Diagnostic accuracy of tongue swab testing on two automated tuberculosis diagnostic platforms, Cepheid Xpert MTB/RIF Ultra and Molbio Truenat MTB Ultima

Tongue dorsum swabbing is a potential alternative to sputum collection for tuberculosis (TB) testing. Previous studies showed that Cepheid Xpert MTB/RIF Ultra (Xpert Ultra) can detect Mycobacterium tuberculosis DNA on tongue swabs stored in buffer, with 72% sensitivity and 100% specificity relative to a sputum microbiological reference standard (sputum MRS). The present study evaluated a more convenient sample collection protocol (dry swab storage), combined with streamlined sample processing protocols, for evaluating two commercial TB diagnostic tests: Xpert Ultra and Molbio Truenat MTB Ultima (MTB Ultima). Copan FLOQSwabs were self-collected or collected by study workers from 321 participants in Western Cape, South Africa. All participants had symptoms suggestive of TB, and 245 of them had sputum MRS-confirmed TB (by sputum MGIT culture and/or Xpert Ultra). One tongue swab per participant was tested on Xpert Ultra, and another tongue swab was tested with MTB Ultima. Xpert Ultra was 75.5% sensitive and 100% specific relative to sputum MRS, similar to previous methods that used swabs stored in buffer. MTB Ultima was 71.6% sensitive and 96.9% specific relative to sputum MRS. When sample lysates that were false-negative or invalid by MTB Ultima were frozen, thawed, and re-tested, MTB Ultima sensitivity rose to 79.1%. Both tests were more sensitive with swabs from participants with higher sputum Xpert Ultra semi-quantitative results. Although additional development could improve diagnostic accuracy, these results further support tongue swabs as easy-to-collect samples for TB testing.

IMPORTANCE

Tongue dorsum swabbing is a promising alternative to sputum collection for tuberculosis (TB) testing. Our results lend further support for tongue swabs as exceptionally easy-to-collect samples for high-throughput TB testing.

Active Tuberculosis Screening via a Mobile Health App in Myanmar: Incremental Cost-Effectiveness Evaluation

BACKGROUND

A mobile app that calculates a tuberculosis (TB) risk score based on individual social and pathological characteristics has been shown to be a better predictor of the risk of contracting TB than conventionally used TB signs and symptoms (TBSS) in Myanmar, where the TB burden is high. Its cost-effectiveness, however, has not yet been assessed.

OBJECTIVE

This study aimed to determine the incremental costs of this mobile app and of chest x-rays (CXRs) in averting disability-adjusted life years (DALYs) among missed cases of active TB in the population being screened.

METHODS

Elements of incremental costs and effectiveness of 3 initial TB screening strategies were examined, including TBSS followed by CXR, the mobile app followed by CXR, and universal CXR. The incremental cost-effectiveness ratio (ICER; ie, the additional cost for each additional DALY averted) was compared to TBSS screening. Based on the latest 2020 gross domestic product (GDP) per capita of Myanmar (US $1477.50), the ICER was compared to willingness-to-pay (WTP) thresholds of 1, 2, and 3 times the GDP per capita. Probabilistic sensitivity analysis was conducted with a Monte Carlo simulation to compute the levels of probability that the ICER for each strategy was below each WTP threshold.

RESULTS

For each 100,000 population, the incremental cost compared to TBSS of active TB screening was US $345,942 for the mobile app and US $1,810,712 for universal CXR. The incremental effectiveness was 325 DALYs averted for the mobile app and 576 DALYs averted for universal CXR. For the mobile app, the estimated ICER was US $1064 (72% of GDP per capita) per 1 DALY averted. Furthermore, 100% of the simulated values were below an additional cost of 1 times the GDP per capita for 1 additional DALY averted. The universal CXR strategy has an estimated ICER of US $3143 (2.1 times the GDP per capita) per 1 DALY averted and an additional 77.2% DALYs averted compared to the app (ie, 576 - 325 / 325 DALYs); however, 0.5% of the simulated values were higher than an additional expenditure of 3 times the GDP per capita.

CONCLUSIONS

Based on the status of the economy in 2020, the mobile app strategy is affordable for Myanmar. The universal CXR strategy, although it could prevent an additional 77% of DALYs, is probably unaffordable. Compared to the TBSS strategy, the mobile app system based on social and pathological characteristics of TB has potential as a TB screening tool to identify missing TB cases and to reduce TB morbidity and mortality, thereby helping to achieve the global goal of "End TB" in resource-limited settings with a high TB burden.

