Performance of the 2007 WHO algorithm to diagnose smear-negative pulmonary tuberculosis in a HIV prevalent setting

Detection of Mycobacterium tuberculosis transrenal DNA in urine samples among adults in Peru

Diagnosis of pulmonary tuberculosis (TB) relies on a sputum sample, which cannot be obtained from all symptomatic individuals. Mycobacterium tuberculosis (Mtb) transrenal DNA (trDNA) has been detected in urine, an easily obtainable, noninvasive, alternative sample type. However, reported sensitivities have been variable and likely depend on collection and assay procedures and aspects of trDNA biology. We analyzed three serial urine samples from each of 75 adults with culture-confirmed pulmonary TB disease in Lima, Peru for detection of trDNA using short-fragment real-time PCR. Additionally, we examined host, urine, and sampling factors associated with detection. Overall per-sample sensitivity was 38 % (95 % Confidence Interval [CI] 30-45 %). On an individual level (i.e., any of the three samples positive), sensitivity was 73 % (95 % CI: 62-83 %). Sensitivity was highest among samples from patients with smear-positive TB, 92 % (95 % CI: 62-100 %). Specificity from a single sample from each of 10 healthy controls was 100 % (95 % CI: 69-100 %). Adjusting our assay positivity threshold increased individual-level sensitivity to 88 % (95 % CI: 78-94 %) overall without affecting the specificity. We did not find associations between Mtb trDNA detection and individual characteristics or urine sample characteristics. Overall, our results support the potential of trDNA detection for TB diagnosis.

Factors associated with tuberculosis treatment initiation among bacteriologically negative individuals evaluated for tuberculosis: an individual patient data meta-analysis

Background

Globally, over one-third of pulmonary tuberculosis (TB) disease diagnoses are made based on clinical criteria after a negative diagnostic test result. Understanding factors associated with clinicians' decisions to initiate treatment for individuals with negative test results is critical for predicting the potential impact of new diagnostics.

Methods

We performed a systematic review and individual patient data meta-analysis using studies conducted between January/2010 and December/2022 (PROSPERO: CRD42022287613). We included trials or cohort studies that enrolled individuals evaluated for TB in routine settings. In these studies participants were evaluated based on clinical examination and routinely-used diagnostics, and were followed for ≥1 week after the initial test result. We used hierarchical Bayesian logistic regression to identify factors associated with treatment initiation following a negative result on an initial bacteriological test (e.g., sputum smear microscopy, Xpert MTB/RIF).

Findings

Multiple factors were positively associated with treatment initiation: male sex [adjusted Odds Ratio (aOR) 1.61 (1.31-1.95)], history of prior TB [aOR 1.36 (1.06-1.73)], reported cough [aOR 4.62 (3.42-6.27)], reported night sweats [aOR 1.50 (1.21-1.90)], and having HIV infection but not on ART [aOR 1.68 (1.23-2.32)]. Treatment initiation was substantially less likely for individuals testing negative with Xpert [aOR 0.77 (0.62-0.96)] compared to smear microscopy and declined in more recent years.

Interpretation

Multiple factors influenced decisions to initiate TB treatment despite negative test results. Clinicians were substantially less likely to treat in the absence of a positive test result when using more sensitive, PCR-based diagnostics.

Detection of Mycobacterium tuberculosis transrenal DNA in urine samples among adult patients in Peru

Diagnosis of tuberculosis (TB) relies on a sputum sample, which cannot be obtained from all symptomatic patients. Mycobacterium tuberculosis (Mtb) transrenal DNA (trDNA) has been detected in urine, an easily obtainable, noninvasive, alternative sample type. However, reported sensitivities have been variable and likely depend on collection/assay procedures and aspects of trDNA biology. We analyzed three serial urine samples from each of 75 adults with culture-confirmed pulmonary TB disease in Lima, Peru for detection of trDNA using short-fragment real-time PCR. Additionally, we examined host, urine, and sampling factors associated with detection. Overall sample sensitivity was 38% (95% Confidence Interval [CI] 30-45%). On a patient level (i.e., any of three samples positive), sensitivity was 73% (95% CI: 62-83%). Sensitivity was highest among samples from patients with smear-positive TB, 92% (95% CI: 62-100%). Specificity from a single sample from each of 10 healthy controls was 100% (95% CI: 69-100%). Adjusting our assay positivity threshold increased patient-level sensitivity to 88% (95% CI: 78-94%) overall without affecting the specificity. We did not find associations between Mtb trDNA detection and either patient characteristics or urine sample characteristics. Overall, our results support the potential of trDNA detection for TB diagnosis.

Patients with presumed tuberculosis in sub-Saharan Africa that are not diagnosed with tuberculosis: a systematic review and meta-analysis

BACKGROUND

Many patients in sub-Saharan Africa whom a diagnosis of tuberculosis is considered are subsequently not diagnosed with tuberculosis. The proportion of patients this represents, and their alternative diagnoses, have not previously been systematically reviewed.

