 18% [13%-22%]). The median turnaround time for results was 23 hours for Xpert MTB/XDR and 15 days for routine testing. While 748 specimens (98%) were ≥2 mL, only 102 (13%) were stored for ≤4 hours. By the reference standard, 284 of 394 (72%) were isoniazid resistant, and 57 of 380 (15%) were fluroquinolone resistant. The sensitivities of Xpert MTB/XDR were 94% (95% CI, 91%-97%) for isoniazid and 91% (81%-97%) for fluoroquinolone resistance detection. The specificities were 98% (94%-100%) and 100% (98%-100%), respectively.

Conclusions

Xpert MTB/XDR performed favorably compared with the reference, and the reflex testing approach increased results availability over routine testing, while dramatically decreasing turnaround time from weeks to hours. Laboratory workflow precluded testing within the manufacturer-recommended 4-hour storage time, but longer storage did not appear detrimental.

ISCCM Position Statement on the Approach to and Management of Critically Ill Patients with Tuberculosis

Tuberculosis (TB) is an important cause of morbidity and mortality globally. About 3-4% of hospitalized TB patients require admission to the intensive care unit (ICU); the mortality in these patients is around 50-60%. There is limited literature on the evaluation and management of patients with TB who required ICU admission. The Indian Society of Critical Care Medicine (ISCCM) constituted a working group to develop a position paper that provides recommendations on the various aspects of TB in the ICU setting based on available evidence. Seven domains were identified including the categorization of TB in the critically ill, diagnostic workup, drug therapy, TB in the immunocompromised host, organ support, infection control, and post-TB sequelae. Forty-one questions pertaining to these domains were identified and evidence-based position statements were generated, where available, keeping in focus the critical care aspects. Where evidence was not available, the recommendations were based on consensus. This position paper guides the approach to and management of critically ill patients with TB.

How to cite this article

Chacko B, Chaudhry D, Peter JV, Khilnani G, Saxena P, Sehgal IS, et al. isccm Position Statement on the Approach to and Management of Critically Ill Patients with Tuberculosis. Indian J Crit Care Med 2024;28(S2):S67-S91.

Evaluation of Diagnostic Methods and Rifampicin Resistance in Pulmonary Tuberculosis: A Hospital-Based Study

Background Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis, predominantly affecting the lungs (pulmonary TB) and is a significant public health challenge in India. The study aims to analyze demographic, radiological, and clinical subgroups of pulmonary TB cases, examine the relationship between smear acid-fast bacillus (AFB examination) and cartridge-based nucleic acid amplification test (CBNAAT), evaluate CBNAAT sensitivity for Mycobacterium tuberculosis (MTB) in new and previously treated patients, and determine the proportion of rifampicin resistance. Methods This hospital-based prospective study was conducted among patients diagnosed with pulmonary TB at the Respiratory Medicine Department of a Government Hospital over 16 months (August 2019 to December 2020). The study included 150 diagnosed TB cases (new and previously treated). Data collection encompassed demographic details, clinical symptoms, comorbidities, radiological findings (chest X-ray), and microbiological results (smear AFB examination, CBNAAT). Sputum samples were subjected to Ziehl-Neelsen staining and CBNAAT for MTB detection and rifampicin resistance testing. Statistical analysis was performed using IBM SPSS Statistics version 21.0 (IBM Corp., Armonk, NY, USA). Results Of the 150 patients, 69.3% were male, and 48% were aged 21-40 years. The majority had a BMI of 18.5-24.9 kg/m² (50%) and resided in urban areas (63.3%). Common symptoms included cough (95.3%), fever (80%), and weight loss (74%). Cavitary lesions on chest X-ray were observed in 84% of patients. Smear microscopy detected MTB in 72.7% of cases, while CBNAAT detected MTB in 94% of cases. CBNAAT sensitivity for smear-positive and smear-negative samples was 93.97% and 94.12%, respectively. Rifampicin resistance was found in 3% of new cases and 6% of previously treated cases. The sensitivity of smear microscopy was 77.33%, and the sensitivity of CBNAAT was 94%. Conclusion The study underscores the high burden of pulmonary TB and the utility of CBNAAT in detecting MTB and rifampicin resistance, particularly in smear-negative samples. The findings highlight the necessity of universal drug susceptibility testing (DST) for effective TB management and the importance of addressing drug resistance to improve treatment outcomes.

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

INTRODUCTION

Early 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.

METHODS

We 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.

FINDINGS

We 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%.

CONCLUSION

The 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.

What is New in the Diagnosis of Childhood Tuberculosis?