Adherence and Toxicity during the Treatment of Latent Tuberculous Infection in a Referral Center in Spain

The screening and treatment of latent tuberculosis infection (LTBI) in countries with a low incidence of TB is a key strategy for the elimination of tuberculosis (TB). However, treatment can result in adverse events (AEs) and have poor adherence. This study aimed to describe treatment outcomes and AEs for LTBI patients at two departments in Vall d'Hebron University Hospital in Barcelona, Spain. A retrospective study was conducted on all persons treated for LTBI between January 2018 and December 2020. Variables collected included demographics, the reason for LTBI screening and treatment initiation, AEs related to treatment, and treatment outcome. Out of 261 persons who initiated LTBI treatment, 145 (55.6%) were men, with a median age of 42.1 years. The indications for LTBI screening were household contact of a TB case in 96 (36.8%) persons, immunosuppressive treatment in 84 (32.2%), and recently arrived migrants from a country with high TB incidence in 81 (31.0%). Sixty-three (24.1%) persons presented at least one AE during treatment, and seven (2.7%) required definitive discontinuation of treatment. In the multivariate analysis, AE development was more frequent in those who started LTBI treatment due to immunosuppression. Overall, 226 (86.6%) completed treatment successfully. We concluded that LTBI screening and treatment groups had different risks for adverse events and treatment outcomes. Persons receiving immunosuppressive treatment were at higher risk of developing AEs, and recently arrived immigrants from countries with a high incidence of TB had greater LTFU. A person-centered adherence and AE management plan is recommended.

Tuberculosis infection following immune checkpoint inhibitor treatment for advanced cancer: a case report and literature review

Objective

To investigate the clinical features of active tuberculosis (TB) infection due to immune checkpoint inhibitors (ICIs) treatment in patients with advanced cancer.

Methods

We report the diagnosis and treatment of a case of pulmonary malignancy (squamous cell carcinoma, cT4N3M0 IIIC), secondary to active TB infection following ICIs therapy. Moreover, we summarize and analyze other related cases collected from the China National Knowledge Infrastructure (CNKI), Wanfang Database, PubMed, the Web of Science, and EMBASE (up to October 2021).

Results

A total of 23 patients, including 20 males and 3 females who were aged 49-87 years with a median age of 65 years, were included in the study. Twenty-two patients were diagnosed by Mycobacterium tuberculosis culture or DNA polymerase chain reaction (PCR), while the remaining patient was diagnosed by tuberculin purified protein derivative and pleural biopsy. One case had an interferon-gamma release assay (IGRA) to rule out latent TB infection prior to the application of ICI. Fifteen patients received an anti-tuberculosis regimen. Among the 20 patients with a description of clinical regression, 13 improved and 7 died. Seven of the patients who improved were treated with ICI again and four of them did not experience a recurrence or worsening of TB. The case diagnosed in our hospital also improved after receiving anti-TB treatment after stopping ICI therapy, and continued chemotherapy on the basis of anti-TB treatment, and his condition is relatively stable at present.

Conclusion

Due to the lack of specificity of TB infection following ICIs therapy, patients should be followed for fever and respiratory symptoms for 6.3 months after drug administration. It is recommended that IGRA should be performed before ICIs therapy and the development of TB during immunotherapy in patients who are positive in IGRA should be closely monitored. The symptoms of TB in most patients can be improved with ICIs withdrawal and anti-TB treatment, but there is still a need to be alert to the potentially fatal risk of TB.

Disseminated tuberculosis in a lung transplant recipient presenting as tenosynovitis, subcutaneous nodules, and liver abscesses

Tuberculosis is of particular concern in lung transplant recipients. We present the case of a patient who received a double lung transplant from a deceased donor from Mexico and developed disseminated tuberculosis 60 days post-transplant manifested as tenosynovitis, liver abscesses, and subcutaneous nodules with no definitive lung allograft involvement. The recipient did not have evidence of tuberculosis on explanted lungs, had a negative interferon gamma release assay pre-transplant, and did not have risk factors for this infection. Mycobacterium tuberculosis should remain in the differential diagnosis of early post-transplant infections with atypical presentations, evidence of dissemination, or lack of improvement with appropriate antimicrobial coverage, even in the absence of typical lung findings.

