Tools to implement the World Health Organization End TB Strategy: Addressing common challenges in high and low endemic countries

Prevalence of tuberculosis infection among contacts of drug-resistant tuberculosis patients: A systematic review and meta-analysis

INTRODUCTION

Contact investigations with drug-susceptible tuberculosis (DS-TB) patients have demonstrated a high prevalence of tuberculosis infection (TBI). However, the prevalence of TBI among individuals in close contact with drug-resistant tuberculosis (DR-TB) patients is poorly understood. This systematic review and meta-analysis aimed to determine the prevalence of TBI among household and non-household contacts of DR-TB patients.

METHOD AND ANALYSIS

We searched five databases (Medline, Embase, Scopus, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL)) from inception to 2 June 2023. All studies that reported the prevalence of TBI among DR-TB contacts were included in the study. A random-effects meta-analysis was conducted to estimate the pooled prevalence of TBI with a 95% confidence interval (CI). Sub-group analyses were conducted using study characteristics as covariates.

RESULTS

Thirty studies involving 7659 study participants from 19 countries were included. The pooled prevalence of TBI among DR-TB contacts was 36.52% (95% CI: 30.27-42.77). The sub-group analysis showed considerable heterogeneity in the estimates, with the highest prevalence reported in Southeast Asia (80.74%; 95% CI: 74.09-87.39), household contacts (38.60%; 95% CI: 30.07-47.14), lower-middle-income countries (LMICs) (54.72; 95% CI: 35.90, 73.55), children (43.27%; 95% CI: 25.50, 61.04), and studies conducted between 2004 and 2012 (45.10; 95% CI: 32.44, 57.76).

CONCLUSION

The prevalence of TBI among DR-TB contacts was high, with substantial regional variations. Further research is needed to determine the drug susceptibility status of TBI in DR-TB contacts.

PROTOCOL REGISTRATION

The protocol is registered in PROSPERO (CRD42023390339).

Synthesis of indole-functionalized isoniazid conjugates with potent antimycobacterial and antioxidant efficacy

Aim: Developing potent medicinal alternates for tuberculosis (TB) is highly desirable due to the advent of drug-resistant lethal TB strains. Methods & results: Novel indole-isoniazid integrates have been synthesized with promising antimycobacterial action against the H37Rv strain, and the nitro analogs 4e and 4j show the highest efficacy with a minimum inhibitory concentration of 1.25 μg/ml. The molecular docking studies against InhA support the experimental findings. Indole conjugates display remarkable radical quenching efficiency, and compounds 4e and 4j demonstrate maximum IC50 values of 50.19 and 52.45 μg/ml, respectively. Pharmacokinetic analysis anticipated appreciable druggability for the title compounds. Conclusion: The notable bioaction of the indole-isoniazid templates projects them as potential lead in developing anti-TB medications with synergetic antioxidant action.

The occurrence rate of Haarlem and Beijing genotypes among Middle Eastern isolates of multi drug resistant Mycobacterium tuberculosis: A systematic review and meta-analysis

Antibiotic resistance is a serious problem that poses a major challenge to tuberculosis control worldwide. Many developing countries still struggle with this infection in term of various aspects as it remains a major health concern. A number of developing countries are located in the Middle East, one of the world's most important regions. The control of this infection remains largely suboptimal despite intensive research in the field, and the mechanisms that lead to its progression have not yet been fully understood. Therefore, TB control must be amended through the identification of new strategies. For this reason, monitoring genetic characterizations of TB strains by molecular typing methods in different geographical regions can be important to setting local programs and global strategies to control TB infection. It is important to know the genotype of Mycobacterium tuberculosis strains to evaluate the occurrence of outbreaks and the transmission of this disease. Beijing and Haarlem genotypes are the most prevalent and, in these families, there is greater association with drug resistance, resulting in more severe forms of TB and higher levels of treatment failure than in other families. The current study is planned to systematically conduct a review using a meta-analysis to show the prevalence of Beijing and Haarlem genotypes in the Middle Eastern MDR-TB cases. M. tuberculosis strains pose particular epidemiological and clinical concerns as they can endanger tuberculosis control programs.

