Diagnostic Tests For Tuberculosis Research Articles

Constructing care cascades for active tuberculosis: A strategy for program monitoring and identifying gaps in quality of care.

The cascade of care is a model for evaluating patient retention across sequential stages of care required to achieve a successful treatment outcome. This approach was first used to evaluate HIV care and has since been applied to other diseases. The tuberculosis (TB) community has only recently started using care cascade analyses to quantify gaps in quality of care. In this article, we describe methods for estimating gaps (patient losses) and steps (patients retained) in the care cascade for active TB disease. We highlight approaches for overcoming challenges in constructing the TB care cascade, which include difficulties in estimating the population-level burden of disease and the diagnostic gap due to the limited sensitivity of TB diagnostic tests. We also describe potential uses of this model for evaluating the impact of interventions to improve case finding, diagnosis, linkage to care, retention in care, and post-treatment monitoring of TB patients.

Serum Exosomal miRNAs Are Associated with Active Pulmonary Tuberculosis.

Introduction Tuberculosis (TB) remains a major threat to human health. Due to the limited accuracy of the current TB diagnostic tests, it is critical to determine novel biomarkers for this disease. Circulating exosomes have been used as diagnostic biomarkers in various diseases. Objective of the Study In this pilot study, we examined the expression of miRNAs as biomarker candidates for the diagnosis of TB infection. Methods Serum-derived exosomes were isolated from TB patients and matched control subjects. The expression of miR-484, miR-425, and miR-96 was examined by RT-PCR methods. Results The expression of miR-484, miR-425, and miR-96 were significantly increased in serum of TB patients which correlated with the TB infection level. A receiver operating characteristic (ROC) curve analysis showed the diagnostic potency of each individual serum exosomal miRNA with an area under the curve (AUC) = 0.72 for miR-484 (p < 0.05), 0.66 for miR-425 (p < 0.05), and 0.62 for miR-96 (p < 0.05). Conclusion These results demonstrate that exosomal miRNAs have diagnostic potential in active tuberculosis. The diagnostic power may be improved when combined with conventional diagnostic markers.

Modelling the impact of chest X-ray and alternative triage approaches prior to seeking a tuberculosis diagnosis

BackgroundTuberculosis is a major challenge to health in the developing world. Triage prior to diagnostic testing could potentially reduce the volume of tests and costs associated with using the more accurate, but costly, Xpert MTB/RIF assay. An effective methodology to predict the impact of introducing triage prior to tuberculosis diagnostic testing could be useful in helping to guide policy.MethodsThe development and use of operational modelling to project the impact on case detection and health system costs of alternative triage approaches for tuberculosis, with or without X-ray, based on data from Porto Alegre City, Brazil.ResultsMost of the triage approaches modelled without X-ray were predicted to provide no significant benefit. One approach based on an artificial neural network applied to patient and symptom characteristics was projected to increase case detection (82% vs. 75%) compared to microscopy, and reduce costs compared to Xpert without triage. In addition, use of X-ray before diagnostic testing for HIV-negative patients could maintain diagnostic yield of using Xpert without triage, and reduce costs.ConclusionA model for the impact assessment of alternative triage approaches has been tested. The results from using the approach demonstrate its usefulness in informing policy in a typical high burden setting for tuberculosis.

Understanding tuberculosis: Examining its historical impact, modes of transmission, risk factors, and strategies for global prevention and effective treatment

Background: Tuberculosis (TB) is a highly infectious disease with a long history of impacting global health. Despite the availability of effective treatments, TB remains a significant cause of morbidity and mortality, particularly in low- and middle-income countries and among HIV-positive individuals. TB transmission occurs primarily through inhaling aerosolized droplets from an infected person, leading to potential disease progression. Risk factors for TB include close contact with infected individuals, residency in TB-endemic regions, and immunocompromising conditions like HIV and diabetes. Aim: This article aims to provide an overview of TB’s historical impact, modes of transmission, risk factors, diagnostic methods, and global strategies for prevention and treatment. Methods: The review synthesizes data from recent studies on TB transmission, clinical symptoms, imaging techniques, and diagnostic tests, including acid-fast bacilli (AFB) smear, nucleic acid amplification tests (NAATs), and immune-based tests. Various diagnostic and treatment protocols are discussed for both drug-susceptible and drug-resistant TB strains. Results: TB diagnosis relies on a combination of imaging, microbiologic testing, and immune-based tests. While AFB smears and NAATs remain primary diagnostic methods, novel imaging techniques like CT and PET scans are expanding diagnostic accuracy.