Same-day antiretroviral therapy initiation for people living with HIV who have tuberculosis symptoms: a systematic review

OBJECTIVES

Tuberculosis symptoms are very common among people living with HIV (PLHIV) initiating antiretroviral therapy (ART), are not specific for tuberculosis disease and may result in delayed ART start. The risks and benefits of same-day ART initiation in PLHIV with tuberculosis symptoms are unknown.

METHODS

We systematically reviewed nine databases on 12 March 2020 to identify studies that investigated same-day ART initiation among PLHIV with tuberculosis symptoms and reported both their approach to TB screening and clinical outcomes. We extracted and summarized data about TB screening, numbers of people starting same-day ART and outcomes.

RESULTS

We included four studies. Two studies deferred ART for everyone with any tuberculosis symptoms (one or more of cough, fever, night sweats or weight loss) and substantial numbers of people had deferred ART start (28% and 39% did not start same-day ART). Two studies permitted some people with tuberculosis symptoms to start same-day ART, and fewer people deferred ART (2% and 16% did not start same-day). Two of the four studies were conducted sequentially; proven viral load suppression at 8 months was 31% when everyone with tuberculosis symptoms had ART deferred, and 44% when the algorithm was changed so that some people with tuberculosis symptoms could start same-day ART.

CONCLUSIONS

Although tuberculosis symptoms are very common in people starting ART, there is insufficient evidence about whether presence of tuberculosis symptoms should lead to ART start being deferred or not. Research to inform clear guidelines would help to maximise the benefits of same-day ART.

Establishing the cost of Xpert MTB/RIF mobile testing in high-burden peri-mining communities in South Africa

Background

Globally, tuberculosis remains a major cause of mortality, with an estimated 1.3 million deaths per annum. The Xpert MTB/RIF assay is used as the initial diagnostic test in the tuberculosis diagnostic algorithm. To extend the national tuberculosis testing programme in South Africa, mobile units fitted with the GeneXpert equipment were introduced to high-burden peri-mining communities.

Objective

This study sought to assess the cost of mobile testing compared to traditional laboratory-based testing in a peri-mining community setting.

Methods

Actual cost data for mobile and laboratory-based Xpert MTB/RIF testing from 2018 were analysed using a bottom-up ingredients-based approach to establish the annual equivalent cost and the cost per result. Historical cost data were obtained from supplier quotations and the local enterprise resource planning system. Costs were obtained in rand and reported in United States dollars (USD).

Results

The mobile units performed 4866 tests with an overall cost per result of $49.16. Staffing accounted for 30.7% of this cost, while reagents and laboratory equipment accounted for 20.7% and 20.8%. The cost per result of traditional laboratory-based testing was $15.44 US dollars (USD). The cost for identifying a tuberculosis-positive result using mobile testing was $439.58 USD per case, compared to $164.95 USD with laboratory-based testing.

Conclusion

Mobile testing is substantially more expensive than traditional laboratory services but offers benefits for rapid tuberculosis case detection and same-day antiretroviral therapy initiation. Mobile tuberculosis testing should however be reserved for high-burden communities with limited access to laboratory testing where immediate intervention can benefit patient outcomes.

A comparative analysis of tuberculosis in vitro screening in pemphigus patients selected for treatment with rituximab

Introduction

Patients qualified for the Polish government programme of treating severe pemphigus diseases with rituximab (RTX) available in 2018-2019 had to meet numerous criteria, including no active infectious disease.

Aim

The clinical usefulness of tuberculosis screening with the QuantiFERON-TB Gold Plus (QFT-Plus) in native pemphigus patients selected for RTX treatment was statistically evaluated.

Material and methods

Eighteen pemphigus patients were examined with QFT-Plus prior to the intended RTX therapy. Ninety hospital employees examined with QFT-Plus due to contact with a cleaning worker who was diagnosed with active pulmonary tuberculosis were the control group.

Results

Six of 18 pemphigus patients had a positive QFT-Plus test result, one indefinite result and one initially indefinite and then negative. In the control group, 26 of 90 employees had a positive test result and none had an indefinite result. Statistical analysis by Fisher's exact test showed no statistically significant difference in QFT-Plus positive results between the groups (p = 0.5577). Only in 1 patient with recurrent mucocutaneous pemphigus vulgaris previously treated with traditional immunosuppression, lung changes were detected by computed tomography. No employee had any changes in the chest radiograph.