Delivery of Mycobacterium tuberculosis epitopes by Bordetella pertussis adenylate cyclase toxoid expands HLA-E-restricted cytotoxic CD8+ T cells

Introduction

Tuberculosis (TB) remains the first cause of death from infection caused by a bacterial pathogen. Chemotherapy does not eradicate Mycobacterium tuberculosis (Mtb) from human lungs, and the pathogen causes a latent tuberculosis infection that cannot be prevented by the currently available Bacille Calmette Guerin (BCG) vaccine, which is ineffective in the prevention of pulmonary TB in adults. HLA-E-restricted CD8+ T lymphocytes are essential players in protective immune responses against Mtb. Hence, expanding this population in vivo or ex vivo may be crucial for vaccination or immunotherapy against TB.

Methods

The enzymatically inactive Bordetella pertussis adenylate cyclase (CyaA) toxoid is an effective tool for delivering peptide epitopes into the cytosol of antigen-presenting cells (APC) for presentation and stimulation of specific CD8+ T-cell responses. In this study, we have investigated the capacity of the CyaA toxoid to deliver Mtb epitopes known to bind HLA-E for the expansion of human CD8+ T cells in vitro.

Results

Our results show that the CyaA-toxoid containing five HLA-E-restricted Mtb epitopes causes significant expansion of HLA-E-restricted antigen-specific CD8+ T cells, which produce IFN-γ and exert significant cytotoxic activity towards peptide-pulsed macrophages.

Discussion

HLA-E represents a promising platform for the development of new vaccines; our study indicates that the CyaA construct represents a suitable delivery system of the HLA-E-binding Mtb epitopes for ex vivo and in vitro expansion of HLA-E-restricted CD8+ T cells inducing a predominant Tc1 cytokine profile with a significant increase of IFN-γ production, for prophylactic and immunotherapeutic applications against Mtb.

Implications for TB control among migrants in large cities in China: A prospective population-based genomic epidemiology study in Shenzhen

Internal migrants are a challenge for TB control in large Chinese cities and understanding this epidemiology is crucial for designing effective control and prevention strategies. We conducted a prospective genomic epidemiological study of culture-positive TB patients diagnosed between June 1, 2018 and May 31, 2021 in the Longhua District of Shenzhen. Treatment status was obtained from local and national TB registries and all isolates were sequenced. Genomic clusters were defined as strains differing by ≤12 SNPs. Risk factors for clustering were identified with multivariable analysis and then Bayesian models and TransPhylo were used to infer the timing of transmission within clusters. Of the 2277 culture-positive patients, 70.1% (1596/2277) were migrants: 72.1% (1043/1446) of the migrants patients developed TB within two years of arriving in Longhua; 38.8% within 6 months of arriving; and 12.3% (104/843) had TB symptoms when they arrived. Only 15.4% of Longhua strains were in genomic clusters. More than one third (33.6%) of patients were not treated in Shenzhen but were involved in nearly one third of the recent transmission events. Clustering was associated with migrants not treated in Shenzhen, males, and teachers/trainers. TB in Longhua is prinicipally due to reactivation of infections in migrants, but a proportion may have had clinical or incipient TB upon arrival in the district. Patients diagnosed but not treated in Longhua were involved in recent local TB transmission. Controlling TB in Shenzhen will require strategies to comprehensively diagnose and treat active TB in the internal migrant population.

Mycobacterium tuberculosis epidemiology in Oman: whole-genome sequencing uncovers transmission pathways

