ABSTRACT
BACKGROUND: Tuberculosis (TB) infectiousness decreases significantly with only a few days of treatment, but delayed diagnosis often leads to late treatment initiation. We conducted a sequential explanatory mixed methods study to understand the barriers and facilitators to prompt diagnosis among people with TB. METHODS: We enrolled 100 adults who started TB treatment in the Carabayllo district of Lima, Peru, between November 2020 and February 2022 and administered a survey about their symptoms and healthcare encounters. We calculated total diagnostic delay as time from symptom onset to diagnosis. We conducted semi-structured interviews of 26 participants who had a range of delays investigating their experience navigating the health system. Interview transcripts were inductively coded for concepts related to diagnostic barriers and facilitators. RESULTS: Overall, 38% of participants sought care first from public facilities and 42% from the private sector. Only 14% reported being diagnosed with TB on their first visit, and participants visited a median of 3 (interquartile range [IQR] health facilities before diagnosis. The median total diagnostic delay was 9 weeks (interquartile range [IQR] 4-22), with a median of 4 weeks (IQR 0-9) before contact with the health system and of 3 weeks (IQR 0-9) after. Barriers to prompt diagnosis included participants attributing their symptoms to an alternative cause or having misconceptions about TB, and leading them to postpone seeking care. Once connected to care, variations in clinical management, health facility resource limitations, and lack of formal referral processes contributed to the need for multiple healthcare visits before obtaining a diagnosis. Facilitators to prompt diagnosis included knowing someone with TB, supportive friends and family, referral documents, and seeing a pulmonologist. CONCLUSIONS: Misinformation about TB among people with TB and providers, poor accessibility of health services, and the need for multiple encounters to obtain diagnostic tests were major factors leading to delays. Extending the hours of operation of public health facilities, improving community awareness and provider training, and creating a formal referral process between the public and private sectors should be priorities in the efforts to combat TB.
Subject(s)
Delayed Diagnosis , Tuberculosis , Humans , Peru , Adult , Male , Female , Delayed Diagnosis/statistics & numerical data , Tuberculosis/diagnosis , Middle Aged , Health Services Accessibility , Young Adult , Patient Acceptance of Health Care/statistics & numerical data , Surveys and QuestionnairesABSTRACT
Mycobacterium tuberculosis is an extremely successful pathogen, and its success is widely attributed to its ability to manipulate the intracellular environment of macrophages. A central phenomenon of tuberculosis pathology enabling immune evasion is the capacity of virulent M. tuberculosis (H37Rv) to induce macrophage necrosis, which facilitates the escape of the mycobacteria from the macrophage and spread of infection. In contrast, avirulent M. tuberculosis (H37Ra) induces macrophage apoptosis, which permits Ag presentation and activation of adaptive immunity. Previously, we found that H37Rv induces plasma membrane microdisruptions, leading to necrosis in the absence of plasma membrane repair. In contrast, H37Ra permits plasma membrane repair, which changes the host cell death modality to apoptosis, suggesting that membrane repair is critical for sequestering the pathogen in apoptotic vesicles. However, mechanisms of plasma membrane repair induced in response to M. tuberculosis infection remain unknown. Plasma membrane repair is known to induce a Ca2+-mediated signaling, which recruits lysosomes to the area of damaged plasma membrane sites for its resealing. In this study, we found that the small GTPase Arl8b is required for plasma membrane repair by controlling the exocytosis of lysosomes in cell lines and in human primary macrophages. Importantly, we found that the Arl8b secretion pathway is crucial to control the type of cell death of the M. tuberculosis-infected macrophages. Indeed, Arl8b-depleted macrophages infected with avirulent H37Ra undergo necrotic instead of apoptotic cell death. These findings suggest that membrane repair mediated by Arl8b may be an important mechanism distinguishing avirulent from virulent M. tuberculosis-induced necrotic cell death.
