Factors Associated With Sputum Culture-Negative vs Culture-Positive Diagnosis of Pulmonary Tuberculosis

Determination of latent tuberculosis infection from plasma samples via label-free SERS sensors and machine learning

Effective diagnostic tools for screening of latent tuberculosis infection (LTBI) are lacking. We aim to investigate the performance of LTBI diagnostic approaches using label-free surface-enhanced Raman spectroscopy (SERS). We used 1000 plasma samples from Northeast Thailand. Fifty percent of the samples had tested positive in the interferon-gamma release assay (IGRA) and 50 % negative. The SERS investigations were performed on individually prepared protein specimens using the Raman-mapping technique over a 7 × 7 grid area under measurement conditions that took under 10 min to complete. The machine-learning analysis approaches were optimized for the best diagnostic performance. We found that the SERS sensors provide 81 % accuracy according to train-test split analysis and 75 % for LOOCV analysis from all samples, regardless of the batch-to-batch variation of the sample sets and SERS chip. The accuracy increased to 93 % when the logistic regression model was used to analyze the last three batches of samples, following optimization of the sample collection, SERS chips, and database. We demonstrated that SERS analysis with machine learning is a potential diagnostic tool for LTBI screening.

Clinical and Imaging Characteristics of Smear Negative Pulmonary Tuberculosis Patients: A Comparative Study

Background

Prevalence surveys in Ethiopia indicate smear negative pulmonary tuberculosis (SNPTB) taking the major share of the overall TB burden. It has also been a diagnostic dilemma worldwide leading to diagnostic delays and difficulty in monitoring treatment outcomes. This study determines and compares the clinical and imaging findings in SNPTB and smear positive PTB (SPPTB). Methodology. A case-control study was conducted on 313 PTB (173 SNPTB) patients. Data and sputum samples were collected from consented patients. Smear microscopy, GeneXpert, and culture analyses were performed on sputum samples. Data were analyzed using Stata version 17; a P value < 0.05 was considered statistically significant.

Results

Of the 173 SNPTB patients, 42% were culture positive with discordances between test results reported by health facilities and Armauer Hansen Research Institute laboratory using concentrated smear microscopy. A previous history of TB and fewer cavitary lesions were significantly associated with SNPTB.

Conclusions

Though overall clinical presentations of SNPTB patients resemble those seen in SPPTB patients, a prior history of TB was strongly associated with SNPTB. Subject to further investigations, the relatively higher discrepancies seen in TB diagnoses reflect the posed diagnostic challenges in SNPTB patients, as a higher proportion of these patients are also seen in Ethiopia.

Comparison of 3 diagnostic methods for pulmonary tuberculosis in suspected patients with negative sputum smear or no sputum

STUDY DESIGN

To explore the diagnostic value of 3 methods for sputum smear-negative and non-sputum patients with suspected pulmonary tuberculosis (TB).

METHODS

This prospective study enrolled sputum smear-negative and non-sputum patients with suspected TB admitted to Jiangxi Chest Hospital between January 2020 and December 2022. The 3 methods were bronchoalveolar lavage fluid (BALF)-acid-fast bacillus (AFB) smear, GeneXpert MTB/RIF, and gene chip for Mycobacterium strain identification. The diagnostic performance of the 3 tests was evaluated with BALF Mycobacterium culture + BALF-AFB smear + GeneXpert MTB/RIF + Gene chip as the gold standard.

RESULTS

A total of 456 samples were collected from 114 patients with suspected TB. Twenty-four patients were diagnosed with TB. The combination of GeneXpert MTB/RIF and gene chip for Mycobacterium strain identification yielded the highest area under the receiver operating characteristics curve (AUC) of 0.953 and had sensitivity of 90.57%, specificity of 100%, positive predictive value (PPV) of 100%, negative predictive value (NPV) of 92.42%, accuracy of 95.61%. GeneXpert MTB/RIF achieved AUC of 0.906, sensitivity of 81.13%, specificity of 100%, PPV of 100%, NPV of 85.92%, accuracy of 91.23%. BALF-AFB smear had AUC of 0.519, sensitivity of 3.77%, specificity of 100%, PPV of 100%, NPV of 54.46%, and accuracy of 55.26%. The combination of GeneXpert MTB/RIF and gene chip for Mycobacterium strain identification yielded the highest κ of 0.911, while BALF-AFB smear had the lowest κ value of 0.040.

CONCLUSION

For TB in sputum smear-negative and non-sputum patients using BALF Mycobacterium culture + BALF-AFB smear + GeneXpert MTB/RIF + Gene chip as the gold standard, BALF-AFB smear showed low diagnostic performance, while, though GeneXpert MTB/RIF and gene chip had good diagnostic performance, combining GeneXpert MTB/RIF and gene chip improved the diagnostic value to a great extent.