The fact that almost half of the 1 million cases of childhood tuberculosis (TB) globally remain undiagnosed jeopardizes the TB elimination goal. Fortunately, there are new advances in this field which have the potential to bridge this diagnostic gap. Advances in imaging include computer assisted interpretation of chest X-rays (CXRs), point of care ultrasound (POCUS) and faster and superior computed tomography/ magnetic resonance imaging (CT/ MRI) protocols. The urine lipoarabinomannan test has proved to be a good point of care test for diagnosing TB in Human immunodeficiency virus (HIV) infected children. Stool and nasopharyngeal aspirates are emerging as acceptable alternatives for gastric lavage and induced sputum for diagnosing intrathoracic tuberculosis. Xpert MTB/RIF Ultra has improved sensitivity compared to Xpert MTB/RIF for diagnosing both pulmonary/ extrapulmonary TB. Xpert XDR is another commercially available accurate point of care test for detecting resistance to drugs other than rifampicin in smear positive samples. Other molecular methods including new line probe assays, pyrosequencing, whole genome sequencing, and targeted next generation sequencing are extremely promising but not available commercially at present. The C-Tb skin test is an acceptable alternative to the tuberculin skin test and interferon gamma release assays for diagnosis of latent infection. There is an urgent need to incorporate some of these advances in the existing diagnostic algorithms of childhood TB.

Carrimycin in the treatment of acute promyelocytic leukemia combined with pulmonary tuberculosis: A case report

BACKGROUND

Pulmonary tuberculosis (PTB) is prevalent in immunocompromised populations, including patients with hematologic malignancies, human immunodeficiency virus infections, and chronic diseases. Effective treatment for acute promyelocytic leukemia (APL) combined with PTB is lacking. These patients show an extremely poor prognosis. Therefore, studies should establish efficient treatment options to improve patient survival and prognosis.

CASE SUMMARY

A 60-year-old male with pain in the right side of his chest and a fever for 4 d visited the outpatient department of our hospital. Peripheral blood smear revealed 54% blasts. Following bone marrow examinations, variant APL with TNRC18-RARA fusion gene was diagnosed. Chest computed tomography scan showed bilateral pneumonitis with bilateral pleural effusions, partial atelectasis in the lower lobes of both lungs, and the bronchoalveolar lavage fluid gene X-Pert test was positive, indicative of PTB. Carrimycin, ethambutol (EMB), and isoniazid (INH) were administered since he could not receive chemotherapy as the WBC count decreased continuously. After one week of treatment with carrimycin, the patient recovered from fever and received chemotherapy. Chemotherapy was very effective and his white blood cells counts got back to normal. After being given five months with rifampin, EMB and INH and chemotherapy, the patient showed complete remission from pneumonia and APL.

CONCLUSION

We report a case of PTB treated successfully with carrimycin with APL that requires chemotherapy.

Direct Detection of Fluoroquinolone Resistance in Sputum Samples from Tuberculosis Patients by High Resolution Melt Curve Analysis

Multidrug-resistant tuberculosis (MDR-TB) requires treatment with fluoroquinolone (FLQ) drugs, however, the excessive use of FLQ has led to the rise of extensively drug-resistant TB. In 2019, ~ 20% of total MDR-TB cases were estimated to be resistant to FLQ drugs. In the present study, we developed and evaluated the utility of high-resolution melt curve analysis (HRM) for the rapid detection of FLQ-resistant Mycobacterium tuberculosis for the first time directly from sputum samples. A reference plasmid library was generated for the most frequently observed mutations of gyrA gene and was used to discriminate between mutant and wild-type samples in the FLQ-HRM assay. The developed assay was evaluated on n = 25 MDR M. tuberculosis clinical isolates followed by validation on archived sputum DNA (n = 88) using DNA sequencing as a gold standard. The FLQ-HRM assay showed a 100% sensitivity [95% Confidence Interval (CI): 71.5 to 100] and specificity (95% CI: 39.7 to 100) in smear-positive category, and a sensitivity of 88.9% (95% CI: 77.3 to 95.8) with 84.2% (95% CI: 60.4 to 96.6) specificity in smear-negative category. The assay showed a high level of concordance of ~ 90% (κ = 0.74) with DNA sequencing, however, we were limited by the absence of phenotypic drug susceptibility testing data. In conclusion, HRM is a rapid, cost-effective (INR 150/USD 1.83) and closed-tube method for direct detection of FLQ resistance in sputum samples including direct smear-negative samples.