METHODS

We searched four databases from inception to 27 April 2020, without language restrictions. We included all adult pulmonary tuberculosis diagnostic studies from sub-Saharan Africa, excluding case series and inpatient studies. We extracted the proportion of patients with presumed tuberculosis subsequently not diagnosed with tuberculosis and any alternative diagnoses received. We conducted a random effects meta-analysis to obtain pooled estimates stratified by passive and active case finding.

RESULTS

Our search identified 1799 studies, of which 18 studies (2002-2019) with 14 527 participants from 10 African countries were included. The proportion of patients with presumed tuberculosis subsequently not diagnosed with tuberculosis was 48.5% (95% CI 39.0 to 58.0) in passive and 92.8% (95% CI 85.0 to 96.7) in active case-finding studies. This proportion increased with declining numbers of clinically diagnosed tuberculosis cases. A history of tuberculosis was documented in 55% of studies, with just five out of 18 reporting any alternative diagnoses.

DISCUSSION

Nearly half of all patients with presumed tuberculosis in sub-Saharan Africa do not have a final diagnosis of active tuberculosis. This proportion may be higher when active case-finding strategies are used. Little is known about the healthcare needs of these patients. Research is required to better characterise these patient populations and plan health system solutions that meet their needs.

PROSPERO REGISTRATION NUMBER

CRD42018100004.

Utility of broad-spectrum antibiotics for diagnosing pulmonary tuberculosis in adults: a systematic review and meta-analysis

BACKGROUND

Suboptimal diagnostics for pulmonary tuberculosis drive the use of the so-called trial of antibiotics, a course of broad-spectrum antibiotics without activity against Mycobacterium tuberculosis that is given to patients who are mycobacteriology negative but symptomatic, with the aim of distinguishing pulmonary tuberculosis from bacterial lower respiratory tract infection. The underlying assumption-that patients with lower respiratory tract infection will improve, whereas those with pulmonary tuberculosis will not-has an unclear evidence base for such a widely used intervention (at least 26·5 million courses are prescribed per year). We aimed to collate available evidence on the diagnostic performance of the trial of antibiotics.

METHODS

In this systematic review and meta-analysis we searched the MEDLINE, Embase, and Global Health databases for studies published up to March 15, 2019, that investigated the sensitivity and specificity of the trial of antibiotics against mycobacteriology tests in adults (≥15 years) with tuberculosis symptoms. We used the QUADAS-2 tool to assess the risk of bias. We estimated pooled values for sensitivity and specificity of trial of antibiotics (as the index text) versus mycobacteriology tests (as the reference standard) using random-effects bivariate modelling, and we used the I² statistic to assess heterogeneity between studies contributing to these estimates. This study is registered with PROSPERO, number CRD42017083915.

FINDINGS

Of the 9410 articles identified by our search, eight studies were eligible for inclusion. The studies were from seven countries in Africa, South America, and Asia, and involved 2786 participants. Six studies used mycobacterial culture as the reference standard, and six used penicillins for the trial of antibiotics. The treatment duration, number of antimicrobial courses, and definition of what constituted response to treatment varied substantially between studies. The pooled sensitivity (67%, 95% CI 42-85) and specificity (73%, 58-85) of the trial of antibiotics versus mycobacteriology tests were below internationally defined minimum performance profiles for tuberculosis diagnostics and had substantial heterogeneity (I² was 96% for sensitivity and 99% for specificity). Each included study failed on one or more domain of the QUADAS-2 tool.

INTERPRETATION

Current policy and practice regarding the trial of antibiotics appear inappropriate, given the weak evidence base, poor diagnostic performance, potential contribution to the global antimicrobial resistance crisis, and adverse individual and public health consequences from the misclassification of tuberculosis status. Antibiotic strategies during tuberculosis investigations should instead optimise clinical outcomes, ideally guided by clinical trials in both inpatient and outpatient groups.

FUNDING

Helse Nord RHF, Wellcome Trust, and the UK Commonwealth Scholarship Commission.

A Clinical Prediction Score Including Trial of Antibiotics and C-Reactive Protein to Improve the Diagnosis of Tuberculosis in Ambulatory People With HIV

Background

The use of a “trial of antibiotics” as empiric therapy for bacterial pneumonia as a diagnostic tool for tuberculosis in people with HIV (PWH) was removed from World Health Organization (WHO) recommendations in 2007, based on expert opinion. Current guidelines recommend antibiotics only after 2 Xpert MTB/RIF tests (if available), chest x-ray, and clinical assessment have suggested that tuberculosis is unlikely. Despite this, a “trial of antibiotics” remains common in algorithms in low-resource settings, but its value is uncertain. C-reactive protein (CRP), which has been proposed as a “rule-out” test for tuberculosis, may be an objective marker of response to antibiotics.