Spatial modeling of Mycobacterium tuberculosis transmission with dyadic genetic relatedness data

Understanding factors that contribute to the increased likelihood of pathogen transmission between two individuals is important for infection control. However, analyzing measures of pathogen relatedness to estimate these associations is complicated due to correlation arising from the presence of the same individual across multiple dyadic outcomes, potential spatial correlation caused by unmeasured transmission dynamics, and the distinctive distributional characteristics of some of the outcomes. We develop two novel hierarchical Bayesian spatial methods for analyzing dyadic pathogen genetic relatedness data, in the form of patristic distances and transmission probabilities, that simultaneously address each of these complications. Using individual-level spatially correlated random effect parameters, we account for multiple sources of correlation between the outcomes as well as other important features of their distribution. Through simulation, we show the limitations of existing approaches in terms of estimating key associations of interest, and the ability of the new methodology to correct for these issues across datasets with different levels of correlation. All methods are applied to Mycobacterium tuberculosis data from the Republic of Moldova, where we identify previously unknown factors associated with disease transmission and, through analysis of the random effect parameters, key individuals, and areas with increased transmission activity. Model comparisons show the importance of the new methodology in this setting. The methods are implemented in the R package GenePair.

Predictive capabilities of baseline radiological findings for early and late disease outcomes within sensitive and multi-drug resistant tuberculosis cases

Purpose

This study compares performance of Timika Score to standardized, detailed radiologist observations of Chest X rays (CXR) for predicting early infectiousness and subsequent treatment outcome in drug sensitive (DS) or multi-drug resistant (MDR) tuberculosis cases. It seeks improvement in prediction of these clinical events through these additional observations.

Method

This is a retrospective study analyzing cases from the NIH/NIAID supported TB Portals database, a large, trans-national, multi-site cohort of primarily drug-resistant tuberculosis patients. We analyzed patient records with sputum microscopy readings, radiologist annotated CXR, and treatment outcome including a matching step on important covariates of age, gender, HIV status, case definition, Body Mass Index (BMI), smoking, drug use, and Timika Score across resistance type for comparison.

Results

2142 patients with tuberculosis infection (374 with poor outcome and 1768 with good treatment outcome) were retrospectively reviewed. Bayesian ANOVA demonstrates radiologist observations did not show greater predictive ability for baseline infectiousness (0.77 and 0.74 probability in DS and MDR respectively); however, the observations provided superior prediction of treatment outcome (0.84 and 0.63 probability in DS and MDR respectively). Estimated lung abnormal area and cavity were identified as important predictors underlying the Timika Score's performance.

Conclusions

Timika Score simplifies the usage of baseline CXR for prediction of early infectiousness of the case and shows comparable performance to using detailed, standardized radiologist observations. The score's utility diminishes for treatment outcome prediction and is exceeded by the usage of the detailed observations although prediction performance on treatment outcome decreases especially in MDR TB cases.

Concomitant Treatment of Tuberculosis and Hepatitis C Virus in Coinfected Patients Using Serum Drug Concentration Monitoring

Background

Concern for drug-drug interactions leading to treatment failure and drug-resistant strains have discouraged clinicians from attempting concomitant treatment of hepatitis C virus (HCV) and tuberculosis (TB). Increased metabolism of direct-acting antivirals (DAAs) by rifamycins has hindered concurrent use. Development of an assay for ledipasvir and sofosbuvir (LDV/SOF) serum concentrations for therapeutic drug monitoring (TDM) can ensure adequate therapy. We present the first cases of concomitant therapy of active TB and HCV with rifamycin-containing regimens and DAAs using TDM.

Methods

Using TDM, we aim to determine whether concomitant therapy with rifamycin-containing regimens and DAAs is safe and effective for patients coinfected with TB and HCV. Five individuals with TB and HCV who experienced transaminitis before or during TB therapy were concomitantly treated with rifamycin-containing regimens and LDV/SOF. Therapeutic drug monitoring was performed for LDV, SOF, and rifabutin during therapy. Baseline laboratory tests and serial liver enzymes were performed. Hepatitis C virus viral load and mycobacterial sputum cultures were obtained upon completion of therapy to determine efficacy of therapy.

Results

All patients were found to have nondetectable HCV viral loads and negative mycobacterial sputum cultures upon completion of therapy. No clinically significant adverse effects were reported.

Conclusions

These cases illustrate concomitant use of LDV/SOF and rifabutin in patients with HCV/TB coinfection. Utilizing serum drug concentration monitoring to guide dosing, correction of transaminitis were achieved, which allowed the use rifamycin-containing TB therapy. These findings suggest that concomitant therapy of TB/HCV is possible, safe, and effective.

Do private providers initiate anti-tuberculosis therapy on the basis of chest radiographs? A standardised patient study in urban India

Background

The initiation of anti-tuberculosis treatment (ATT) based on results of WHO-approved microbiological diagnostics is an important marker of quality tuberculosis (TB) care. Evidence suggests that other diagnostic processes leading to treatment initiation may be preferred in high TB incidence settings. This study examines whether private providers start anti-TB therapy on the basis of chest radiography (CXR) and clinical examinations.