Genetic overlap for ten cardiovascular diseases: A comprehensive gene-centric pleiotropic association analysis and Mendelian randomization study

Recent studies suggest that pleiotropic effects may explain the genetic architecture of cardiovascular diseases (CVDs). We conducted a comprehensive gene-centric pleiotropic association analysis for ten CVDs using genome-wide association study (GWAS) summary statistics to identify pleiotropic genes and pathways that may underlie multiple CVDs. We found shared genetic mechanisms underlying the pathophysiology of CVDs, with over two-thirds of the diseases exhibiting common genes and single-nucleotide polymorphisms (SNPs). Significant positive genetic correlations were observed in more than half of paired CVDs. Additionally, we investigated the pleiotropic genes shared between different CVDs, as well as their functional pathways and distribution in different tissues. Moreover, six hub genes, including ALDH2, XPO1, HSPA1L, ESR2, WDR12, and RAB1A, as well as 26 targeted potential drugs, were identified. Our study provides further evidence for the pleiotropic effects of genetic variants on CVDs and highlights the importance of considering pleiotropy in genetic association studies.

To Test or Not? Xpert MTB/RIF as an Alternative to Smear Microscopy to Guide Line Probe Assay Testing for Drug-Resistant Tuberculosis

Xpert MTB/RIF (Xpert) revolutionized tuberculosis (TB) diagnosis. Laboratory decision making on whether widely-used reflex drug susceptibility assays (MTBDRplus, first-line resistance; MTBDRsl, second-line) are conducted is based on smear status, with smear-negative specimens often excluded. We performed receiver operator characteristic (ROC) curve analyses using bacterial load information (smear microscopy grade, Xpert-generated semi-quantitation categories and minimum cycle threshold [CTmin] values) from Xpert rifampicin-resistant sputum for the prediction of downstream line probe assay results as "likely non-actionable" (no resistance or susceptible results generated). We evaluated actionable-to-non-actionable result ratios and pay-offs with missed resistance versus LPAs done universally. Smear-negatives were more likely than smear-positive specimens to generate a non-actionable MTBDRplus (23% [133/559] versus 4% [15/381]) or MTBDRsl (39% [220/559] versus 12% [47/381]) result. However, excluding smear-negatives would result in missed rapid diagnoses (e.g., only 49% [264/537] of LPA-diagnosable isoniazid resistance would be detected if smear-negatives were omitted). Testing smear-negatives with a semi-quantitation category ≥ "medium" had a high ratio of actionable-to-non-actionable results (12.8 or a 4-fold improvement versus testing all using MTBDRplus, 4.5 or 3-fold improvement for MTBDRsl), which would still capture 64% (168/264) and 77% (34/44) of LPA-detectable smear-negative resistance, respectively. Use of CTmins permitted optimization of this ratio with higher specificity for non-actionable results but decreased resistance detected. Xpert quantitative information permits identification of a smear-negative subset in whom the payoffs of the ratio of actionable-to-non-actionable LPA results with missed resistance may prove acceptable to laboratories, depending on context. Our findings permit the rational expansion of direct DST to certain smear-negative sputum specimens.

Rolling out new anti-tuberculosis drugs without diagnostic capacity

Deaths from tuberculosis (TB) reached over 1.6 million in 2021 with 10.6 million people becoming ill. Multidrug-resistant TB, defined as the Mycobacterium tuberculosis organism having resistance to at least isoniazid and rifampicin, represented 3.9% of new TB cases and 18% of previously treated cases. While new drug regimens continue to be developed and introduced to improve treatment of drug-resistant forms of TB, diagnostic capability to identify drug resistance lags woefully behind. While significant mortality benefits exist for these newer drug regimens, implementing them without proper drug resistance diagnostic capacity could lead to development of more drug resistances and exhaust these new therapeutic tools. Moving forward, the roll-out of new TB drugs and regimens must be paired with implementation of diagnostics to ensure judicious use of resources and the best chance for improving TB worldwide.