Methods

We performed a passive case-finding cohort study of adult PWH with a positive WHO symptom screen. All participants received antibiotics at first visit according to the local protocol and were reviewed to ascertain clinical response. Point-of-care CRP was measured at both visits. All patients had sputum tested with Xpert MTB/RIF Ultra (Ultra), and the reference standard was based on 2 sputum mycobacterial cultures. We explored multivariable prediction models (MPM) for tuberculosis based on 1 or 2 visits.

Results

Seventy-five of 207 patients (36%) had confirmed tuberculosis. Clinical response to antibiotics after 2 days was a good predictor of disease. An MPM based on 2 visits, without CRP, had acceptable discrimination (c-statistic, 0.75) and calibration (goodness-of-fit P = .07). Addition of CRP after antibiotics improved the model moderately (c-statistic, 0.78). CRP at first visit was not an independent predictor of tuberculosis.

Conclusions

In adult PWH seeking care for symptoms suggestive of tuberculosis, lack of response to antibiotics is a strong predictor of disease and is likely to be useful, particularly when access to Ultra is limited. CRP adds value when measured after antibiotics but is of limited value at first visit.

Mortality in the first six months among HIV-positive and HIV-negative patients empirically treated for tuberculosis

Background

Empirical treatment of tuberculosis (TB) may be necessary in patients with negative or no Xpert MTB/RIF results. In a context with access to Xpert, we assessed mortality in the 6 months after the initial TB consultation among HIV-positive and HIV-negative patients who received empirical TB treatment or TB treatment based on bacteriological confirmation and we compared it with the mortality among those who did not receive TB treatment.

Methods

This prospective cohort study included consecutively adult patients with signs and symptoms of TB attending an outpatient TB clinic in Western Kenya. At the first consultation, patients received a clinical exam and chest X-ray. Sputum was collected for microscopy, Xpert and Mycobacterium tuberculosis complex (MTB) culture. Patients not started on TB treatment were reassessed after 5 days. All patients bacteriologically confirmed (positive Xpert or culture) received TB treatment. Empirical treatment was defined as a decision to start TB treatment without bacteriological confirmation. Patients were reassessed after 6 months.

Results

Of 606 patients included, 344/606 (56.8%) were women. Median age was 35 years [Interquartile Range (IQR):27–47] and 398/594 (67.0%) were HIV-positive. In total, 196/606 (32.3%) patients were Xpert- or culture-positive and 331/606 (54.6%) started TB treatment. Overall, 100/398 (25.1%) HIV-positive and 31/196 (15.8%) HIV-negative patients received empirical treatment. Mortality in the 6 months following the first consultation was 1.6 and 0.8/100 patient-months among HIV-positive and HIV-negative patients respectively. In the multivariate analyses, TB treatment - whether empirical or based on bacteriological confirmation- was not associated with increased mortality among HIV-positive patients (aHR:2.51, 95%CI:0.79–7.90 and aHR:1.25, 95%CI:0.37–4.21 respectively). However, HIV-negative patients who received empirical treatment had a higher risk of mortality (aHR:4.85, 95%CI:1.08–21.67) compared to those not started on treatment. HIV-negative patients treated for TB based on bacteriological confirmation did not have a different risk of mortality (aHR:0.77, 95%CI:0.08–7.41).

Conclusions

Our findings suggest that in a context with access to Xpert, clinicians should continue using empirical TB treatment in HIV-positive patients with signs and symptoms of TB and negative Xpert results. However, differential diagnoses other than TB should be actively sought before initiating empirical TB treatment, particularly in HIV-negative patients.

Active and latent tuberculosis among inmates in La Esperanza prison in Guaduas, Colombia

Introduction

Active tuberculosis (TB) and latent tuberculosis infection (LTBI) are a public health threat in prisons around the world. The objectives of the study were to estimate the prevalence of LTBI and TB as well as to investigate TB transmission inside one prison, in Colombia.

Methods

A Cross-sectional study was conducted in inmates who agreed to participate. Inmates with respiratory symptoms (RS) of any duration underwent to medical evaluation and three sputum samples were taken for smear microscopy and culture for TB diagnosis. Drug susceptibility was analyzed using BACTEC MGIT 960 and GenoType MTBDRplus. Molecular genotyping of Mycobacterium tuberculosis isolates was performed by 24-Locus MIRU-VNTR and spoligotyping. LTBI was evaluated according to the result of the tuberculin skin test (TST). Close contact investigation was conducted inside the prison for inmates that shared the cell with the index TB case.

Results

Among 301/2,020 (15%) inmates with RS of any duration, 8% were diagnosed with active TB. The prevalence of active TB was 1,026 cases/100,000 inmates. We isolated M. tuberculosis in 19/24 (79%) TB cases, 94.7% were susceptible to first line drugs and only one was monoresistant to isoniazid. The most prevalent sub-lineage was Haarlem (68.4%), followed by LAM (26.3%) and T superfamily (5.3%). 24-Locus MIRU-VNTR typing results alone or in combination with spoligotyping identified three clusters containing two isolates each. Two clusters corresponded to inmates that shared the same cell, but each one was located in different blocks of the prison. Inmates from the last cluster were in the same block in nearby cells. TST reading was performed in 95.6% inmates, and 67.6% had a positive reaction.