Methods

This study uses the standardized patient (SP) methodology to generate accurate and unbiased estimates of private sector, primary care provider practice when a patient presents a standardized TB case scenario with an abnormal CXR. Using multivariate log-binomial and linear regressions with standard errors clustered at the provider level, we analyzed 795 SP visits conducted over three data collection waves from 2014 to 2020 in two Indian cities. Data were inverse-probability-weighted based on the study sampling strategy, resulting in city-wave-representative results.

Findings

Amongst SPs who presented to a provider with an abnormal CXR, 25% (95% CI: 21-28%) visits resulted in ideal management, defined as the provider prescribing a microbiological test and not offering a concurrent prescription for a corticosteroid or antibiotic (including anti-TB medications). In contrast, 23% (95% CI: 19-26%) of 795 visits were prescribed anti-TB medications. Of 795 visits, 13% (95% CI: 10-16%) resulted in anti-TB treatment prescriptions/dispensation and an order for confirmatory microbiological testing.

Interpretation

One in five SPs presenting with abnormal CXR were prescribed ATT by private providers. This study contributes novel insights to empiric treatment prevalence based on CXR abnormality. Further work is needed to understand how providers make trade-offs between existing diagnostic practices, new technologies, profits, clinical outcomes, and the market dynamics with laboratories.

Funding

This study was funded by the Bill & Melinda Gates Foundation (grant OPP1091843), and the Knowledge for Change Program at The World Bank.

Epidemiology of Culture-Negative Pulmonary Tuberculosis-Alameda County, 2010-2019

CONTEXT

Patients with culture-negative pulmonary TB (PTB) can face delays in diagnosis that worsen outcomes and lead to ongoing transmission. An understanding of current trends and characteristics of culture-negative PTB can support earlier detection and access to care.

OBJECTIVE

Describe epidemiology of culture-negative PTB.

DESIGN, SETTING, PARTICIPANTS

We utilized Alameda County TB surveillance data from 2010 to 2019. Culture-negative PTB cases met clinical but not laboratory criteria for PTB per US National Tuberculosis Surveillance System definitions. We calculated trends in annual incidence and proportion of culture-negative PTB using Poisson and weighted linear regression, respectively. We further compared demographic and clinical characteristics among culture-negative versus culture-positive PTB cases.

RESULTS

During 2010-2019, there were 870 cases of PTB, of which 152 (17%) were culture-negative. The incidence of culture-negative PTB declined by 76%, from 1.9/100 000 to 0.46/100 000 ( P for trend <.01), while the incidence of culture-positive PTB reduced by 37% (6.5/100 000 to 4.1/100 000, P for trend =.1). Culture-negative PTB case-patients were more likely than culture-positive PTB case-patients to be younger (7.9% were children <15 years old vs 1.1%; P < .01), recent immigrants within 5 years of arrival (38.2% vs 25.5%; P < .01), and have a TB contact (11.2% vs 2.9%; P < .01). Culture-negative PTB case-patients were less likely than culture-positive PTB case-patients to be evaluated because of TB symptoms (57.2% vs 74.7%; P < .01) or have cavitation on chest imaging (13.1% vs 38.8%; P < .01). At the same time culture-negative PTB case-patients were less likely to die during TB treatment (2.0% vs 9.6%; P < .01).

CONCLUSIONS

The incidence of culture-negative PTB disproportionately declined compared with culture-positive TB and raises concern for gaps in detection. Expansion of screening programs for recent immigrants and TB contacts and greater recognition of risk factors may increase detection of culture-negative PTB.

A Mycobacterium tuberculosis fingerprint in human breath allows tuberculosis detection

An estimated one-third of tuberculosis (TB) cases go undiagnosed or unreported. Sputum samples, widely used for TB diagnosis, are inefficient at detecting infection in children and paucibacillary patients. Indeed, developing point-of-care biomarker-based diagnostics that are not sputum-based is a major priority for the WHO. Here, in a proof-of-concept study, we tested whether pulmonary TB can be detected by analyzing patient exhaled breath condensate (EBC) samples. We find that the presence of Mycobacterium tuberculosis (Mtb)-specific lipids, lipoarabinomannan lipoglycan, and proteins in EBCs can efficiently differentiate baseline TB patients from controls. We used EBCs to track the longitudinal effects of antibiotic treatment in pediatric TB patients. In addition, Mtb lipoarabinomannan and lipids were structurally distinct in EBCs compared to ex vivo cultured bacteria, revealing specific metabolic and biochemical states of Mtb in the human lung. This provides essential information for the rational development or improvement of diagnostic antibodies, vaccines and therapeutic drugs. Our data collectively indicate that EBC analysis can potentially facilitate clinical diagnosis of TB across patient populations and monitor treatment efficacy. This affordable, rapid and non-invasive approach seems superior to sputum assays and has the potential to be implemented at point-of-care.