Metabolomic analysis of Mycobacterium tuberculosis reveals metabolic profiles for identification of drug-resistant tuberculosis

The detection of pre-extensively (pre-XDR) and extensively drug-resistant tuberculosis (XDR-TB) is challenging. Drug-susceptibility tests for some anti-TB drugs, especially ethambutol (ETH) and ethionamide (ETO), are problematic due to overlapping thresholds to differentiate between susceptible and resistant phenotypes. We aimed to identify possible metabolomic markers to detect Mycobacterium tuberculosis (Mtb) strains causing pre-XDR and XDR-TB. The metabolic patterns of ETH- and ETO-resistant Mtb isolates were also investigated. Metabolomics of 150 Mtb isolates (54 pre-XDR, 63 XDR-TB and 33 pan-susceptible; pan-S) were investigated. Metabolomics of ETH and ETO phenotypically resistant subgroups were analyzed using UHPLC-ESI-QTOF-MS/MS. Orthogonal partial least-squares discriminant analysis revealed distinct separation in all pairwise comparisons among groups. Two metabolites (meso-hydroxyheme and itaconic anhydride) were able to differentiate the pre-XDR and XDR-TB groups from the pan-S group with 100% sensitivity and 100% specificity. In comparisons of the ETH and ETO phenotypically resistant subsets, sets of increased (ETH = 15, ETO = 7) and decreased (ETH = 1, ETO = 6) metabolites specific for the resistance phenotype of each drug were found. We demonstrated the potential for metabolomics of Mtb to differentiate among types of DR-TB as well as between isolates that were phenotypically resistant to ETO and ETH. Thus, metabolomics might be further applied for DR-TB diagnosis and patient management.

Evaluation of Xpert ® MTB/XDR test for susceptibility testing of Mycobacterium tuberculosis to first and second-line drugs in Uganda

Background

Drug-Resistant Tuberculosis (DR-TB) is one of the key challenges toward TB control. There is an urgent need for rapid and accurate drug susceptibility tests (DST) for the most commonly used 1 st and 2 nd line TB drugs.

Design and Methods

In a blinded, laboratory-based cross-sectional study, we set out to validate the performance of the Xpert ® MTB/XDR test for DST of M. tuberculosis . Sputum samples or culture isolates collected between January 2020 and December 2021 from patients with rifampicin resistance -TB and/or with higher suspicion index for isoniazid (INH) resistance and/or 2 nd line fluoroquinolones (FQ) and injectable agents (IAs) were tested using the Xpert ® MTB/XDR test from 11/September 2021 to 26/May /2022. Diagnostic accuracy and factors for laboratory uptake of Xpert ® MTB/XDR test were compared to MGIT960 and the Hain Genotype® MTBDR plus and MDRsl assays (LPA) as reference DST methods.

Results

A total of 100 stored sputum samples were included in this study. Of the samples tested using MGIT960, 65/99 (65.6%) were resistant to INH, 5/100 (5.0%) resistant to FQ and none were resistant to IAs. The sensitivity and specificity, n (%; 95%Confidence Interval, CI) of Xpert ® MTB/XDR test for; INH were 58 (89.2; 79.1-95.5) and 30 (88.2; 72.5-96.6), FQ; 4 (80.0; 28.3-99.4) and 95 (100; 96.2-100), respectively. The specificity for AIs was 100 (100; 96.3-100). Using LPA as a reference standard, a total of 52/98 (53.1%) were resistant to INH, 3/100 (3.0%) to FQ, and none to IA. The sensitivity and specificity, n (%; 95%CI) of Xpert ® MTB/XDR test compared to LPA for; INH was 50 (96.1; 86.7-99.5) and 34 (74.0; 58.8-85.7) and FQ 3 (100; 29.2-100) and 96 (99.0; 94.3-99.9) respectively. The specificity of IAs was 96 (100; 96.2-100). The factors for laboratory uptake and roll-out included; no training needed for technicians with previous Xpert-ultra experience and one day for those without, recording and reporting needs were not different from those of Xpert ultra, the error rate was 4/100 (4%), no uninterpretable results reported, test turn-around-time was 1hr/45 minutes and workflow similar to that of the Xpert-ultra test.

Conclusion

There is high sensitivity and specificity of Xpert ® MTB/XDR test for isoniazid, fluoroquinolones, and Injectable agents. There are acceptable Xpert ® MTB/XDR test attributes for test uptake and roll-out.