Conclusions

The prevalence of LTBI and TB was higher in prison than in the general population. Molecular genotyping suggests that TB in this prison is mainly caused by strains imported by inmates or endogenous reactivation.

Empiric TB Treatment of Severely Ill Patients With HIV and Presumed Pulmonary TB Improves Survival

RATIONALE

In 2007, World Health Organization (WHO) issued emergency recommendations on empiric treatment of sputum acid-fast bacillus smear-negative patients with possible tuberculosis (TB) in HIV-prevalent areas, and called for operational research to evaluate their effectiveness. We sought to determine if early, empiric TB treatment of possible TB patients with abnormal chest radiography or severe illness as suggested by the 2007 WHO guidelines, is associated with improved survival.

METHODS

We prospectively enrolled consecutive HIV-seropositive inpatients at Mulago Hospital in Kampala, Uganda, from 2007 to 2011 with cough for ≥2 weeks. We retrospectively examined the effect of empiric TB treatment before discharge on 8-week survival among those with and without a WHO-defined "danger sign," including fever >39°C, tachycardia >120 beats per minute, or tachypnea >30 breaths per minute. We modeled the interaction between empiric TB treatment and danger signs, and their combined effect on 8-week survival, and adjusted for relevant covariates.

RESULTS

Among 631 sputum smear-negative patients, 322 (51%) had danger signs. Cumulative 8-week survival of patients with danger signs was significantly higher with empiric TB treatment (80%) than without treatment (64%, P < 0.001). After adjusting for duration of cough and concurrent hypoxemia, patients with danger signs who received empiric TB treatment had a 44% reduction in 8-week mortality (risk ratio 0.56, 95% confidence interval: 0.34-0.91, P = 0.020).

CONCLUSIONS

Empiric TB treatment of HIV-seropositive, smear-negative, presumed pulmonary TB patients with 1 or more danger signs is associated with improved 8-week survival. Enhanced implementation of the 2007 WHO empiric treatment recommendations should be encouraged whenever and wherever rapid and highly sensitive diagnostic tests for TB are unavailable.

Cost-effectiveness analysis of microscopic observation drug susceptibility test versus Xpert MTB/Rif test for diagnosis of pulmonary tuberculosis in HIV patients in Uganda

BACKGROUND

Microscopic Observation Drug Susceptibility (MODS) and Xpert MTB/Rif (Xpert) are highly sensitive tests for diagnosis of pulmonary tuberculosis (PTB). This study evaluated the cost effectiveness of utilizing MODS versus Xpert for diagnosis of active pulmonary TB in HIV infected patients in Uganda.

METHODS

A decision analysis model comparing MODS versus Xpert for TB diagnosis was used. Costs were estimated by measuring and valuing relevant resources required to perform the MODS and Xpert tests. Diagnostic accuracy data of the tests were obtained from systematic reviews involving HIV infected patients. We calculated base values for unit costs and varied several assumptions to obtain the range estimates. Cost effectiveness was expressed as costs per TB patient diagnosed for each of the two diagnostic strategies. Base case analysis was performed using the base estimates for unit cost and diagnostic accuracy of the tests. Sensitivity analysis was performed using a range of value estimates for resources, prevalence, number of tests and diagnostic accuracy.

RESULTS

The unit cost of MODS was US$ 6.53 versus US$ 12.41 of Xpert. Consumables accounted for 59 % (US$ 3.84 of 6.53) of the unit cost for MODS and 84 % (US$10.37 of 12.41) of the unit cost for Xpert. The cost effectiveness ratio of the algorithm using MODS was US$ 34 per TB patient diagnosed compared to US$ 71 of the algorithm using Xpert. The algorithm using MODS was more cost-effective compared to the algorithm using Xpert for a wide range of different values of accuracy, cost and TB prevalence. The cost (threshold value), where the algorithm using Xpert was optimal over the algorithm using MODS was US$ 5.92.

CONCLUSIONS

MODS versus Xpert was more cost-effective for the diagnosis of PTB among HIV patients in our setting. Efforts to scale-up MODS therefore need to be explored. However, since other non-economic factors may still favour the use of Xpert, the current cost of the Xpert cartridge still needs to be reduced further by more than half, in order to make it economically competitive with MODS.

Outcomes of a clinical diagnostic algorithm for management of ambulatory smear and Xpert MTB/Rif negative HIV infected patients with presumptive pulmonary TB in Uganda: a prospective study

Introduction

Diagnostic guidelines for Tuberculosis (TB) in HIV infected patients previously relied on microscopy where the value of initial antibiotic treatment for exclusion of pulmonary TB (PTB) was limited. New guidelines rely on the Xpert MTB Rif test (Xpert). However, the value of the antibiotic treatment remains unclear particularly in individuals who are smear-negative and Xpert-negative-given Xpert has only moderate sensitivity for smear-negative PTB. We assessed an algorithm involving initial treatment with antibiotics prior empiric TB treatment in HIV patients with presumptive PTB who were both smear and Xpert negative.