Conclusions

Prior immunosuppression and autoimmunity might be the cause of indefinite test results, but they do not seem to increase positive results. In the native population, the QFT-Plus screening reveals a significant population exposure to M. tuberculosis infection independent of pemphigus autoimmunity, and such screening can be a starting point for identifying patients requiring anti-tuberculosis drug prophylaxis before combined RTX-glucocorticosteroid treatment.

Active tuberculosis risk associated with malignancies: an 18-year retrospective cohort study in Korea

Background

Active tuberculosis (TB) develops in approximately 10% of people with a latent tuberculosis infection (LTBI). TB guidelines recommend that LTBI screening and treatments target high-risk patients. Malignancies are not universally considered a high-risk factor for active TB. This study aimed to determine the degrees to which active TB risk was associated with various cancers in a Korean population.

Methods

This study involved patients aged ≥20 years who were diagnosed with cancer at Ulsan University Hospital (UUH) from January 2000 to December 2014 and individuals who visited UUH for health screening and were age- and sex-matched randomly with cases in a 1:2 ratio. Using retrospective cohort study, the development of bacteriologically confirmed TB (BCTB) within 3 years after enrollment was investigated. The relative risks of BCTB were estimated using incidence rate ratios (IRRs) and a Poisson regression analysis.

Results

During the study period, 380 of 34,783 cancer patients and 79 of 69,566 control subjects developed BCTB, yielding respective incidence rates of 535 and 37/100,000 person-years, respectively. In all cancer cases, the IRR of BCTB was 14.30, and especially high rates were associated with the following cancers: esophageal cancer (74.72), multiple myeloma (70.76), lung cancer (50.35), pancreatic cancer (46.04), leukemia (40.45), head and neck cancer (24.60), and lymphoma (22.67).

Conclusions

The incidence of active TB was higher in cancer patients than in control subjects. In particular, lung cancer, esophageal cancer, pancreatic cancer, hematologic malignancy and head and neck cancer were identified as high-risk factors for active TB, as indicated by IRRs of 20-75. These findings suggest that patients with high-risk cancers should be targeted for LTBI screening and treatment.

Detecting tuberculosis in pregnant and postpartum women in Eswatini

Background

Tuberculosis diagnosis in pregnancy is complex because tuberculosis symptoms are often masked by physiological symptoms of pregnancy. Untreated tuberculosis in pregnant and postpartum women may lead to maternal morbidity and low birth weight. Tuberculosis in HIV-positive pregnant women increases the risk of maternal and infant mortality.

Objective

This study aimed to determine tuberculosis prevalence stratified by HIV status and identify screening algorithms that maximise detection of active tuberculosis among pregnant and postpartum women in Eswatini.

Methods

Women were enrolled at antenatal and postnatal clinics in Eswatini for tuberculosis screening and diagnostic investigations from 01 April to 30 November 2015 in a cross-sectional study. Sputum samples were collected from all participants for tuberculosis diagnostic tests (smear microscopy, GeneXpert, MGIT culture). Blood and urine samples were collected from HIV-positive women for cluster-of-differentiation-4 cell count, interferon gamma release assay and tuberculosis lateral flow urine lipoarabinomannan tests.

Results

We enrolled 990 women; 52% were pregnant and 47% were HIV-positive. The prevalence of tuberculosis among HIV-positive pregnant women was 5% (95% confidence interval [CI]: 2-7) and among postpartum women it was 1% (95%CI: -1-3). Tuberculosis prevalence was 2% (95%CI: 0-3) in HIV-negative pregnant women and 1% (95%CI: -1-2) in HIV-negative postpartum women. The national tuberculosis symptom screening tool failed to identify women who tested tuberculosis-culture positive.

Conclusion

Routine tuberculosis symptom screening alone is insufficient to rule out tuberculosis in pregnant and postpartum women. Only sputum culture maximised the detection of tuberculosis, indicating a need to balance access and cost in developing countries.