Tuberculosis (TB) originating from expatriates that hail from high TB-burden countries is hypothesized to play a role in continued TB transmission in Oman. Here, we used whole-genome sequencing (WGS) to assess national TB transmission dynamics. The annual incidence per 100,000 population per year was calculated for nationals and expatriates. A convenience sample of Mycobacterium tuberculosis (MTB) isolates from 2018 to 2019 was sequenced and analyzed with publicly available TB sequences from Bangladesh, Tanzania, the Philippines, India, and Pakistan. Relatedness was assessed by generating core-genome single nucleotide polymorphism (SNP) distances. The incidence of TB was five cases per 100,000 persons in 2018 and seven cases per 100,000 persons in 2020 (R2 = 0.34, P = 0.60). Incidence among nationals was 3.9 per 100,000 persons in 2018 and 3.5 per 100,000 persons in 2020 (R2 = 0.20, P = 0.70), and incidence among expatriates was 7.2 per 100,000 persons in 2018 and 12.7 per 100,000 persons in 2020 (R2 = 0.74, P = 0.34). Sixty-eight local MTB isolates were sequenced and analyzed with 393 global isolates. Isolates belonged to nine distinct spoligotypes. Two isolates, originating from an expatriate and an Omani national, were grouped into a WGS-based cluster (SNP distance < 12), which was corroborated by an epidemiological investigation. Relatedness of local and global isolates (SNP distance < 100) was also seen. The relatedness between MTB strains in Oman and those in expatriate countries of origin can aid inform TB control policy. Our results provide evidence that WGS can complement epidemiological analysis to achieve the End TB strategy goal in Oman. IMPORTANCE Tuberculosis (TB) incidence in Oman remains above national program control targets. TB transmission originating from expatriates from high TB-burden countries has been hypothesized to play a role. We used whole-genome sequencing (WGS) to assess TB transmission dynamics between expatriates and Omani nationals to inform TB control efforts. Available Mycobacterium tuberculosis isolates from 2018 to 2019 underwent WGS and analysis with publicly available TB sequences from Bangladesh, the Philippines, India, and Pakistan to assess for genetic relatedness. Our analysis revealed evidence of previously unrecognized transmission between an expatriate and an Omani national, which was corroborated by epidemiological investigation. Analysis of local and global isolates revealed evidence of distant relatedness between local and global isolates. Our results provide evidence that WGS can complement classic public health surveillance to inform targeted interventions to achieve the End TB strategy goal in Oman.

Cost analysis of GenoType® MTBDRplus and GenoType® MTBDRsl at the State Laboratory of São Paulo, Brazil

BACKGROUND

We aimed to evaluate the costs of GenoType® MTBDRplus and MTBDRsl incurred during the diagnosis of first- and second-line drug-resistant tuberculosis (TB) in São Paulo, Brazil.

METHODS

Mean and activity-based costs of GenoType® were calculated in a referral laboratory for TB in Brazil.

RESULTS

The mean cost value and activity-based cost of GenoType® MTBDRplus were USD 19.78 and USD 35.80 and those of MTBDRsl were USD 54.25 and USD 41.85, respectively.

CONCLUSIONS

The cost of GenoType® MTBDRplus was reduced owing to the high number of examinations performed and work optimization.

A cost-effectiveness evaluation of latent tuberculosis infection screening of a migrant population in Malaysia

To estimate the costs and benefits of screening for latent tuberculosis infection (LTBI) in a migrant population in Malaysia. An economic model was developed from a Malaysian healthcare perspective to compare QuantiFERON-TB Gold Plus (QuantiFERON) with the tuberculin skin test (TST). A decision tree was used to capture outcomes relating to LTBI screening followed by a Markov model that simulated the lifetime costs and benefits of the patient cohort. The Markov model did not capture the impact of secondary infections. The model included an R shiny interactive interface to allow adaptation to other scenarios and settings. QuantiFERON is both more effective and less costly than TST (dominant). Compared with QuantiFERON, the lifetime risk of developing active TB increases by approximately 40% for TST due to missed LTBI cases during screening (i.e. a higher number of false negative cases for TST). For a migrant population in Malaysia, QuantiFERON is cost-effective when compared with TST. Further research should consider targeted LTBI screening for migrants in Malaysia based on common risk factors.

Clinician perspectives of drug-resistant tuberculosis care services in the Philippines

BACKGROUND/OBJECTIVES

In the Philippines, treatment success rates for drug-resistant tuberculosis (DR-TB) remains low and little is known about the quality of DR-TB services. This study aimed to explore clinician's perspectives of DR-TB care services.

METHODS

We conducted semi-structured in-depth interviews from January-March 2018 with 11 providers selected purposively to explore the barriers associated with DR-TB care service delivery, best practices, and recommendations for enhancing patient care. Emerging themes were organized according to the socio-ecological framework.