Methods

We performed a prospective study with six month follow-up to establish patient response to a course of broad spectrum antibiotics prior empiric TB treatment between March 2012 and June 2013. We calculated the proportion of patients who responded to the antibiotic treatment and those who did not. We computed the crude and adjusted odds ratios with their 95% confidence intervals, for response to the antibiotic treatment on various patient characteristics. We report treatment outcomes for patients who received broad spectrum antibiotics only or who were initiated empiric TB treatment.

Results

Our cohort comprised 162 smear-negative and Xpert-negative patients, of whom 59% (96 of 162) were female, 81% (131 of 162) were on antiretroviral therapy (ART) for a median of 8.7 months. Overall, 88% (141 of 160) responded to the antibiotic treatment, 8% (12 of 160) got empiric TB treatment and 4% (7 out of 160) were treated for other respiratory disease. The odds of improvement on antibiotics were lower in patients with advanced HIV disease than in patients with early HIV disease. Adjusted odds ratios were significant for HIV clinical stage (AOR; 0.038,) and duration on ART (AOR; 1.038,).

Conclusion

The majority of HIV patients with presumptive PTB with smear-negative and Xpert negative results improved on the antibiotic treatment and did not require empiric TB treatment. Initial antibiotic treatment appeared more successful in patients with less advanced HIV disease. Findings from our study suggest it is useful to initiate HIV infected patients with presumptive PTB having smear and Xpert negative results on an initial course of antibiotic treatment prior empiric TB treatment.

Predictors for MTB Culture-Positivity among HIV-Infected Smear-Negative Presumptive Tuberculosis Patients in Uganda: Application of New Tuberculosis Diagnostic Technology

Background

The existing World Health Organization diagnostic algorithms for smear-negative TB perform poorly in HIV-infected individuals. New TB diagnostics such as urine TB lipoarabinomannan (LAM) could improve the accuracy and reduce delays in TB diagnosis in HIV-infected smear-negative presumptive TB. We sought to determine predictors for MTB culture-positivity among these patients.

Methods

This study was nested into a prospective evaluation of HIV-infected outpatients and inpatients clinically suspected to have TB who were screened by smear-microscopy on two spot sputum samples. Data on socio-demographics, clinical symptoms, antiretroviral therapy, CXR, CD4 count, mycobacterial sputum and blood cultures and TB-LAM were collected. Logistic regression and conditional inference tree analysis were used to determine the most predictive indicators for MTB culture-positivity.

Results

Of the 418 smear-negative participants [female, 64%; median age (IQR) 32 (28-39) years, median CD4 106 (IQR 22 - 298) cells/mm³], 96/418 (23%) were sputum and/ or blood culture-positive for Mycobacterium tuberculosis (MTB) complex. Abnormal CXR (aOR 3.68, 95% CI 1.76- 7.71, p=0.001) and positive urine TB-LAM (aOR 6.21, 95% CI 3.14-12.27, p< 0.001) were significantly associated with MTB culture-positivity. Previous TB treatment (aOR 0.41, 95% CI 0.17-0.99, p=0.049) reduced the likelihood of a positive MTB culture. A conditional inference tree analysis showed that positive urine TB-LAM and abnormal CXR were the most predictive indicators of MTB culture-positivity. A combination of urine TB-LAM test and CXR had sensitivity and specificity of 50% and 86.1% respectively overall, and 70.8% and 84.1% respectively among those with CD4<100 cells/mm³.

Conclusions

A positive urine TB-LAM test and an abnormal CXR significantly predict MTB culture-positivity among smear-negative HIV-infected presumptive TB patients while previous TB treatment reduces the likelihood of a positive MTB culture. Validation studies to assess the performance of diagnostic algorithms that include urine TB-LAM in the diagnosis of smear-negative TB in HIV-infected individuals are warranted.

Impact of mycobacterial culture among HIV-infected adults with presumed TB in Uganda: a prospective cohort study

BACKGROUND

Implementation of new tuberculosis (TB) diagnostic strategies in resource-constrained settings is challenging. We measured the impact of solid and liquid mycobacterial cultures on treatment practices for patients undergoing TB evaluation in Kampala, Uganda.

METHODS

We enrolled consecutive smear-negative, human immunodeficiency virus positive adults with cough of ⩾2 weeks from September 2009 to April 2010. Laboratory technicians performed mycobacterial cultures on solid and liquid media. We compared empiric treatment decisions with solid and liquid culture in terms of diagnostic yield and time to results, and assessed impact on patient management.

RESULTS

Of 200 patients enrolled, 26 (13%) had culture-confirmed TB: 22 (85%) on solid culture alone, 2 (8%) on liquid culture alone, and 2 (8%) on both solid and liquid culture. Thirty-four patients received empiric anti-tuberculosis treatment, but only 10 (29%) were culture-positive. Median time to a positive result on solid culture was 92 days (interquartile range [IQR] 69-148) compared to 106 days (IQR 66-157) for liquid culture. No patients initiated treatment following a positive result on liquid culture.