Newer Diagnostic Tests and their Application in Pediatric TB.

The diagnosis of childhood tuberculosis is a challenge due to the pauci-bacillary nature of infection and the difficulty in obtaining appropriate sample. In the past 2-3 decades, many new tests were introduced for the diagnosis of tuberculosis (TB) and some of them have been evaluated for their application in pediatric tuberculosis as well. There is an attempt to improve smear microscopy by introducing light-emitting diode (LED) fluorescence microscopy and there are also some automated digital microscopy platforms under evaluation. Introduction of automated liquid culture platform along with rapid molecular based identification methods have considerably reduced the time delay in mycobacterial culture. Recent addition of many nucleic acid amplification platforms like Amplicor PCR, Genprobe, Xpert MTB/Rif, line probe assays, loop mediated isothermal amplification etc are also been found to be useful. Latest techniques like microarray and gene sequencing are also being used in clinical laboratories with variable results. Indirect methods of TB diagnosis like T cell based assays including tuberculin skin test and interferon-gamma release assays have their role primarily in the diagnosis of latent TB. Biomarkers are the latest addition in the battery of TB diagnostic tests facilitating diagnosis using easily accessible samples like urine, blood and breath of patients. Many biomarkers are still under evaluation and some of them are found to have a potential role as promising diagnostic tests of future.

Common alternative diagnoses among a pediatric hospital-based cohort evaluated for tuberculosis in Karachi, Pakistan: The need for facilitated referral in tuberculosis clinics.

Children evaluated for tuberculosis (TB) are often diagnosed with miscellaneous conditions that mimic TB. Knowledge of differentials informs policy on service provision through liaison with referral centers offering definitive diagnosis and treatment for common alternative disorders. We reviewed medical records of children who were offered diagnostic testing for TB (culture or Xpert MTB/RIF) at a tertiary care hospital in Karachi, Pakistan to identify common alternative diagnoses among children who are evaluated for TB. From January 2014 to December 2015, of 126 culture or Xpert MTB/RIF negative children presenting with chronic symptoms, 31 were diagnosed and treated for TB based on clinical criteria (5 of 48 children with pulmonary and 26 of 78 with extrapulmonary presentations; 10.4% and 33.3%, respectively). Among remaining 95 patients, common alternative diagnoses to pulmonary TB (n = 43) were bacterial pneumonia or empyema (60.5%, n = 25) and underlying bronchiectasis (20.9%, n = 9). Among 52 extrapulmonary presentations, the most common alternative diagnoses were lymphoproliferative disorders (n = 11, 21.1%), bacterial infections (n = 11, 21.1%), and autoimmune disorders (n = 9, 17.3%). Of note, five children were diagnosed with underlying primary immunodeficiencies (9.6%). Children with alternative disorders were treated for TB in 25 of 95 cases (26.3%). Although 77.8% (n = 98) children were followed up at the facility, 15.9% (n = 20) were lost to follow-up. Pediatric TB mimics many disorders that primary level centers are not equipped to diagnose or manage, leading to suboptimal outcomes. Knowledge of common alternative diagnoses is essential to inform facilitated referral for common mimicking disorders in children.

Effect of Coinfection by fasciola hepatica and mycobacterium bovis on Bovine Tuberculosis Immunodiagnosis in an Enzootic Area Hidalgo State, Mexico.