RESULTS

Five major themes were identified: (1) nurses do not feel empowered; (2) particular patients are left behind and more vulnerable than others; (3) infection control practices, fear, and limited capacity in rural health centers; (4) financial insecurity due to program reimbursement mechanisms; and (5) local government support is limited and requires more involvement in support of DR-TB elimination activities. Best practices focused on tailored approaches that eliminated structural, economic, and motivational barriers for patients. Participants recommended financial support from local government units, nutritional assistance for patients, and refresher training for healthcare workers.

CONCLUSION

The findings provide additional understanding regarding the barriers that limit successful DR-TB care delivery and provide critical information to improve clinical practice and develop public health interventions for frontline staff including nurses in the Philippines. These strategies could ultimately reduce disparities associated with access to care and treatment adherence, if implemented.

Assessing Oman's knowledge, attitude and practice regarding tuberculosis: a cross-sectional study that calls for action

BACKGROUND

Tuberculosis (TB) remains a major public health issue. Elimination mandates collaboration between decision makers, practitioners and the community. Few studies address the knowledge, attitude and practice (KAP) from countries with low incidence.

AIM

Assess KAP regarding TB in Oman.

METHOD

A cross-sectional survey based on validated questionnaire conducted via phone on randomly selected participants.

RESULTS

A total of 1048 participants completed the questionnaire. Males accounted for 63% (n=664) of respondents, Omanis 76% (n=796) and 18-39-year-olds 50% (n=527). The overall knowledge was fair (53%), overall attitude scored good and fair (46%) equally and a good score (78%) for overall practice. While female gender associated with higher knowledge (53.9%, n=201), males showed higher attitude and practice, (48.5%, n=322) and (80.3%, n=533) respectively. Omani nationality correlated with higher knowledge (49.1%, n= 391) and attitude (46.9%, n=373) whereas non-Omani nationality correlated with higher practice (85.3%, n=214). Literacy was associated with higher knowledge (73.3%, n=11) and attitude (60%, n=9).

CONCLUSION

Despite efforts by the Ministry of Health, more must be done to raise TB knowledge to encourage preferable attitudes and practice. Interventions to improve KAP are required to speed up disease reduction rate. Utilization of different resources, especially digital platforms, for knowledge dissemination should consider community diversity, including the presence of expatriates.

Respiratory vaccination

Vaccinations are among the most cost-effective preventive health strategies to reduce healthcare costs and prevent morbidities. Every year, many adults and elderly encounter hospitalization because of infectious respiratory diseases. Among these, viral and bacterial pneumonia, tuberculosis, diphtheria and pertussis infections are some of the diseases that can be prevented and managed with fewer complications, with adequate preventive immunization. This review tries to outline the vaccines available for the prevention of these respiratory ailments along with their schedule and dosages.

BCG and SARS-CoV-2-What Have We Learned?

Despite controversy over the protective effect of the BCG (Bacille Calmette-Guérin) vaccine in preventing pulmonary tuberculosis (TB) in adults, it has been used worldwide since 1921. Although the first reports in the 1930s had noted a remarkable decrease in child mortality after BCG immunization, this could not be explained solely by a decrease in mortality from TB. These observations gave rise to the suggestion of nonspecific beneficial effects of BCG vaccination, beyond the desired protection against M. tuberculosis. The existence of an innate immunity-training mechanism based on epigenetic changes was demonstrated several years ago. The emergence of the pandemic caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2) in 2019 revived the debate about whether the BCG vaccine can affect the immune response against the virus or other unrelated pathogens. Due to the mortality of the coronavirus disease (COVID-19), it is important to verify each factor that may have a potential protective value against the severe course of COVID-19, complications, and death. This paper reviews the results of numerous retrospective studies and prospective trials which shed light on the potential of a century-old vaccine to mitigate the pandemic impact of the new virus. It should be noted, however, that although there are numerous studies intending to verify the hypothesis that the BCG vaccine may have a beneficial effect on COVID-19, there is no definitive evidence on the efficacy of the BCG vaccine against SARS-CoV-2.