Subject(s)
ADP-Ribosylation Factors/metabolism , Cell Membrane/metabolism , Lysosomes/metabolism , Macrophages/microbiology , Tuberculosis/metabolism , Apoptosis/physiology , Humans , Immune Evasion/physiology , Macrophages/metabolism , Mycobacterium tuberculosis/pathogenicity , Necrosis/metabolism , Necrosis/microbiology , Virulence/physiologyABSTRACT
Household contacts of pulmonary tuberculosis (TB) patients are at increased risk of TB infection and disease. However, their risk in relation to the intensity of exposure remains unknown.We studied smear-positive TB cases and their household contacts in Vitória, Brazil. We collected clinical, demographic and radiographic information from TB cases, and obtained tuberculin skin test (TST) and QuantiFERON-TB Gold (QFT) results from household contacts. We measured intensity of exposure using a proximity score and sleep location in relation to the TB index case and defined infection by TST ≥10â mm or QFT ≥0.35â UI·mL-1 We ascertained secondary TB cases by reviewing local and nationwide case registries.We included 160 TB index cases and 894 household contacts. 464 (65%) had TB infection and 23 (2.6%) developed TB disease. Risk of TB infection and disease increased with more intense exposures. In an adjusted analysis, the proximity score was associated with TB disease (OR 1.61, 95% CI 1.25-2.08; p<0.000); however, its diagnostic performance was only moderate.Intensity of exposure increased risk of TB infection and disease among household contacts; however, its diagnostic performance was still suboptimal. A biomarker to target preventive therapy is urgently needed in this at-risk population.
Subject(s)
Contact Tracing/methods , Tuberculosis, Pulmonary/transmission , Adult , Area Under Curve , Biomarkers/metabolism , Brazil , Communicable Disease Control , Family Characteristics , Female , Humans , Infectious Disease Medicine/methods , Interferon-gamma Release Tests , Male , Middle Aged , Mycobacterium tuberculosis , ROC Curve , Risk , Tuberculin Test/methods , Tuberculosis, Pulmonary/epidemiologyABSTRACT
BACKGROUND: Isoniazid preventive therapy (IPT) reduces tuberculosis reactivation and mortality among persons living with HIV (PLWH), yet hepatotoxicity concerns exclude "regular and heavy alcohol drinkers" from IPT. We aimed to determine the prevalence of elevated liver transaminases among PLWH on antiretroviral therapy (ART) who engage in alcohol use. SETTING: The Immune Suppression Syndrome Clinic of Mbarara, Uganda. METHODS: We defined elevated liver transaminases as ≥1.25 times (X) the upper limit of normal (ULN) for alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST). We evaluated the associations of current alcohol use and other variables of interest (sex, body mass index, and ART regimen) with elevated transaminases at study screening, using multivariable logistic regression to obtain adjusted odds ratios (aOR) and 95% confidence intervals (CI). RESULTS: Among 1301 participants (53% female, median age 39 years, 67.4% current alcohol use), 18.8% (95% CI: 16.8-21.1) had elevated transaminases pre-IPT, with few (1.1%) severe (≥5X the ULN). The proportion with any elevation among those currently using alcohol and those abstaining was 22.3% and 11.6%, respectively (p<0.01). In multivariable analyses, those currently using alcohol had higher odds of elevated transaminases compared to those abstaining (aOR 1.65, 95% CI 1.15-2.37) as did males compared to females (aOR 2.68, 95% CI 1.90-3.78). CONCLUSIONS: Pre-IPT elevated transaminases among PLWH receiving ART were common, similar to prior estimates, but severe elevations were rare. Current drinking and male sex were independently associated with elevated transaminases. Further research is needed to determine the implications of such transaminase elevations and alcohol use on providing IPT.