Parasitic infection by the Fasciola hepatica (F. hepatica) promotes susceptibility towards other infections, such as Mycobacterium bovis. As consequence, could affect diagnostic tests for this disease. Hence, the objective of this study was to assess the impact of F. hepatica coinfection on the most commonly used immunodiagnostic bovine tuberculosis (bTB) tests in field conditions in an enzootic area for both diseases. Thus, from a dairy herd located in Hidalgo State, México, displaying a 59.2% and 28% prevalence of fascioliasis and bTB, respectively. Sixty-one cows were analyzed based on their response towards bTB immunodiagnostic tests, such as Single Intradermal Comparative Tuberculin Test (SICTT), gamma-interferon test (BOVIGAM) and enzyme-linked immunosorbent assay (ELISA), along with the assessment of the F. hepatica parasite load and serodiagnosis by ELISA. Three study groups were formed according to test results. Group 1: coinfected (n=22). Group 2: non-parasitized cows, and positive for bTB tests (n=13) and Group 3: parasitized cows without tuberculosis (n=26). In addition, a group of cows kept in fascioliasis - and tuberculosis-free zones were included (Group 4, n=10). A non-parametric Kruskal-Wallis test and a Dunn test were applied to analyze the results. In Group 1, significant differences were observed regarding IFN-γ production, but not for antibody levels to M. bovis or reactivity towards bovine PPD in relation Group 2. While, Groups 1 and 3 did not display difference in antibody levels against F. hepatica. Differences were observed regarding tuberculosis and Fasciola diagnostic tests when both coinfected and infected groups were compared to controls. It is concluded that F. hepatica coinfection in tuberculous animals studied, depressed the production of IFN-γ towards bovine PPD under in vitro conditions, but its reactivity to the SICTT not show to be altered.

Tuberculosis (TB) intervention model targeting mobile population of truckers in Delhi, India

Collaborative TB and HIV prevention and management activities are essential for reducing the burden of TB disease and achieving favorable outcomes by ensuring early initiation of antiretroviral therapy in the comorbid patients. The Mobile population of truckers and helpers is at higher risk of HIV and also TB infection. ObjectiveThe present study assessed the feasibility and opportunities for integrating TB screening and anti-tubercular drug dispensation services to truckers as an additional service utilizing the existing infrastructure and human resources of a targeted intervention (TI) based STI (Khushi) clinic and an integrated counseling and testing center (ICTC) operating at a transport hub and transshipment site in Delhi, India. MethodsThis exploratory operational research study was conducted at the Sanjay Gandhi Transport Nagar (SGTN), off the GT-Karnal highway, in North-west district of Delhi, the Indian capital city during May–Nov’ 2016.The proposed methodology for integration of comprehensive TB services within the existing STI/HIV services for the trucker population included a prevention and awareness component using interpersonal sessions, transporter meeting, one-on-one group session and IEC/BCC sessions utilizing a surround and engage technique. TB diagnostic testing and treatment services were provided through the collaboration with the TI/Khushi clinic and ICTC center staff aided by the field assistants. ResultsOverall, a total of 833 activity sessions were conducted during the study period among the truckers at the SGTN. During these sessions, 14644 truckers and 1444 other individuals were covered. A total of 297 truckers and 30 other people were referred for testing out of which 283 truckers and 33 others were tested for TB. Of these, ten truckers and four other individuals were found positive for TB. DiscussionThe present study provides the first patient (truckers) level evidence from India that routine, provider-initiated voluntary TB testing of truckers coming to avail services at STI and ICTC clinics for prevention and screening of HIV-AIDS is possible. The current practice of referral of HIV patients from the ICTC center to the chest clinic is inefficient since the opportunity costs and financial implications involved may deter patients from testing while the HIV negative but presumptive TB patients are likely to be missed. However, for this collaborative partnership to be successful, further investment regarding human and financial resources is necessary. Existing staff needs sensitization, training and proper incentives for conducting TB related IEC/BCC activities along with that for HIV-AIDS. Furthermore, the deployment of additional personnel is preferable for sputum collection and TB testing with the availability of early reporting at site.

Association of Radiological Findings with the Xpert MTB/RIF Test in Patients with Suspected Pulmonary Tuberculosis.