Increasing isoniazid preventive therapy uptake in an HIV program in rural Papua New Guinea

Setting: Tuberculosis (TB) is the leading cause of death among people living with the human immunodeficiency virus (PLHIV) in Papua New Guinea. Despite a policy for isoniazid preventive therapy (IPT) among PLHIV, implementation has been slow. Objective: We prospectively evaluated a standardized guided screening process, including TB diagnostic support, to increase IPT initiation in adult PLHIV on antiretro-viral treatment. Design: The guided process included a paper-based IPT screening tool that prompted review of patient history and TB symptoms and sputum analysis by smear microscopy and Xpert^® MTB/RIF. Chest X-ray was performed at the provider's discretion. We quantified the yield of this guided process on IPT initiation and detection of TB and rifampicin resistance, and examined the contributions of each diagnostic modality. Results: Among 532 patients, TB was ruled out and IPT initiated in 450 (84%). TB was diagnosed and treatment was started in 82 (15%) patients. Xpert detected rifampicin resistance in one of 21 patients (5%, 95%CI 0.24-21.3) with a positive Xpert result. All TB cases were diagnosed by chest X-ray and/or Xpert. No cases were diagnosed by sputum smear alone. Conclusion: A standardized guided process, including TB diagnostic support, successfully enabled IPT initiation and identified a large burden of undetected TB.

Implementing intensified tuberculosis case-finding among street-connected youth and young adults in Kenya

BACKGROUND

Street-connected youth and young adults (SCY) suffer a myriad of health problems. In Kenya, SCY are at high risk for tuberculosis (TB) due to their congregate living situations. TB screening is not routinely implemented in SCY and there has been no published literature on the burden of TB in SCY in western Kenya.

PROGRAM DESCRIPTION

In 2011, the AMPATH TB Program, an experienced TB screening program, partnered with the Tumaini Center, a trusted street youth organization, to conduct intensified case finding (ICF) for pulmonary TB among SCY. Our program aimed to investigate the numbers of SCY who reported symptoms and those diagnosed with smear-positive pulmonary TB, and link SCY with TB to treatment.

RESULTS

Of 116 SCY who were screened, 114 (98%) had a positive questionnaire; 104 (90%) provided a spot sputum sample, 39 (34%) provided a morning sputum sample, and 111 (97%) reported cough of >2 weeks. One street youth tested smear-positive for TB and was treated through to cure.

CONCLUSIONS

Implementing TB ICF is feasible in low-resource settings through unique collaborations between health care programs and community-based organizations. In addition to identifying smear-positive TB, our program uncovered a high burden of respiratory symptoms among SCY in Eldoret, Kenya.

The effectiveness of screening with interferon-gamma release assays in a university health care setting with a diverse global population

OBJECTIVE

This analysis examined the effectiveness of utilizing interferon-gamma release assay (IGRA) technology in a TB (TB) screening program at a university.

PARTICIPANTS

Participants were 2299 students at a Montana university who had presented to the university health center for TB screening during 2012 and 2013.

METHODS

A retrospective study was conducted utilizing data from student health center medical records. Time and financial expenditures were determined, and the cost of the present screening process and 2 alternative scenarios was calculated.

RESULTS

The current process is the most costly and time-consuming scenario for TB testing. Testing exclusively with IGRAs is the least labor-intensive for staff and creates revenue, whereas a dual method, utilizing IGRAs for high-risk students and skin tests for others, provides a solution that better responds to the demographic of the population.

CONCLUSIONS

This assessment shows that IGRAs are a cost-effective tool for screening a global student population.

Validity of a self-reported history of a positive tuberculin skin test. A prospective study of drug users

OBJECTIVE

To define the prevalence of and factors associated with having a negative purified protein derivative (PPD) among persons who self-report a prior positive PPD and to define the safety of repeat testing in such persons.

DESIGN

Observational cohort study.

SETTING

Methadone maintenance program with onsite primary care.

PATIENTS/PARTICIPANTS

Current or former drug users enrolled in methadone maintenance treatment.

INTERVENTIONS

Structured interview, tuberculin skin testing regardless of self-reported PPD status, and anergy testing.

MEASUREMENTS AND MAIN RESULTS

Nearly one third (31%) of participants who self-reported a prior positive PPD had a negative measured PPD, despite receipt of a "booster" PPD. A single participant (0.5%) blistered in response to the PPD without lasting ill effect. Participants with PPD results discordant from their history were more likely to be HIV-seropositive and nonreactive to the anergy panel. The discordance rate among HIV-infected participants was 43%, and was largely attributable to immune dysfunction. Among HIV-seronegative participants, the discordance rate was 27%. Recent crack-cocaine use was independently associated with discordance in the absence of HIV infection.

CONCLUSIONS

We confirmed that planting a PPD in patients who self-report a positive PPD history confers minimal risk. Substantial rates of discordance exist between self-reported history of a positive PPD and measured PPD status. Further research is needed to define the optimal management of PPD-negative patients who self-report a prior positive PPD and who have not received prior treatment for latent tuberculosis.