Subject(s)
Alcohol Drinking/adverse effects , Anti-HIV Agents/pharmacology , HIV Infections/drug therapy , Liver/enzymology , Transaminases/metabolism , Adolescent , Adult , Anti-HIV Agents/therapeutic use , Female , HIV Infections/complications , Humans , Liver/drug effects , Male , Middle Aged , Prevalence , UgandaABSTRACT
OBJECTIVE: Mycobacterium tuberculosis infection leads to latent or active tuberculosis (TB). Increased uptake on 18F-fluoro-2-deoxy-glucose-positron emission tomography/computed tomography (FDG-PET/CT) has been reported in the lungs and lymph nodes of individuals with recent infection and active TB, but not in individuals without known recent exposure or suggestive symptoms. We describe five patients with lung nodules not suspected to be due to TB in whom abnormalities on FDG-PET/CT scans ultimately were attributed to TB infection. RESULTS: Patient records were searched using the words "positron emission tomography/computed tomography" and 24 codes for TB between 2004 and 2013. Patients with a diagnosis of TB and a PET/CT scan were included. Clinical and radiographic data were retrieved. PET/CT images were reviewed by an experienced radiologist. FDG-PET/CT scans revealed elevated FDG-uptake in lungs of five patients subsequently diagnosed with active (n = 3) or clinically inactive (n = 2) tuberculosis. Uptake magnitude was unrelated to disease activity. These findings suggest that tuberculosis latency may include periods of percolating inflammation of uncertain relationship to future disease risk.
Subject(s)
Latent Tuberculosis/diagnostic imaging , Positron Emission Tomography Computed Tomography , Tomography, X-Ray Computed , Adult , Aged , Boston , Fluorodeoxyglucose F18 , HIV Infections , Humans , Male , Middle Aged , Positron-Emission Tomography , Radiopharmaceuticals , Retrospective StudiesABSTRACT
RePORT International is a collaborative research network of investigators from multiple countries and institutions with the goal of establishing a bio-repository of specimens and clinical data for the study of active TB and latent TB infection (LTBI). During the first meeting of RePORT International in Boston, Massachusetts, the results of research pertinent to TB control and eradication were presented, including advances in the research of Mycobacterium tuberculosis (MTB) persistence and drug resistance, TB diagnostics, drug and vaccine development.
Subject(s)
Biomedical Research/trends , Tuberculosis/prevention & control , Antitubercular Agents/pharmacology , Antitubercular Agents/therapeutic use , Biomedical Research/methods , Drug Discovery/methods , Drug Discovery/trends , Drug Resistance, Bacterial , Humans , Mycobacterium tuberculosis/drug effects , Translational Research, Biomedical/methods , Translational Research, Biomedical/trends , Tuberculosis/diagnosis , Tuberculosis VaccinesABSTRACT
Host- and pathogen-specific factors interplay with the environment in a complex fashion to determine the outcome of infection with Mycobacterium tuberculosis (Mtb), resulting in one of three possible outcomes: cure, latency or active disease. Although much remains unknown about its pathophysiology, latent tuberculosis infection (LTBI) defined by immunologic evidence of Mtb infection is a continuum between self-cure and asymptomatic, yet active tuberculosis (TB) disease. Strain virulence, intensity of exposure to the index case, size of the bacterial inoculum, and host factors such as age and co-morbidities, each contribute to where one settles on the continuum. Currently, the diagnosis of LTBI is based on reactive tuberculin skin testing (TST) and/or a positive interferon-gamma release assay (IGRA). Neither diagnostic test reflects the activity of the infectious focus or the risk of progression to active TB. This is a critical shortcoming, as accurate and efficient detection of those with LTBI at higher risk of progression to TB disease would allow for provision of targeted preventive therapy to those most likely to benefit. Host biomarkers may prove of value in stratifying risk of development of TB. New guidelines are required for interpretation of discordance between TST and IGRA, which may be due in part to a lack of stability (that is reproducibility) of IGRA or TST results or to a delay in conversion of IGRA to positivity compared to TST. In this review, the authors elaborate on the definition, diagnosis, pathophysiology and natural history of LTBI, as well as promising methods for better stratifying risk of progression to TB. The review is centered on the human host and the clinical and epidemiologic features of LTBI that are relevant to the development of new and improved diagnostic tools.