Tuberculosis (TB) treatment is often carried out empirically, based on clinical and radiological findings. Chest X-ray (CXR) has good sensitivity but poor specificity in TB diagnosis. Xpert MTB/RIF (Mycobacterium tuberculosis/Rifampicin) is increasingly used in many countries as the initial diagnostic test for TB. The aim of the present study was to evaluate the association of radiological findings with the Xpert MTB/RIF test in patients with suspected pulmonary TB. Cross-sectional study in an outpatient TB clinic. Sputum AFB smear, culture, Xpert MTB/RIF, and CXR were collected in patients with suspected pulmonary TB. During the study period, 312 patients met the inclusion criteria and were included in the analysis. Among Xpert MTB/RIF-positive cases, the radiographic patterns were classified as typical of TB, compatible of TB, and normal in 78 (70.3%), 31 (27.9%), and 2 (1.8%) patients, respectively. CXRs were classified as typical of TB, compatible of TB, and normal in 20 (10.0%), 25 (12.4%), and 152 (75.6%) patients, respectively, in Xpert MTB/RIF-negative cases. We found an association between radiographic patterns and Xpert MTB/RIF results in patients with suspected pulmonary TB. These results confirm the current recommended diagnosis algorithm.

Loop-Mediated Isothermal Amplification Assay for Rapid and Reliable Detection of Mycobacterium tuberculosis in Sputum Samples

Introduction: Tuberculosis (TB) remains a major global health problem. The most common method for diagnosing TB in developing countries is sputum smear microscopy; however, the sensitivity of this test is relatively lower. Detection of Mycobacterium tuberculosis using conventional culture and biochemical-based assays is time-consuming and laborious. Polymerase Chain Reaction (PCR) is also available for diagnosis of Mycobacterium tuberculosis. However, the PCR assay requires an expensive thermal cycler to amplify the DNA fragment in multiple temperature-dependent steps. Therefore, a simple and sensitive method for rapid detection has been anxiously awaited. The loop-mediated isothermal amplification (LAMP) assay is a diagnostic technique which can aid in the fight against TB in resource-poor countries. The LAMP assay can amplify a targeted sequence at a constant temperature. Therefore, a large and costly thermal cycler is not necessary for a LAMP assay.Objectives: The objective of this study was to identify Mycobacterium tuberculosis directly from sputum by LAMP and to compare its efficacy over routinely used methods.Methods: A total of 106 (53 fluorochrome staining positive and 53 fluorochrome staining negative) sputum samples were collected in this study. Mycobacterial DNA was extracted from concentrated sputum samples by freezing and boiling method. LAMP assay using a set of six specific primers targeting the M. tuberculosis 16S rRNA gene with high sensitivity was used to analyze sputum samples. The results were then compared with that of the culture method, which was considered as the gold standard method.Results: Among total of 106 samples studied by microscopy and culture, 53 were positive by both, whole four were positive by culture but negative by microscopy. With reference to culture, the microscopy had sensitivity 92.98%, specificity 100%, and predictive value of positive test 100%, predictive value of negative test 92.5%. Out of 106 samples subjected to culture and LAMP for the diagnosis of TB, 55 samples were positive by both tests and two were positive only in culture, while 48 were negative in both tests and one was negative only in culture. While comparing the LAMP with culture as a gold standard, the sensitivity of LAMP was 96.49%, specificity was 97.95%, predictive value of positive test was 98.21%, predictive value of negative test was 96%.Conclusions: Comparative experiments showed that the LAMP assay is a rapid, sensitive, and specific method to detect M. tuberculosis infection. Indeed, an inexpensive LAMP assay would be potential as a diagnostic test for tuberculosis, especially in resource-limited settings. J-GMC-N | Volume 11 | Issue 01 | January-June 2018, Page: 27-34

Variability in distribution and use of tuberculosis diagnostic tests in Kenya: a cross-sectional survey