CONCLUSION

The introduction of mycobacterial culture did not influence care for patients undergoing evaluation for TB in Kampala, Uganda. Attention to contextual factors surrounding implementation is needed to ensure the effective introduction of new testing strategies in low-income countries.

[The role of imaging in thoracic tuberculosis]

Tuberculosis is an infectious disease mostly due to Mycobacterium tuberculosis. It is frequent in developing countries and its incidence is rising in developed countries. Lungs are the most involved organs of the chest but other structures can be affected. Imaging is fundamental in the management of the disease. Confirmation of diagnosis can be made only by bacteriologic and/or histologic exams. The first approach of diagnosis is based on clinical symptoms and chest X-ray signs. Radiologic signs depend on patient's age, his immune status and his previous contact with M. tuberculosis. Conventional chest X-ray remains the first-line exam to realize. It can suggest the diagnosis on the appearance and location of the lesions. CT scan is recommended for the positive diagnosis in case of discrepancy between clinical and radiographic signs, as for the diagnosis of parenchymal, vascular, lymph nodes, pleural, parietal or mediastinal complications. It is also essential for the evaluation of parenchyma sequelae. MRI and PET-scan have limited indications. The purpose of this article is to illustrate different radiological forms of chest tuberculosis, its sequelae and complications and to highlight the role of each imaging technique in the patient's management.

Cost-effectiveness of point-of-care digital chest-x-ray in HIV patients with pulmonary mycobacterial infections in Nigeria

Background

Chest-x-ray is routinely used in the diagnosis of smear negative tuberculosis (TB). This study assesses the incremental cost per true positive test of a point-of-care digital chest-x-ray, in the diagnosis of pulmonary mycobacterial infections among HIV patients with presumed tuberculosis undetected by smear microscopy.

Methods

Consecutive patients with clinical suspicion of pulmonary tuberculosis were serially tested for Human immunodeficiency virus (HIV), their sputum examined for Acid Fast Bacilli then cultured in broth and solid media. Cultures characterized as tuberculous (M.tb) and non-tuberculous (NTM) mycobacteria by Hain assays were used as gold standards. A chest-x-ray was classified as: (1) consistent for TB, (2) not consistent for TB and (3) no pathology.

Results

Of the 1391 suspected cases enrolled, complete data were available for 952 (68%): 753/952 (79%) had negative smear tests while 150/753 (20%) had cultures positive for TB. Of those, 82/150 (55%) had chest-x-ray signs consistent with TB and 29/82 (35%) were positive for HIV. Within the co-infected, 9/29 (31%) had NTM infections. Among all suspects, the cost per positive case detected using smear microscopy test was $52.84; the overall incremental cost per positive case using chest-x-ray in smear negatives was $23.42, and in smear negative, HIV positive patients the cost was $15.77.

Conclusion

Point-of-care chest-x-ray is a cost-effective diagnostic tool for smear negative HIV positive patients with pulmonary mycobacterial infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0675-0) contains supplementary material, which is available to authorized users.

Prevalence of national treatment algorithm defined smear positive pulmonary tuberculosis in HIV positive patients in Brazzaville, Republic of Congo

Background

In the Republic in Congo, the national algorithm for the diagnosis of pulmonary tuberculosis (TB) relies on Ziehl-Neelsen (ZN) sputum smear microscopy, chest X-ray radiography (CXR) and clinical symptoms. Microscopy positive pulmonary TB (MPT+) is defined as symptoms of TB and a positive ZN smear. Microscopy negative pulmonary TB (MPT-) is defined as symptoms of TB, a negative ZN smear but CXR changes consistent with TB. The present cross-sectional study was designed to determine the prevalence of positive and negative MPT individuals among HIV positive and HIV negative individuals presenting to an ambulatory TB treatment center (CTA) in Brazzaville.

Methods

All study participants underwent a physical examination, chest radiography and three ZN sputum smear examinations and HIV testing. Viral load and CD4 counts were determined for HIV positive individuals.

Results

775 individuals presented with symptoms of TB. 425 individuals accepted the voluntary HIV test. 133 (31.3%) were HIV positive (HIV+) and 292 (68.7%) were HIV negative (HIV-). Of the 292 HIV- individuals 167 (57%) were classified as positive MPT and 125 (43%) as negative MPT. Of the 133 HIV positive individuals 39 (29%) were classified as MPT + and 94 (71%) as MPT-.

Conclusion

Our study shows that the prevalence of positive MPT individuals is lower among HIV positive individuals compared to HIV negative individuals in agreement to reports from other countries. The data suggest that a substantial number of HIV positive pulmonary TB cases are not detected by the national algorithm and highlight the need for new diagnostic tests in this population.