Antibiotic therapy for pan-drug-resistant infections

Antibiotic resistance occurs when microorganisms resist the drugs used against the infection caused by them and neutralize their effects over time using various mechanisms. These mechanisms include preventing drug absorption, changing drug targets, drug inactivating, and using efflux pumps, which ultimately cause drug resistance, which is named pan-drug-resistant (PDR) infection if it is resistant to all antimicrobial agents. This type of drug resistance causes many problems in society and faces the health system with difficulties; therefore their treatment is crucial and encourages doctors to develop new drugs to treat them. PDR Gram-negative bacteria, including Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli are among the most significant resistant bacteria to many antimicrobial agents, and only a limited range of antibiotics, especially synergistically are effective on them. For the therapy of PDR A. baumannii, tigecycline in combination with colestimethate, imipenem, amikacin, and ampicillin-sulbactam are the most effective treatments. The utilization of β-lactamase inhibitors such as ceftolozane-tazobactam, ceftazidime-avibactam, or imipenem-cilastatin-relebactam has the most efficacy against PDR P. aeruginosa. The PDR K. pneumoniae has been treated in the last decades with tigecycline and colistin, but currently, nitrofurantoin, fosfomycin, and pivmecillinam seem to be the most effective agent for the therapy of PDR E. coli. While these drugs impressively struggle with PDR pathogens, due to the daily increase in antibiotic resistance in microorganisms worldwide, there is still an urgent need for the expansion of novel medicines and methods of combating resistance.

Mycobacterium tuberculosis Transmission in High-Incidence Settings-New Paradigms and Insights

Tuberculosis has affected humankind for thousands of years, but a deeper understanding of its cause and transmission only arose after Robert Koch discovered Mycobacterium tuberculosis in 1882. Valuable insight has been gained since, but the accumulation of knowledge has been frustratingly slow and incomplete for a pathogen that remains the number one infectious disease killer on the planet. Contrast that to the rapid progress that has been made in our understanding SARS-CoV-2 (the cause of COVID-19) aerobiology and transmission. In this Review, we discuss important historical and contemporary insights into M. tuberculosis transmission. Historical insights describing the principles of aerosol transmission, as well as relevant pathogen, host and environment factors are described. Furthermore, novel insights into asymptomatic and subclinical tuberculosis, and the potential role this may play in population-level transmission is discussed. Progress towards understanding the full spectrum of M. tuberculosis transmission in high-burden settings has been hampered by sub-optimal diagnostic tools, limited basic science exploration and inadequate study designs. We propose that, as a tuberculosis field, we must learn from and capitalize on the novel insights and methods that have been developed to investigate SARS-CoV-2 transmission to limit ongoing tuberculosis transmission, which sustains the global pandemic.

Mycobacterium tuberculosis Drug Resistance in Ethiopia: An Updated Systematic Review and Meta-Analysis

Background: Tuberculosis (TB) remains a significant global public health issue, despite advances in diagnostic technologies, substantial global efforts, and the availability of effective chemotherapies. Mycobacterium tuberculosis, a species of pathogenic bacteria resistant to currently available anti-TB drugs, is on the rise, threatening national and international TB-control efforts. This systematic review and meta-analysis aims to estimate the pooled prevalence of drug-resistant TB (DR-TB) in Ethiopia. Materialsand Methods: A systematic literature search was undertaken using PubMed/MEDLINE, HINARI, the Web of Science, ScienceDirect electronic databases, and Google Scholar (1 January 2011 to 30 November 2020). After cleaning and sorting the records, the data were analyzed using STATA 11. The study outcomes revealed the weighted pooled prevalence of any anti-tuberculosis drug resistance, any isoniazid (INH) and rifampicin (RIF) resistance, monoresistance to INH and RIF, and multidrug-resistant TB (MDR-TB) in newly diagnosed and previously treated patients with TB. Results: A total of 24 studies with 18,908 patients with TB were included in the final analysis. The weighted pooled prevalence of any anti-TB drug resistance was 14.25% (95% confidence interval (CI): 7.05–21.44%)), whereas the pooled prevalence of any INH and RIF resistance was found in 15.62% (95%CI: 6.77–24.47%) and 9.75% (95%CI: 4.69–14.82%) of patients with TB, respectively. The pooled prevalence for INH and RIF-monoresistance was 6.23% (95%CI: 4.44–8.02%) and 2.33% (95%CI: 1.00–3.66%), respectively. MDR-TB was detected in 2.64% (95%CI: 1.46–3.82%) of newly diagnosed cases and 11.54% (95%CI: 2.12–20.96%) of retreated patients with TB, while the overall pooled prevalence of MDR-TB was 10.78% (95%CI: 4.74–16.83%). Conclusions: In Ethiopia, anti-tuberculosis drug resistance is widespread. The estimated pooled prevalence of INH and RIF-monoresistance rates were significantly higher in this review than in previous reports. Moreover, MDR-TB in newly diagnosed cases remained strong. Thus, early detection of TB cases, drug-resistance testing, proper and timely treatment, and diligent follow-up of TB patients all contribute to the improvement of DR-TB management and prevention. Besides this, we urge that a robust, routine laboratory-based drug-resistance surveillance system be implemented in the country.