BackgroundGlobally, 40% of all tuberculosis (TB) cases, 65% paediatric cases and 75% multi-drug resistant TB (MDR-TB) cases are missed due to underreporting and/or under diagnosis. A recent Kenyan TB prevalence survey found that a significant number of TB cases are being missed here. Understanding spatial distribution and patterns of use of TB diagnostic tests as per the guidelines could potentially help improve TB case detection by identifying diagnostic gaps.MethodsWe used 2015 Kenya National TB programme data to map TB case notification rates (CNR) in different counties, linked with their capacity to perform diagnostic tests (chest x-rays, smear microscopy, Xpert MTB/RIF®, culture and line probe assay). We then ran hierarchical regression models for adults and children to specifically establish determinants of use of Xpert® (as per Kenyan guidelines) with county and facility as random effects.ResultsIn 2015, 82,313 TB cases were notified and 7.8% were children. The median CNR/100,000 amongst 0-14yr olds was 37.2 (IQR 20.6, 41.0) and 267.4 (IQR 202.6, 338.1) for ≥15yr olds respectively. 4.8% of child TB cases and 12.2% of adult TB cases had an Xpert® test done, with gaps in guideline adherence. There were 2,072 microscopy sites (mean microscopy density 4.46/100,000); 129 Xpert® sites (mean 0.31/100,000); two TB culture laboratories and 304 chest X-ray facilities (mean 0.74/100,000) with variability in spatial distribution across the 47 counties. Retreatment cases (i.e. failures, relapses/recurrences, defaulters) had the highest odds of getting an Xpert® test compared to new/transfer-in patients (AOR 7.81, 95% CI 7.33-8.33). Children had reduced odds of getting an Xpert® (AOR 0.41, CI 0.36-0.47). HIV-positive individuals had nearly twice the odds of getting an Xpert® test (AOR 1.82, CI 1.73-1.92). Private sector and higher-level hospitals had a tendency towards lower odds of use of Xpert®.ConclusionsWe noted under-use and gaps in guideline adherence for Xpert® especially in children. The under-use despite considerable investment undermines cost-effectiveness of Xpert®. Further research is needed to develop strategies enhancing use of diagnostics, including innovations to improve access (e.g. specimen referral) and overcoming local barriers to adoption of guidelines and technologies.

Use of Interferon-γ release assay for the diagnosis of female genital tuberculosis in Northwest China.

Female genital tuberculosis (FGTB) is one of the major causes of infertility. However, nonspecific manifestations and the lack of easy access to gold-standard diagnostic test render a diagnostic difficult for FGTB. The objective of this study was to determine T-SPOT.TB (an interferon-γ release assay, IGRA) performance in patients with FGTB. A total of 213 female patients with validated T-SPOT.TB results were recruited in this retrospective study. Among which, 103 were confirmed FGTB, and 110 were excluded from tuberculosis (control). Of the confirmed FGTB patients, 52 were confirmed by microbiologically/histopathologically examination, while the remaining 51 were clinically confirmed (successfully responsive to anti-tuberculosis treatment). T-SPOT.TB test was performed in both FGTB and control group during the diagnostic procedure. The overall sensitivity and specificity of T-SPOT.TB were 86.41% and 75.45% respectively. Sensitivity of T-SPOT.TB was significantly higher when compared with conventional tuberculosis diagnostic tests. Moreover, T-SPOT.TB test using pelvic effusion (PE) showed higher sensitivity than using corresponding peripheral blood (PB) (94.44% vs 72.22%, P<0.001). Mean value of spot forming cells (SFCs) of T-SPOT.TB using PE was significantly higher than that of PB in FGTB group (193 (IQR 105-280) SFCs/2.5×105 PEMCs vs 71 (IQR 36-107) SFCs/2.5×105 PBMCs, P=0.01), while this was not detected in control group (11 (IQR 0-22) SFCs/2.5×105 PEMCs vs 9 (IQR 0-18) SFCs/2.5×105 PBMCs, P=0.77). These results demonstrated that T-SPOT.TB, especially PE T-SPOT.TB, is an useful adjunct in FGTB diagnosis.

Internal Medicine Residents' Knowledge and Practice of Pulmonary Tuberculosis Diagnosis.