A comparison of tools used for tuberculosis diagnosis in resource-limited settings: a case study at Mubende referral hospital, Uganda

Background

This study compared TB diagnostic tools and estimated levels of misdiagnosis in a resource-limited setting. Furthermore, we estimated the diagnostic utility of three-TB-associated predictors in an algorithm with and without Direct Ziehl-Neelsen (DZM).

Materials and Methods

Data was obtained from a cross-sectional study in 2011 conducted at Mubende regional referral hospital in Uganda. An individual was included if they presented with a two weeks persistent cough and or lymphadenitis/abscess. 344 samples were analyzed on DZM in Mubende and compared to duplicates analyzed on direct fluorescent microscopy (DFM), growth on solid and liquid media at Makerere University. Clinical variables from a questionnaire and DZM were used to predict TB status in multivariable logistic and Cox proportional hazard models, while optimization and visualization was done with receiver operating characteristics curve and algorithm-charts in Stata, R and Lucid-Charts respectively.

Results

DZM had a sensitivity and specificity of 36.4% (95% CI = 24.9–49.1) and 97.1%(95% CI = 94.4–98.7) compared to DFM which had a sensitivity and specificity of 80.3%(95% CI = 68.7–89.1) and 97.1%(95% CI = 94.4–98.7) respectively. DZM false negative results were associated with patient’s HIV status, tobacco smoking and extra-pulmonary tuberculosis. One of the false negative cases was infected with multi drug resistant TB (MDR). The three-predictor screening algorithm with and without DZM classified 50% and 33% of the true cases respectively, while the adjusted algorithm with DZM classified 78% of the true cases.

Conclusion

The study supports the concern that using DZM alone risks missing majority of TB cases, in this case we found nearly 60%, of who one was an MDR case. Although adopting DFM would reduce this proportion to 19%, the use of a three-predictor screening algorithm together with DZM was almost as good as DFM alone. It’s utility is whoever subject to HIV screening all TB suspects.

Do high rates of empirical treatment undermine the potential effect of new diagnostic tests for tuberculosis in high-burden settings?

In tuberculosis-endemic settings, patients are often treated empirically, meaning that they are placed on treatment based on clinical symptoms or tests that do not provide a microbiological diagnosis (eg, chest radiography). New tests for tuberculosis, such as the Xpert MTB/RIF assay (Cepheid, Sunnyvale, CA, USA), are being implemented at substantial cost. To inform policy and rationally drive implementation, data are needed for how these tests affect morbidity, mortality, transmission, and population-level tuberculosis burden. If people diagnosed by use of new diagnostics would have received empirical treatment a few days later anyway, then the incremental benefit might be small. Will new diagnostics substantially improve outcomes and disease burden, or simply displace empirical treatment? Will the extent and accuracy of empirical treatment change with the introduction of a new test? In this Personal View, we review emerging data for how empirical treatment is frequently same-day, and might still be the predominant form of treatment in high-burden settings, even after Xpert implementation; and how Xpert might displace so-called true-positive, rather than false-positive, empirical treatment. We suggest types of studies needed to accurately assess the effect of new tuberculosis tests and the role of empirical treatment in real-world settings. Until such questions can be addressed, and empirical treatment is appropriately characterised, we postulate that the estimated population-level effect of new tests such as Xpert might be substantially overestimated.

High incidence of tuberculosis, low sensitivity of current diagnostic scheme and prolonged culture positivity in four colombian prisons. A cohort study

OBJECTIVE

To determine the incidence of pulmonary tuberculosis (TB) in inmates, factors associated with TB, and the time to sputum smear and culture conversion during TB treatment.

METHODS

Prospective cohort study. All prisoners with respiratory symptoms (RS) of any duration were evaluated. After participants signed consent forms, we collected three spontaneous sputum samples on consecutive days. We performed auramine-rhodamine staining, culturing with the thin-layer agar method, Löwestein-Jensen medium and MGIT, susceptibility testing for first-line drugs; and HIV testing. TB cases were followed, and the times to smear and culture conversion to negative were evaluated.

RESULTS

Of 9,507 prisoners held in four prisons between April/30/2010 and April/30/2012, among them 4,463 were screened, 1,305 were evaluated for TB because of the lower RS of any duration, and 72 were diagnosed with TB. The annual incidence was 505 cases/100,000 prisoners. Among TB cases, the median age was 30 years, 25% had <15 days of cough, 12.5% had a history of prior TB, and 40.3% had prior contact with a TB case. TB-HIV coinfection was diagnosed in three cases. History of prior TB, contact with a TB case, and being underweight were risk factors associated with TB. Overweight was a protective factor. Almost a quarter of TB cases were detected only by culture; three cases were isoniazid resistant, and two resistant to streptomycin. The median times to culture conversion was 59 days, and smear conversion was 33.