Drug resistant Mycobacterium tuberculosis in Oman: resistance-conferring mutations and lineage diversity

Background

The Sultanate of Oman is country a low TB-incidence, with less than seven cases per 10⁵ population detected in 2020. Recent years have witnessed a persistence in TB cases, with sustained incidence rate among expatriates and limited reduction among Omanis. This pattern suggests transmission from the migrant population. The present study examined the genetic profile and drug resistance-conferring mutations in Mycobacterium tuberculosis collected from Omanis and expatriates to recognise possible causes of disease transmission.

Methods

We examined M. tuberculosis cultured positive samples, collected from Omanis (n = 1,344) and expatriates (n = 1,203) between 2009 and 2018. These isolates had a known in vitro susceptibility profile to first line anti-TB, Streptomycin (SM), Isoniazid (INH), Rifampicin (RIF), Ethambutol (EMB) and Pyrazinamide (PZA). The diversity of the isolates was assessed by spacer oligo-typing (spoligotyping). Drug resistance-conferring mutations resulted from full-length sequence of nine genes (katG, inhA, ahpc, rpoB, rpsL, rrs, embB, embC, pncA) and their phenotypic relationship were analysed.

Results

In total, 341/2192 (13.4%), M. tuberculosis strains showed resistance to any drug, comprising mono-resistance (MR) (242, 71%), poly-resistance (PR) (40, 11.7%) and multi-drug resistance (MDR) (59, 17.3%). The overall rate of resistance among Omanis and expatriates was similar; however, MDR and PZA^R were significantly higher among Omanis, while INH^R was greater among expatriates. Mutations rpsL K43R and rpoB S450L were linked to Streptomycin (SM^R) and Rifampicin resistance (RIF^R) respectively. Whereas, katG S315T and inhA -C15T/G-17T were associated with Isoniazid resistance (INH^R). The resistance patterns (mono-resistant, poly-resistant and MDR) and drug resistance-conferring mutations were found in different spoligo-lineages. rpsL K43R, katG S315T and rpoB S450L mutations were significantly higher in Beijing strains.

Conclusions

Diverse drug resistant M. tuberculosis strains exist in Oman, with drug resistance-conferring mutations widespread in multiple spoligo-lineages, indicative of a large resistance reservoir. Beijing's M. tuberculosis lineage was associated with MDR, and multiple drug resistance-conferring mutations, favouring the hypothesis of migration as a possible source of resistant lineages in Oman.

Dynamics of Mycobacterium tuberculosis Lineages in Oman, 2009 to 2018

Study aim. Effective Tuberculosis (TB) control measures in Oman have reduced the annual incidence of tuberculosis cases by 92% between 1981 and 2016. However, the current incidence remains above the program control target of <1 TB case per 100,000 population. This has been partly attributed to a high influx of migrants from countries with high TB burdens. The present study aimed to elucidate Mycobacterium tuberculosis infection dynamics among nationals and foreigners over a period of 10 years. Methods. The study examined TB cases reported between 2009 and 2018 and examined the spatial heterogeneity of TB cases and the distribution of M. tuberculosis genotypes defined by spoligotypes and MIRU-VNTR among Omanis and foreigners. Results. A total of 484 spoligoprofiles were detected among the examined isolates (n = 1295). These include 943 (72.8%) clustered and 352 (27.2%) unique isolates. Diverse M. tuberculosis lineages exist in all provinces in Oman, with most lineages shared between Omanis and foreigners. The most frequent spoligotypes were found to belong to EAI (318, 30.9%), CAS (310, 30.1%), T (154, 14.9%), and Beijing (88, 8.5%) lineages. However, the frequencies of these lineages differed between Omanis and foreigners. Of the clustered strains, 192 MTB isolates were further analysed via MIRU-VNTR. Each isolate exhibited a unique MIRU-VNTR profile, indicative of absence of ongoing transmission. Conclusions. TB incidence exhibits spatial heterogeneity across Oman, with high levels of diversity of M. tuberculosis lineages among Omanis and foreigners and sub-lineages shared between the two groups. However, MIRU-VNTR analysis ruled out ongoing transmission.

Importance of Tuberculosis Screening of Resident Visa Applicants in Low TB Incidence Settings: Experience from Oman

Introduction

For Oman, a country targeting tuberculosis (TB) elimination, TB among expatriates is a major challenge. Thus, screening for active TB using chest X-ray was made mandatory for expatriates’ residency renewals.