BackgroundInternal medicine physicians are often the first providers to encounter patients with a new diagnosis of tuberculosis. Given the public health risks of missed tuberculosis cases, assessing internal medicine residents’ ability to diagnose tuberculosis is important.MethodsInternal medicine resident knowledge and practice patterns in pulmonary tuberculosis diagnosis at 7 academic hospitals were assessed utilizing (a) a 10-item validated pulmonary tuberculosis diagnosis assessment tool and (b) a retrospective chart review of 343 patients who underwent a pulmonary tuberculosis evaluation while admitted to a resident-staffed internal medicine or infectious disease service. Our primary outcomes were the mean score and percentage of correct responses per assessment tool question, and the percentage of patients who had Centers for Disease Control and Prevention–recommended tuberculosis diagnostic tests obtained.ResultsOf the 886 residents who received the assessment, 541 responded, yielding a response rate of 61%. The mean score on the assessment tool (SD) was 4.4 (1.6), and the correct response rate was 57% (311/541) or less on 9 of 10 questions. On chart review, each recommended test was obtained for ≤43% (148/343) of patients, other than chest x-ray (328/343; 96%). A nucleic acid amplification test was obtained for 18% (62/343) of patients, whereas 24% (83/343) had only 1 respiratory sample obtained. Twenty patients were diagnosed with tuberculosis.ConclusionsSignificant knowledge and practice gaps exist in internal medicine residents’ abilities to diagnose tuberculosis. As residents represent the future providers who will be evaluating patients with possible tuberculosis, such deficiencies must be addressed.

Temporal analysis of the interference caused by paratuberculosis vaccination on the tuberculosis diagnostic tests in goats

Vaccination against paratuberculosis (PTB) in goats is a cost-effective control strategy, and is also effective as regards preventing the onset of clinical cases. However, it causes interference in the diagnostic tests used in the control of tuberculosis (TB). A group of 99 goats from a herd with no history of TB or PTB infection was vaccinated against PTB at seven months of age. They then underwent consecutive intradermal tests [single (SIT) and comparative (CIT) intradermal tuberculin tests), interferon-gamma release assays (IGRA) and two serological tests (p22_CE and DR-ELISA) every three months, until the interference disappeared. When using the SIT test, a variable number of positive reactors were observed at 3 months (T3; 32.3%, 95% CI 23.9–42.1), 6 months (T6; 11.5%, 95% CI 6.5–19.4), 9 months (T9; 6.4%, 95% CI 3.0–13.2) and 12 months (T12; 0%, 95% CI 0–4.0) post-vaccination. In contrast, the CIT test had a specificity (Sp) of 100% (95%, CI 96.0–100, regardless of the time post-vaccination. The IGRA also obtained high Sp values throughout the study period. No significant interference in the serological tests was recorded at T3 [p22_CE, Sp = 96% (95% CI 90.1–98.4) and DR-ELISA, Sp = 98% (95% CI 92.9–99.4)], although an increase in antibody titers was observed in the following herd testing events. In conclusion, the use of the SIT test causes the onset of false-positive reactors if applied before 12 months post-vaccination in a TB-free/PTB-vaccinated herd. Nevertheless, the CIT test and IGRA obtained high Sp values under these epidemiological circumstances. The serological tests were also highly specific in the case of PTB-vaccinated goats, although their Sp decreased significantly after several intradermal tests.

The utility of repeat Xpert MTB/RIF testing to diagnose tuberculosis in HIV-positive adults with initial negative result.

Background: Amongst HIV-positive adults in South Africa with initial negative Xpert results, we compared the yield from repeating Xpert MTB/RIF ("Xpert") on sputum to guideline-recommended investigation for tuberculosis (TB). Methods: A systematic sample of adults attending for HIV care were enrolled in a cohort exploring TB investigation pathways. This substudy was restricted to those at highest risk of TB (CD4<200 cells/mm 3 or unknown) who had a negative initial Xpert result. At attendance for the Xpert result, a repeat sputum sample was stored, and further investigations facilitated per national guidelines. Participants were reviewed monthly, with reinvestigation if indicated, for at least three months, when sputum and blood were cultured for mycobacteria, and the stored sputum tested using Xpert. We defined TB as "confirmed" if Xpert, line probe assay or Mycobacterium tuberculosis culture within six months of enrolment were positive, and "clinical" if TB treatment was started without microbiological confirmation. Results: Amongst 227 participants with an initial negative Xpert result (63% female, median age 37 years, median CD4 count 100 cells/mm 3), 28 (12%) participants had TB diagnosed during study follow-up (16 confirmed, 12 clinical); stored sputum tested positive on Xpert in 5/227 (2%). Amongst 27 participants who started TB treatment, the basis was bacteriological confirmation 11/27 (41%); compatible imaging 11/27 (41%); compatible symptoms 2/27 (7%); and unknown 3/27 (11%). Conclusions: Amongst HIV-positive individuals at high risk of active TB with a negative Xpert result, further investigation using appropriate diagnostic modalities is more likely to lead to TB treatment than immediately repeating sputum for Xpert. TB diagnostic tests with improved sensitivity are needed.