CONCLUSIONS

The TB incidence in prisons is 20 times higher than in the general Colombian population. TB should be considered in inmates with lower RS of any duration. Our data demonstrate that patients receiving adequate anti-TB treatment remain infectious for prolonged periods. These findings suggest that current recommendations regarding isolation of prisoners with TB should be reconsidered, and suggest the need for mycobacterial cultures during follow-up.

Evaluation of the 2007 WHO guideline to diagnose smear negative tuberculosis in an urban hospital in Ethiopia

Background

The 2007 World Health Organization (WHO) guideline to diagnose smear-negative tuberculosis (TB) in HIV-prevalent settings was mainly based on expert advice and therefore requires evaluation in real life situations.

Methods

In 2009, this guideline was introduced at the ALERT hospital in Ethiopia. From October 2009 to January 2011, the accuracy of the guideline was evaluated using Mycobacterium tuberculosis culture positivity as reference standard in HIV positive TB suspects.

Results

A total of 459 TB suspects were enrolled during the study period; 336 (73.2%) were HIV positive. Acid fast bacilli sputum smear microscopy was done for 74.7% (251/336) HIV positive TB suspects; 94.4% (237/251) were smear negative. A chest X-ray was performed in 92.8% (220/237) and a Mycobacterium tuberculosis culture in 63.7% (151/237). The median TB diagnostic delay for smear negative cases was 3 days (interquartile range 3–4 days). Of the 75 patients diagnosed with smear negative pulmonary TB, 89. 4% (67/75) were diagnosed by chest X-ray, 9.4% (7/75) by culture and 1.3% (1/75) by clinical suspicion only. In 147 smear negative TB suspects Mycobacterium tuberculosis culture and chest X-ray results were available. Among these 147 patients, the sensitivity of the chest X-ray to diagnose smear negative TB in HIV-positive TB suspects was 53.3% (95% CI: 26.7-78.7); the specificity 67.4% (95% CI: 58.7-75.3).

Conclusion

The 2007 WHO diagnostic algorithm for the diagnosis of smear negative TB is likely to reduce the diagnostic delay and therefore decrease morbidity and mortality of TB in a HIV prevalent settings like Ethiopia.

Comparison of two methods for acquisition of sputum samples for diagnosis of suspected tuberculosis in smear-negative or sputum-scarce people: a randomised controlled trial

BACKGROUND

Sputum obtained either under instruction from a health-care worker or through induction can improve case detection of active tuberculosis. However, the best initial sputum sampling strategy for adults with suspected smear-negative or sputum-scarce tuberculosis in primary care is unclear. We compared these two methods of sample acquisition in such patients.

METHODS

In this randomised controlled trial, we enrolled adults (age ≥18 years) with sputum-scarce or smear-negative suspected tuberculosis from three primary care clinics in Cape Town, South Africa. Patients were randomly assigned (1:1) to receive either health-care worker instruction or induction to obtain sputum samples. Neither patients nor investigators were masked to allocation. The primary outcome was the proportion of patients who had started treatment after 8 weeks in a modified intention-to-treat population. Secondary outcomes were proportions starting treatment within different time periods, proportion of patients producing sputum for diagnosis, adverse effects, sputum samples' quality, and case detection by diagnostic method. This study is registered with ClinicalTrials.gov, number NCT01545661.

FINDINGS

We enrolled 481 patients, of whom 213 were assigned to health-care worker instruction versus 268 assigned to induction. The proportion of patients who started treatment in the 8 weeks after enrolment did not differ significantly between groups (53/213 [25%] vs 73/268 [27%]; OR 0·88, 95% CI 0·57-1·36; p=0·56). A higher proportion of instructed versus induced patients initiated empiric treatment based on clinical and radiography findings (32/53 [60%] vs 28/73 [38%]; p=0·015). An adequate sputum sample ≥1 mL was acquired in a lower proportion of instructed versus induced patients (164/213 [77%] vs 238/268 [89%]; p<0·0001), and culture-based diagnostic yield was lower in instructed versus induced patients (24/213 [11%] vs 51/268 [19%]; p=0·020). However, same-day tuberculosis case detection was similar in both groups using either smear microscopy (13/213 [6%] vs 22/268 [8%]; p=0·38) or Xpert-MTB/RIF assay (13/89 [15%] vs 20/138 [14%]; p=0·98). No serious adverse events occurred in either group; side-effects related to sample acquisition were reported in 32 of 268 (12%) patients who had sputum induction and none who had instruction. Cost per procedure was lower for instructed than for induced patients (US$2·14 vs US$7·88).

INTERPRETATION

Although induction provides an adequate sample and a bacteriological diagnosis more frequently than instruction by a health-care worker, it is more costly, does not result in a higher proportion of same-day diagnoses, and-because of widespread empiric treatment-may not result in more patients starting treatment. Thus, health-care worker instruction might be the preferred strategy for initial collection of sputum samples in adults with suspected sputum-scarce or smear-negative tuberculosis in a high burden primary care setting.

FUNDING

South African National Research Foundation, European Commission, National Institutes of Health, European and Developing Countries Clinical Trials Partnership, Discovery Foundation.