Bacteriomes in lesions of pulmonary tuberculosis and its association with status of Mycobacterium tuberculosis excretion

BACKGROUND

Bacteria in lung play an important role in sustaining lung health. Understanding the characteristics of bacteriomes in lesions of pulmonary tuberculosis (TB) patients, who excrete Mycobacterium tuberculosis (MTB), is important for TB prevention and effective treatment.  METHODS: In this study, bacteriomes in lesions from TB patients excreting bacteria (TB-E) and those from TB patients not excreting bacteria (TB-NE) with matched normal lung tissues (NT) were compared by 16S rRNA sequencing. Bacterial MetaCyc functions in TB lesions were also predicted by PICRUSt2 tool.

RESULTS

Alpha diversity of bacteria, including Chao 1 and Shannon indexes, for TB-E was significantly higher than those in TB-NE and NT; while for TB-NE group, Chao 1 index was higher than that in NT group. Predominant phyla in TB lesions and NT were Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes, but analysis of similarity (ANOSIM, p < 0.001) revealed significantly different bacterial compositions among TB-E, TB-NE and NT samples. As for bacteriomes in TB lesions, a strong association (ANOSIM, p < 0.001) was observed with the status of MTB excretion. Indicator genera identified in TB-E and TB-NE demonstrated distinctive micro-ecological environments of TB lesions from patients with different clinical manifestations. Co-occurrence analysis revealed a densely-linked bacterial community in TB-NE compared to that in TB-E. MetaCyc functions responsible for menaquinone synthesis and chorismate metabolism that could potentially impact the persistent-state and nutrient metabolism of MTB were enriched in TB-E samples. While in TB-NE samples, enrichment of bacterial MetaCyc function responsible for heme b synthesis might contribute to TB pathology through ferroptosis.

CONCLUSION

Bacteriomes and their MetaCyc functions in TB lesions are elucidated, and they are associated with status of MTB excretion among pulmonary TB patients. These results serve as a basis for designing novel strategies for preventing and treating pulmonary TB disease.

Diagnostic biomarkers for active tuberculosis: progress and challenges

Tuberculosis (TB) is a leading cause of morbidity and mortality from a single infectious agent, despite being preventable and curable. Early and accurate diagnosis of active TB is critical to both enhance patient care, improve patient outcomes, and break Mycobacterium tuberculosis (Mtb) transmission cycles. In 2020 an estimated 9.9 million people fell ill from Mtb, but only a little over half (5.8 million) received an active TB diagnosis and treatment. The World Health Organization has proposed target product profiles for biomarker- or biosignature-based diagnostics using point-of-care tests from easily accessible specimens such as urine or blood. Here we review and summarize progress made in the development of pathogen- and host-based biomarkers for active TB diagnosis. We describe several unique patient populations that have posed challenges to development of a universal diagnostic TB biomarker, such as people living with HIV, extrapulmonary TB, and children. We also review additional limitations to widespread validation and utilization of published biomarkers. We conclude with proposed solutions to enhance TB diagnostic biomarker validation and uptake.

Pelvic and central nervous system tuberculosis complicated by a paradoxical response manifesting as a spinal tuberculoma: a case report

Background

The post-partum period is a risk factor for tuberculosis (TB), possibly including the period after miscarriage as illustrated here. This case demonstrates how non-specific symptoms can hide widely disseminated TB.

Case presentation

A healthy 26-year-old female with a history of recent miscarriage presented to the emergency department with non-specific symptoms of headache, abdominal pain, and sub-acute fevers. She had immigrated to the United States from the Marshall Islands 9 years prior. Two months prior to presentation she had a miscarriage at 18 weeks of pregnancy. On admission, transvaginal ultrasound revealed retained products of conception and abdominal computed tomography revealed findings consistent with tubo-ovarian abscesses and peritonitis. The obstetrics and gynecology service performed dilation and curettage (D&C) to remove retained products of conception. Acid-fast bacilli cultures from cerebrospinal fluid as well as specimens from D&C and intra-abdominal abscesses subsequently all grew TB. She was diagnosed with TB meningitis, peritonitis, endometritis, and tubo-ovarian abscesses. Her treatment course was complicated by a paradoxical response resulting in a spinal tuberculoma causing lower extremity weakness. The tuberculoma was treated with surgical decompression as well as continuation of treatment with anti-tubercular chemotherapy and steroids.

Conclusion

Disseminated and extrapulmonary TB can present with non-specific symptoms. Recognition of risk factors for TB is critical for prompt diagnostic evaluation and treatment of this deadly disease. A paradoxical reaction needs to be taken into consideration when any new neurological symptoms occur during TB treatment.