Empiric tuberculosis treatment in South African primary health care facilities - for whom, where, when and why: Implications for the development of tuberculosis diagnostic tests.

BackgroundThe extent and circumstances under which empiric tuberculosis (TB) treatment (treatment without microbiological confirmation at treatment initiation) is administered in primary health care settings in South Africa are not well described.MethodsWe used data from a pragmatic evaluation of Xpert MTB/RIF in which persons undergoing TB investigations by PHC nurses were followed for six months. Following Xpert or smear-microscopy at enrolment, investigations for tuberculosis were undertaken at the discretion of health care workers. We identified persons whose TB treatment was initiated empirically (no microbiological confirmation at time of treatment initiation at a primary health care facility) and describe pathways to treatment initiation.ResultsOf 4665 evaluable participants, 541 persons were initiated on treatment of whom 167 (31%) had negative sputum tests at enrolment. Amongst these 167, the median number of participant visits to health care providers prior to treatment initiation was 3 (interquartile range [IQR] 2–4). Chest radiography, sputum culture or hospital referral was done in 106/167 (63%). Reasons for TB treatment start were: 1) empiric (n = 82, 49%); 2) a positive laboratory test (n = 49, 29%); 3) referral and treatment start at a higher level of care (n = 28, 17%); and 4) indeterminable (n = 8, 5%). Empiric treatment accounted for 15% (82/541) of all TB treatment initiations and 1.7% (82/4665) of all persons undergoing TB investigations. Chest radiography findings compatible with TB (63/82 [77%]) were the basis for treatment initiation amongst the majority of empirically treated participants. Microbiological confirmation of TB was subsequently obtained for 11/82 (13%) empirically-treated participants. Median time to empiric treatment start was 3.9 weeks (IQR 1.4–11 weeks) after enrolment.ConclusionUncommon prescription of empiric TB treatment with reliance on chest radiography in a nurse-managed programme underscores the need for highly sensitive TB diagnostics suitable for point-of-care, and strong health systems to support TB diagnosis in this setting.

Recent Development in the Molecular Diagnosis of Tuberculosis

ABSTRACT Molecular diagnostic tests are the molecular techniques used to detect a nucleic acid of organisms. They have revolutionized the diagnosis of tuberculosis (TB) and drug resistance. Cartridge-based nucleic acid amplification tests (CBNAAT) and line probe assay (LPA) have been accepted in our national tuberculosis control program. CBNAAT has the advantage that it can be done from crude samples and smear negative samples and results can be obtained by 2 hours. But CBNAAT can detect rifampicin resistance only. On the contrary, LPA can detect rifampicin and isoniazid resistance, but the test can only be done at regional or national levels. LPA cannot be done from smear negative or crude specimens. The recent version of LPA (version 2.0) can overcome that problem. Second line LPA can detect the drug resistance against fluoroquinolones, second line injectable drugs and ethambutol (in version 1.0 only). GeneXpert Omni is a portable technique having 4-hour lasting battery using the same cartridge. GeneXpert Ultra has more sensitivity due to larger chamber size and due to two additional probes. Ultra may replace Xpert soon as it will be more effective against smear-negative TB, TB in HIV positive persons, childhood TB, and extrapulmonary TB. With the introduction of molecular diagnostic tests for TB, we will be able to reduce the time of diagnosis of TB and drug resistance. Thereby, we will be able to start first line or second line anti-tubercular chemotherapy earlier, and that will help us to achieve our goal in controlling TB.