Objective

To estimate the incidence of bacteriologically confirmed TB and assess impact of chest X-ray based TB screening among expatriates in Muscat Governorate.

Methods

Applicants for residency and renewals were mandated for chest X-ray-based TB screening in 2018. We collected data of screened subjects with radiological suspicion of TB who were subjected to further bacteriological evaluation.

Results

Of 501,290 applicants screened during the study period, 436 (0.09%) had X-ray findings suggestive of TB. Among the 436, TB was confirmed in 53 (12.2%; 95% CI 9.2–15.6), giving an overall prevalence of 10.6 (95% CI 8–13.9) per 100,000 applicants (number needed to be screened 9458). Among renewals, the point prevalence of TB was 10.5 per 100,000 expatriates screened (95% CI 6.9–14.04 per 100,000), with a mean follow-up period of 11.8 years.

Conclusion

Our findings are consistent with the recommendation for utilization of chest X-ray as a preferred tool for active case finding in the setting of expatriate screening. Our findings are also suggestive of the need for latent TB screening and ruling out TB prior to latent TB treatment.

Tuberculosis and isoniazid prophylaxis among adult HIV positive patients on ART in Northwest Ethiopia

Background

Although antiretroviral therapy (ART) can avert tuberculosis (TB) incidence among human immunodeficiency virus (HIV) infected patients, the concomitant use of ART with isoniazid (INH) has a paramount effect. Despite this evidence, there is a paucity of data regarding TB incidence among HIV patients on ART with and without isoniazid prophylaxis and its predictors. Thus, this study sought to assess the incidence and predictors of TB among adult HIV positive patients on ART.

Methods

This was a hospital based retrospective study including 368 adult HIV positive patients on ART in Gondar comprehensive specialized hospital between January 1, 2016, and April 30, 2019. Data was extracted from clinical laboratory and HIV care ART follow up clinic. The bi-variable and multivariable regression models were used to ascertain predictors of incident TB. Data was analyzed using SPSS version 20 software.

Results

A total of 335 adult HIV positive patients were included in the analysis, of whom, 56 (16.7%) were developed incident TB. Being ambulatory and bedridden (AOR: 2.2, 95% CI: 1.1, 4.6), advanced WHO clinical HIV disease stage (III and IV) (AOR: 3.2, 95% CI: 1.6, 6.1), not taking INH (AOR: 2.8, 95% CI: 1.3, 5.9), and baseline CD4+ T cell count ≤ 200 cell/mm3 (AOR: 3.6, 95% CI: 1.8, 7.2) were found to be the predictors of tuberculosis incidence.

Conclusion

The study indicated a high TB incidence among HIV positive patients in Gondar. Therefore, scaling up the isoniazid preventive therapy program and its strict compliance is necessary to avert HIV fueled tuberculosis in HIV endemic areas.

Platelets accumulate in lung lesions of tuberculosis patients and inhibit T-cell responses and Mycobacterium tuberculosis replication in macrophages

Platelets regulate human inflammatory responses that lead to disease. However, the role of platelets in tuberculosis (TB) pathogenesis is still unclear. Here, we show that patients with active TB have a high number of platelets in peripheral blood and a low number of lymphocytes leading to a high platelets to lymphocytes ratio (PL ratio). Moreover, the serum concentration of different mediators promoting platelet differentiation or associated with platelet activation is increased in active TB.

Immunohistochemistry analysis shows that platelets localise around the lung granuloma lesions in close contact with T lymphocytes and macrophages. Transcriptomic analysis of caseous tissue of human pulmonary TB granulomas, followed by Gene Ontology analysis, shows that 53 platelet activation‐associated genes are highly expressed compared to the normal lung tissue.

In vitro activated platelets (or their supernatants) inhibit BCG‐induced T‐ lymphocyte proliferation and IFN‐γ production. Likewise, platelets inhibit the growth of intracellular macrophages of Mycobacterium (M.) tuberculosis. Soluble factors released by activated platelets mediate both immunological and M. tuberculosis replication activities. Furthermore, proteomic and neutralisation studies (by mAbs) identify TGF‐β and PF4 as the factors responsible for inhibiting T‐cell response and enhancing the mycobactericidal activity of macrophages, respectively. Altogether these results highlight the importance of platelets in TB pathogenesis.