Mind the gap - Managing tuberculosis across the disease spectrum

We currently have a binomial approach to managing tuberculosis. Those with active disease, ideally confirmed microbiologically, are treated with a standard 6-month, multi-drug regimen and those with latent infection and no evidence of disease with shorter, one or two drug regimens. Clinicians frequently encounter patients that fall between these two management pathways with some but not all features of disease and this will occur more often with the increasing emphasis on chest X-ray-based systematic screening. The view of tuberculosis as a spectrum of disease states is being increasingly recognised and is leading to new diagnostic approaches for early disease. However, the 6-month regimen for treating disease was driven by the duration required to treat the most extensive forms of pulmonary TB and shorter durations appear sufficient for less extensive disease. It is time undertake clinical trials to better define the optimal treatment for tuberculosis across the disease spectrum.

Characterization of Drug-Resistant Lipid-Dependent Differentially Detectable Mycobacterium tuberculosis

An estimated 15–20% of patients who are treated for pulmonary tuberculosis (TB) are culture-negative at the time of diagnosis. Recent work has focused on the existence of differentially detectable Mycobacterium tuberculosis (Mtb) bacilli that do not grow under routine solid culture conditions without the addition of supplementary stimuli. We identified a cohort of TB patients in Lima, Peru, in whom acid-fast bacilli could be detected by sputum smear microscopy, but from whom Mtb could not be grown in standard solid culture media. When we attempted to re-grow Mtb from the frozen sputum samples of these patients, we found that 10 out of 15 could be grown in a glycerol-poor/lipid-rich medium. These fell into the following two groups: a subset that could be regrown in glycerol after “lipid-resuscitation”, and a group that displayed a heritable glycerol-sensitive phenotype that were unable to grow in the presence of this carbon source. Notably, all of the glycerol-sensitive strains were found to be multidrug resistant. Although whole-genome sequencing of the lipid-resuscitated strains identified 20 unique mutations compared to closely related strains, no single genetic lesion could be associated with this phenotype. In summary, we found that lipid-based media effectively fostered the growth of Mtb from a series of sputum smear-positive samples that were not culturable in glycerol-based Lowenstein–Jensen or 7H9 media, which is consistent with Mtb’s known preference for non-glycolytic sources during infection. Analysis of the recovered strains demonstrated that both genetic and non-genetic mechanisms contribute to the observed differential capturability, and suggested that this phenotype may be associated with drug resistance.

Pulmonary Tuberculosis Disease Among Immigrant Detainees: Rapid Disease Detection, High Prevalence of Asymptomatic Disease, and Implications for Tuberculosis Prevention

BACKGROUND

Rapid screening for tuberculosis (TB) disease at intake into immigrant detention facilities allows for early detection and treatment. Detention facilities with United States Immigration and Customs Enforcement (ICE) Health Service Corps (IHSC) medical staffing utilize chest radiography and symptom screening as the primary screening for pulmonary TB (PTB) disease. This analysis describes the demographic, clinical, and microbiological characteristics of individuals identified with TB disease at these facilities.

METHODS

We conducted a retrospective analysis to describe the population of immigrant detainees identified via chest radiography with PTB disease between 1 January 2014 and 31 December 2016 at facilities with IHSC medical staffing. We collected demographic variables, clinical presentation, diagnostic testing results, and microbiological findings. We generated descriptive statistics and examined univariate and multivariate associations between the variables collected and symptomatic status.

RESULTS

We identified 327 patients with confirmed PTB disease (incidence rate, 92.8 per 100 000); the majority of patients were asymptomatic (79.2%) at diagnosis. Adjusting for all other variables in the model, the presence of cavitary lesions, acid-fast bacillus smear positivity, and multilobar presentation were significantly associated with symptomatic status. Among all patients identified with TB disease who had a tuberculin skin test (TST) result recorded, 27.2% were both asymptomatic and TST negative, including those with smear-positive disease.

CONCLUSIONS

Asymptomatic PTB disease is a significant clinical entity among immigrant detainees and placement in a congregate setting calls for aggressive screening to prevent transmission. Early identification, isolation, and treatment of TB disease benefit not only the health of the patient, but also the surrounding community.

Metagenomic analysis of the lung microbiome in pulmonary tuberculosis - a pilot study

The lung microbiome plays an important role in the pathophysiological processes associated with pulmonary tuberculosis (PTB). However, only a few studies using 16S rDNA amplicon sequencing have been reported, and the interactions between Mycobacterium tuberculosis (MTB) and the lung microbiome remain poorly understood. Patients with respiratory symptoms and imaging abnormalities compatible with tuberculosis (TB) were enrolled. We analyzed the lung microbiome in bronchoalveolar lavage (BAL) samples from 30 MTB-positive (MTB+) subjects and 30 MTB negative (MTB-) subjects by shotgun metagenomic sequencing. Alpha diversity tended to be lower in the MTB+ group than in the MTB- group. There was a significant difference in beta diversity between the MTB+ and MTB- subjects. MTB+ lung samples were dominated by MTB, while MTB- samples were enriched with Streptococcus, Prevotella, Nesseria, Selenomonas and Bifidobacterium, which more closely resemble the microbial composition of a healthy lung. Network analysis suggested that MTB could greatly impact the microbial community structure. MTB+ and MTB- communities showed distinct functional signatures. Fungal communities were also found to be associated with the presence or absence of MTB. Furthermore, it was confirmed that 16S rDNA amplicon sequencing underrepresents Mycobacterium. This pilot study is the first to explore the interplay between MTB and the host microbiome by using metagenomic sequencing. MTB dominates the lung microbiome of MTB+ subjects, while MTB- subjects have a Streptococcus-enriched microbiome. The 16S approach underrepresents Mycobacterium and is not the best way to study the TB-associated microbiome.