Deconvolution of the Response to Bacillus Calmette-Guérin Reveals NF-κB-Induced Cytokines As Autocrine Mediators of Innate Immunity.

Bacillus Calmette–Guérin (BCG) is used as a vaccine and diagnostic test for tuberculosis, as well as immunotherapy in the treatment of bladder cancer. While clinically useful, the response to mycobacterial stimulation is complex and the induced protein signature remains poorly defined. We characterized the cell types directly engaged by BCG, as well as the induced cytokine loops that transmit signal(s) to bystander cells. Standardized whole-blood stimulations and mechanistic studies on single and purified cell populations identified distinct patterns of activation in monocytes as compared to neutrophils and invariant lymphocyte populations. Deconvoluting the role of Toll-like receptor 2/4 and Dectin-1/2 in the inflammatory response to BCG, we revealed Dectin-1/2 as dominant in neutrophils as compared to monocytes, which equally engaged both pathways. Furthermore, we quantified the role of NF-κB and NADPH/reactive oxygen species (ROS)-dependent cytokines, which triggered a JAK1/2-dependent amplification loop and accounted for 40–50% of the induced response to BCG. In sum, this study provides new insight into the molecular and cellular pathways involved in the response to BCG, establishing the basis for a new generation of immunodiagnostic tools.

Liquid-Crystal-Based Immunosensor for Diagnosis of Tuberculosis in Clinical Specimens.

Tuberculosis (TB) is a serious global health problem, although it is easily preventable and curable. The prevalence of TB is caused by a lack of simple, rapid, cheap, and effective TB diagnostic tests. In this study, we have established a novel liquid crystal (LC)-based immunosensor to diagnose TB in clinical specimens. The clinical serum samples were incubated on a TB antigen-immobilized substrate, and their optical LC responses were observed using a polarized light microscope. Specific binding of anti-TB antibodies to the TB antigen-immobilized surface only occurred in clinical specimens from TB patients, inducing the disruption of the orientation of LCs. This was followed by the distinctive change in the optical appearance of LCs from uniform to random. However, when clinical serum samples from healthy people or latent TB patients were incubated, the orientation of LCs remained uniform. Through the change of optical LC images, in 76% of TB patients, this essay correctly identified the patients as having antibodies to TB in their serums. 91% of healthy people free of TB were correctly identified as not having antibodies to TB. Thus, this LC-based immunosensor is a promising platform, particularly in clinical TB diagnostics, which does not require complicated preparation of clinical specimens or complex instrumentation.

Evaluation of the Mean Cost and Activity Based Cost in the Diagnosis of Pulmonary Tuberculosis in the Laboratory Routine of a High-Complexity Hospital in Brazil.

At a global level, with the increase in healthcare costs, there is a need to assess the economic impact of the incorporation of new technologies in different health disorders in different countries. There is scarce information regarding costs incurred with the use of current or new diagnostic tests for tuberculosis or from the vantage point of their incorporation within the healthcare systems of high-burden countries. The present study aimed to assess the mean cost and the activity based cost of the laboratory diagnosis for tuberculosis by means of conventional techniques and from the Detect TB®LabTest molecular test kit in a general high-complexity hospital of the public health system in Brazil. Cost analysis was performed by means of primary data, collected in the Mycobacteria and Molecular Biology Laboratory in 2013. The mean cost and activity based cost were, respectively, U$10.06/U$5.61 for centrifuged bacilloscopy by Ziehl Neelsen (ZN) and Auramine (AU); U$7.42/U$4.15 for direct bacilloscopy by ZN; U$27.38/U$16.50 for culture in a Loweinstein-Jensen solid medium; and U$115.74/U$73.46 for the Detect TB®LabTest Kit. The calculation of the ABC should be used in making decisions by administrators to be the best method of assessing the costs of conventional techniques and molecular method for providing the real value of the tests. So it is need to calculate the ABC, and not of the mean cost, in various scenarios before incorporating new technologies in health institutions.