Lack of latent tuberculosis (TB) screening and delay in anti-retroviral therapy initiation in HIV-TB co-infection: an 11-year study in an intermediate TB-burden country

OBJECTIVES

To examine the prevalence and characteristics of HIV-tuberculosis (TB) co-infected patients in Singapore, an intermediate TB-burden country.

METHODS

Retrospective data across 11 years was obtained from the National University Hospital (NUH), a quaternary hospital and the National Centre for Infectious Diseases (NCID), the national HIV center.

RESULTS

From December 2005 to December 2016, 4015 HIV-infected patients were managed at NUH and NCID, of whom, respectively, 48 and 272 were diagnosed with active TB disease. Only 2 patients (0.6%) were screened for latent TB infection on HIV diagnosis. Mean CD4 count at TB diagnosis was 125.0 ± 153.9 cells/mm³. More patients with HIV diagnosed ≥6 weeks before TB (41%) were associated with CD4 counts >200 cells/mm³ than patients with TB diagnosed ≥6 weeks before HIV (2%). Of 124 (38.6%) HIV-TB patients with CD4 count ≤50 cells/mm³, only 18 (14.2%) started anti-retroviral therapy (ART) in <2 weeks. Of patients with pulmonary TB, 33.5% had normal chest x-ray.

CONCLUSIONS

Latent TB infection screening in HIV-infected patients is low, and ART initiation is delayed in HIV-TB patients with CD4 ≤50 cells/mm³. Pulmonary TB patients with HIV can be infectious despite normal chest x-ray. Clinical practices can be further improved to benefit HIV-TB patients.

New management approaches to tuberculosis in people living with HIV

PURPOSE OF REVIEW

People living with HIV (PLWH) are commonly coinfected with Mycobacterium tuberculosis, particularly in high-transmission resource-limited regions. Despite expanded access to antiretroviral therapy and tuberculosis (TB) treatment, TB remains the leading cause of death among PLWH. This review discusses recent advances in the management of TB in PLWH and examines emerging therapeutic approaches to improve outcomes of HIV-associated TB.

RECENT FINDINGS

Three recent key developments have transformed the management of HIV-associated TB. First, the scaling-up of rapid point-of-care urine-based tests for screening and diagnosis of TB in PLWH has facilitated early case detection and treatment. Second, increasing the availability of potent new and repurposed drugs to treat drug-resistant TB has generated optimism about the treatment and outcome of multidrug-resistant and extensively drug-resistant TB. Third, expanded access to the integrase inhibitor dolutegravir to treat HIV in resource-limited regions has simplified the management of TB/HIV coinfected patients and minimized serious adverse events.

SUMMARY

While it is unequivocal that substantial progress has been made in early detection and treatment of HIV-associated TB, significant therapeutic challenges persist. To optimize the management and outcomes of TB in HIV, therapeutic approaches that target the pathogen as well as enhance the host response should be explored.

TB contact tracing for young children: an Australian cascade of care review

OBJECTIVE

To evaluate care cascades for programmatic active case finding and latent TB infection (LTBI) management in young child TB contacts (aged <5 years) in Victoria, Australia.

DESIGN

This was a retrospective review of public health surveillance data to identify contacts of all pulmonary TB cases notified from 2016 to 2019.

RESULTS

Contact tracing identified 574 young child contacts of 251 pulmonary TB cases. Active TB was found in 28 (4.9%) contacts, none of whom had previously received bacille Calmette-Guérin vaccination, and 529 were tested for TB infection using the tuberculin skin test (TST). The overall TST positivity was 15.3% (95% CI 0.1-0.2). Among the 574 children, 150 (26.1%) were close contacts of sputum smear-positive cases and 25 (16.7%) of these were not referred to TB clinics. Of the 125 referred, 81 were considered to have LTBI, 79 agreed to commence TB preventive treatment (TPT) and 71 (89.9%) completed TPT. Following completion of TPT, no child was subsequently diagnosed with active TB.