Trade-offs between cost and accuracy in active case finding for tuberculosis: A dynamic modelling analysis

BACKGROUND

Active case finding (ACF) may be valuable in tuberculosis (TB) control, but questions remain about its optimum implementation in different settings. For example, smear microscopy misses up to half of TB cases, yet is cheap and detects the most infectious TB cases. What, then, is the incremental value of using more sensitive and specific, yet more costly, tests such as Xpert MTB/RIF in ACF in a high-burden setting?

METHODS AND FINDINGS

We constructed a dynamic transmission model of TB, calibrated to be consistent with an urban slum population in India. We applied this model to compare the potential cost and impact of 2 hypothetical approaches following initial symptom screening: (i) 'moderate accuracy' testing employing a microscopy-like test (i.e., lower cost but also lower accuracy) for bacteriological confirmation and (ii) 'high accuracy' testing employing an Xpert-like test (higher cost but also higher accuracy, while also detecting rifampicin resistance). Results suggest that ACF using a moderate-accuracy test could in fact cost more overall than using a high-accuracy test. Under an illustrative budget of US$20 million in a slum population of 2 million, high-accuracy testing would avert 1.14 (95% credible interval 0.75-1.99, with p = 0.28) cases relative to each case averted by moderate-accuracy testing. Test specificity is a key driver: High-accuracy testing would be significantly more impactful at the 5% significance level, as long as the high-accuracy test has specificity at least 3 percentage points greater than the moderate-accuracy test. Additional factors promoting the impact of high-accuracy testing are that (i) its ability to detect rifampicin resistance can lead to long-term cost savings in second-line treatment and (ii) its higher sensitivity contributes to the overall cases averted by ACF. Amongst the limitations of this study, our cost model has a narrow focus on the commodity costs of testing and treatment; our estimates should not be taken as indicative of the overall cost of ACF. There remains uncertainty about the true specificity of tests such as smear and Xpert-like tests in ACF, relating to the accuracy of the reference standard under such conditions.

CONCLUSIONS

Our results suggest that cheaper diagnostics do not necessarily translate to less costly ACF, as any savings from the test cost can be strongly outweighed by factors including false-positive TB treatment, reduced sensitivity, and foregone savings in second-line treatment. In resource-limited settings, it is therefore important to take all of these factors into account when designing cost-effective strategies for ACF.

Evaluation of the performance of clinical predictors in estimating the probability of pulmonary tuberculosis among smear-negative cases in Northern Ethiopia: a cross-sectional study

OBJECTIVES

To evaluate the performance of the predictors in estimating the probability of pulmonary tuberculosis (PTB) when all versus only significant variables are combined into a decision model (1) among all clinical suspects and (2) among smear-negative cases based on the results of culture tests.

DESIGN

A cross-sectional study.

SETTING

Two public referral hospitals in Tigray, Ethiopia.

PARTICIPANTS

A total of 426 consecutive adult patients admitted to the hospitals with clinical suspicion of PTB were screened by sputum smear microscopy and chest radiograph (chest X-ray (CXR)) in accordance with the Ethiopian guidelines of the National Tuberculosis and Leprosy Program. Discontinuation of antituberculosis therapy in the past 3 months, unproductive cough, HIV positivity and unwillingness to give written informed consent were the basis of exclusion from the study.

PRIMARY AND SECONDARY OUTCOME MEASURES

A total of 354 patients were included in the final analysis, while 72 patients were excluded because culture tests were not done.

RESULTS

The strongest predictive variables of culture-positive PTB among patients with clinical suspicion were a positive smear test (OR 172; 95% CI 23.23 to 1273.54) and having CXR lesions compatible with PTB (OR 10.401; 95% CI 5.862 to 18.454). The regression model had a good predictive performance for identifying culture-positive PTB among patients with clinical suspicion (area under the curve (AUC) 0.84), but it was rather poor in patients with a negative smear result (AUC 0.64). Combining all the predictors in the model compared with only the independent significant variables did not really improve its performance to identify culture-positive (AUC 0.84-0.87) and culture-negative (AUC 0.64-0.69) PTB.

CONCLUSIONS

Our finding suggests that predictive models based on clinical variables will not be useful to discriminate patients with culture-negative PTB from patients with culture-positive PTB among patients with smear-negative cases.

A descriptive study of smear negative pulmonary tuberculosis in a high HIV burden patient's population in North Central Nigeria

Tuberculosis (TB) is a serious disease of public health concern, mainly in low- and middle-income countries. Most of these countries have challenges in diagnosis and treatment of TB in people with smear-negative pulmonary tuberculosis (SNPTB), which remains a significant public health challenge because of the global burden of the disease. We evaluated the epidemiology and clinical presentation of SNPTB in a cohort of patients with high HIV burden. The study was a cross-sectional study among patients with SNPTB in four major hospitals that care for TB/HIV patients in north-central Nigeria. All patients 18 years and above who were newly diagnosed as SNPTB, or patients with SNPTB who had not taken TB drugs for up to 2 weeks irrespective of their HIV status were recruited. Demographic data (sex, age), smoking status, and medical history (clinical form of TB, symptoms at admission, diagnostic methods, presence of comorbidities, prior TB treatment) were obtained using a semi-structured questionnaire. Detailed clinical examination was also done on all the study subjects. Baseline results of packed cell volume, HIV test and sputum acid fast bacilli done during TB screening were retrieved from the patients' case notes and recorded. Also, the base line Chest X-ray films taken during TB screening were reviewed and reported by two radiologists blinded to each other's reports. The Xpert MTB/RIF tests and sputum culture (using LJ medium) were done in a TB reference laboratory. A total of 150 patients with SNPTB were studied. Majority of the patients were female 93 (62%). The median age of the patients was 36.5 years with greater percentage of the patients within the ages of 25-44 years 92 (61.3%). Twenty-two (14.7%) of the patients had previous TB treatment. History of cigarette smoking was obtained in only 7(4.7%) of the patients while 82 (64.1%) were HIV positive. All the patients had a history of cough for over a period of at least three weeks, while, 27 (18%) reported having hemoptysis. About 87 (58%) had fever and 110 (73.7%) had anemia, while weight loss and night sweat were reported in 98(65.3%) and 82 (54.7%) of the patients respectively. Chest x rays were reported as typical of TB in only 24 (16%) of the patients. Of the 150 sputa sample analyzed, 21/150 (14.0%) and 22/150 (14.7%) where Gene Xpert and sputum culture positive respectively. The sensitivity and specificity of Gene Xpert assay were 81.8% (18/22; 95% CI 61.5 to 92.7%) and 97.4% (112/115; 95% CI 92.6 to 99.1%), respectively. The study found cough, fever and anemia to be the commonest presentation in patient with SNPTB in a high HIV burden patient's population. There is also relatively high culture positivity among the patients. This underscores the need to expand the facilities for culture and confirmation in TB centers across the country.

Comparison of different bacteriological testing strategies and factors for bacteriological confirmation among pulmonary TB patients: a retrospective study in Tianjin, China, 2017-2018

Background

Bacteriological confirmation (BC) proportion among notified pulmonary TB patients in China is among the lowest in the world. This study was to understand the yield of BC using different testing strategies and patient-level factors associated with BC among pulmonary TB patients in Tianjin, China during 2017–2018.

Methods

A retrospective study was conducted, enrolling pulmonary TB patients reported to National TB Information Management System (TBIMS) in Tianjin during 2017–2018. BC was defined as a positive result by any of the followings: smear microscopy, culture, or nucleic acid amplification test. Individual characteristics were compared between patients with positive and negative bacteriological results using contingency tables and χ² test. Multivariable logistic regression was applied to analyze factors associated with BC, calculating adjusted odds ratios (aOR) and 95% confidence intervals (CI) (α = 0.05).

Results

Of 6364 reported patients, 4181 (65.7%) were bacteriologically confirmed. Positivity proportion was 43.1% (2746/6364) for smear microscopy, 57.7% (3380/5853) for culture, 61.7% (1608/2605) for Xpert® MTB/RIF assay (Xpert) and 73.4% (1824/2484) for combination of the three. The unemployed (aOR = 1.5, 95% CI: 1.0–2.2) and farmers (aOR = 1.7, 95% CI: 1.1–2.8) compared with students; diagnosis by inpatient hospitals compared with TB clinics (aOR = 3.4, 95% CI: 2.6–4.4); having symptoms for ≥2 weeks (aOR = 1.4, 95% CI: 1.1–1.8); cough (aOR = 2.2, 95% CI: 1.8–2.8); blood sputum (aOR = 1.5, 95% CI: 1.0–2.2); cavitation on chest X-ray (aOR = 3.3, 95% CI: 2.5–4.3); bilateral lung lobes affected (aOR = 1.7, 95% CI: 1.4–2.2) were factors associated with BC.

Conclusions

Combination test was an effective way to improve BC among pulmonary TB patients. Being unemployed, farmers, having prolonged symptoms, and more severe in TB condition were factors associated with BC. We recommend combination of tests to improve BC for pulmonary TB patients, especially who are in early stage of the disease or with conditions tend to be bacteriologically negative.