CONCLUSION

There was a high yield from active case finding and uptake of TPT. Notable losses in the cascade of care occurred around referral to tertiary clinics, but high treatment completion rates and good outcomes were found in those prescribed treatment.

Detection of COVID-19 Using Deep Learning Algorithms on Chest Radiographs

PURPOSE

To evaluate the performance of a deep learning (DL) algorithm for the detection of COVID-19 on chest radiographs (CXR).

MATERIALS AND METHODS

In this retrospective study, a DL model was trained on 112,120 CXR images with 14 labeled classifiers (ChestX-ray14) and fine-tuned using initial CXR on hospital admission of 509 patients, who had undergone COVID-19 reverse transcriptase-polymerase chain reaction (RT-PCR). The test set consisted of a CXR on presentation of 248 individuals suspected of COVID-19 pneumonia between February 16 and March 3, 2020 from 4 centers (72 RT-PCR positives and 176 RT-PCR negatives). The CXR were independently reviewed by 3 radiologists and using the DL algorithm. Diagnostic performance was compared with radiologists' performance and was assessed by area under the receiver operating characteristics (AUC).

RESULTS

The median age of the subjects in the test set was 61 (interquartile range: 39 to 79) years (51% male). The DL algorithm achieved an AUC of 0.81, sensitivity of 0.85, and specificity of 0.72 in detecting COVID-19 using RT-PCR as the reference standard. On subgroup analyses, the model achieved an AUC of 0.79, sensitivity of 0.80, and specificity of 0.74 in detecting COVID-19 in patients presented with fever or respiratory systems and an AUC of 0.87, sensitivity of 0.85, and specificity of 0.81 in distinguishing COVID-19 from other forms of pneumonia. The algorithm significantly outperforms human readers (P<0.001 using DeLong test) with higher sensitivity (P=0.01 using McNemar test).

CONCLUSIONS

A DL algorithm (COV19NET) for the detection of COVID-19 on chest radiographs can potentially be an effective tool in triaging patients, particularly in resource-stretched health-care systems.

The Spectrum of Bacille Calmette-Guérin Diseases in Children-A Decade of Data from Neonatal Vaccination Settings

In this paper, we present a multicentre record-based descriptive study used to estimate the incidence and characterize the spectrum of confirmed bacille Calmette–Guérin (BCG) vaccine-related disease among children in Oman. This study included all children (age ≤ 14 years) who had culture and/or polymerase chain reaction (PCR)-confirmed BCG disease from January 2006 to December 2018, as identified from Central Public Health Laboratory data and International Classification of Diseases coding of an electronic patient information system. In total, 88 children confirmed to have BCG disease were included in the study, making an average incidence of 9.2 cases per 100,000 vaccinated neonates. The males comprised 65.9%, Omanis 93.2%, and the median age of presentation was 4 months in children with BCG disease. The most common type of disease was BCG abscesses (72.4%). Children with immunodeficiency and those presenting within 6 months were found to have a more severe and disseminated disease. In total, 28 children had immunodeficiency. The age of presentation and type of BCG disease was significantly associated with immunodeficiency status. The majority of cases required therapy (both medical and surgical) and recovered well. The incidence of laboratory-confirmed BCG vaccine-related disease was low in Oman supporting continuing the use of the BCG vaccination practice at birth.

BCG vaccine: a hope to control COVID-19 pandemic amid crisis

COVID-19 caused by the virus SARS-CoV-2 has gripped essentially all countries in the world, and has infected millions and killed hundreds of thousands of people. Several innovative approaches are in development to restrain the spread of SARS-CoV-2. In particular, BCG, a vaccine against tuberculosis (TB), is being considered as an alternative therapeutic modality. BCG vaccine is known to induce both humoral and adaptive immunities, thereby activating both nonspecific and cross-reactive immune responses in the host, which combined could effectively resist other pathogens including SARS-CoV-2. Notably, some studies have revealed that SARS-CoV-2 infectivity, case positivity, and mortality rate have been higher in countries that have not adopted BCG vaccination than in countries that have done so. This review presents an overview of the concepts underlying BCG vaccination and its nonspecific immuological effects and protection, resulting in 'trained immunity' and potential utility for resisting COVID-19.