Mobilising community networks for early identification of tuberculosis and treatment initiation in Cambodia: an evaluation of a seed-and-recruit model

Background and objectives

The effects of active case finding (ACF) models that mobilise community networks for early identification and treatment of tuberculosis (TB) remain unknown. We investigated and compared the effect of community-based ACF using a seed-and-recruit model with one-off roving ACF and passive case finding (PCF) on the time to treatment initiation and identification of bacteriologically confirmed TB.

Methods

In this retrospective cohort study conducted in 12 operational districts in Cambodia, we assessed relationships between ACF models and: 1) the time to treatment initiation using Cox proportional hazards regression; and 2) the identification of bacteriologically confirmed TB using modified Poisson regression with robust sandwich variance.

Results

We included 728 adults with TB, of whom 36% were identified via the community-based ACF using a seed-and-recruit model. We found community-based ACF using a seed-and-recruit model was associated with shorter delay to treatment initiation compared to one-off roving ACF (hazard ratio 0.81, 95% CI 0.68-0.96). Compared to one-off roving ACF and PCF, community-based ACF using a seed-and-recruit model was 45% (prevalence ratio (PR) 1.45, 95% CI 1.19-1.78) and 39% (PR 1.39, 95% CI 0.99-1.94) more likely to find and detect bacteriologically confirmed TB, respectively.

Conclusion

Mobilising community networks to find TB cases was associated with early initiation of TB treatment in Cambodia. This approach was more likely to find bacteriologically confirmed TB cases, contributing to the reduction of risk of transmission within the community.

Quantitative analysis of serum-based IgG agalactosylation for tuberculosis auxiliary diagnosis

Tuberculosis (TB) is the leading infectious cause of mortality worldwide, especially in developing countries. However, effective means for TB diagnosis, especially for bacillus-negative (Bn) TB laboratory diagnosis, are urgently needed. In the present study, serum IgG from each tuberculosis patients and healthy controls was purified using affinity chromatography. The samples were then analyzed using mass spectrometry (MS) and ultraperformance liquid chromatography (UPLC) methods. We quantitatively assessed the changes of serum IgG galactosylation in 567 human serum samples including 377 pulmonary TB patients and 190 healthy donors (HDs). We found significantly more agalactosylated (G0) vs monogalactosylated (G1) and digalactosylated (G2) N-glycans of IgG in TB patients, including smear-negative TB patients, than in HDs. The detection rate of TB diagnostic performance by MS for IgG-Gal ratio G0/(G1 + G2 × 2) is 90.48% for bacillus-positive (Bp) and 73.16% for Bn TB patients. Further, combination of MS method with other routine laboratory TB diagnostic methods significantly increased the detection rate to 91.01%-98.39%. Similar results were observed in Mycobacterium tuberculosis (M. tb) infection mouse models. The decrease in galactosylation of IgG in TB patients was also qualitatively confirmed using specific lectin blot assay. Using the above techniques, we can discriminate the content of IgG G0 with terminal N-acetylglucosamine and IgG-Gal ratio G0/(G1 + G2 × 2) between TB patients and HDs. Our data suggest that quantitative analysis of serum-based IgG-Gal ratio G0/(G1 + G2 × 2) could be used for TB auxiliary diagnosis with high effectiveness and feasibility and its combination with other routine laboratory TB diagnostic methods could remarkably improve the detection rate.

A valuable computed tomography-based new diagnostic tool for severe chest lesions in active pulmonary tuberculosis: combined application of influencing factors

The objective of the present investigation was to explore the influencing factors and value of computed tomography (CT) for diagnosing severe chest lesions in active pulmonary tuberculosis (APTB). This retrospective investigation included 463 patients diagnosed with APTB. Relevant clinical features were collected. Patients were assigned to mild/moderate group or advanced group depending on the lesion severity on chest CT, severe chest CT lesion refers to the moderately dense or less diffuse lesion that exceeds the total volume of one lung, or the dense fusion lesion greater than one third of the volume of one lung, or the lesion with cavity diameter ≥4 cm. Independent risk factors for severe lesions were determined by univariate and multivariate logistic regression analyses, and the diagnostic efficiency of the risk factors was assessed by receiver operating characteristic curve (ROC). Chest CT demonstrated that there were 285 (61.56%) cases with severe lesions; multivariate Logistic regression analysis showed dust exposure [odds ratio (OR) = 4.108, 95% confidence interval (CI) 2.416–6.986], patient classification (OR = 1.792, 95% CI 1.067–3.012), age (OR = 1.018, 95% CI 1.005–1.030), and albumin-globulin ratio (OR = 0.179, 95% CI 0.084–0.383) to be independently correlated with severe lesions on chest CT. ROC curve analysis showed the cutoff values of age, albumin-globulin ratio and combined score to be 39 years, 0.918 and −0.085, respectively. The predictive value of combined score area under the curve 0.753 (95% CI 0.708–0.798) was higher than that of any single factor. The combined score of these four factors further improved the predictive efficacy.