Tuberculosis and Other Mycobacterial Infections

2019 ◽  
Author(s):  
Simon Tiberi
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Sputum Sample ◽  
Interferon Γ ◽  
Sputum Smear ◽  
Rapid Progression ◽  
Course Of Illness ◽  
Mycolic Acids ◽  
Latent Tb Infection ◽  
The Uk ◽  
Factor Α

Mycobacterium tuberculosis (MTB) is a thin, aerobic, non-spore forming, slow-growing (doubling time twelve hours) non-motile rod-shaped bacteria, belonging to the family Mycobacteriaceae. Mycobacterium tuberculosis complex is made up of several species, including M. tuberculosis, M. bovis, Bacillus Calmette-Guerin (BCG), M. africanum, M. canetii, M.caprae, M. microti, and others. Transmission is via inhalation of aerosolized respiratory secretions. After inhalation, majority of bacilli are captured in the upper respiratory tract by mucus and removed through a process called clearance, although bacteria in small droplets can reach the alveoli where the bacilli are ingested by macrophages. If clearance is not effective infection may result. With the involvement of CD4 lymphocytes, interferon-γ and tumour necrosis factor-α, a granuloma is formed, and bacilli may be destroyed. In many cases, the bacilli are not destroyed and can spread into lymphatics or via blood to other sites (any organs) where it can lie dormant for years. This asymptomatic situation is called latent TB infection (LTBI). It may reactivate in 10% of people throughout their lifetime; this increases with immunosuppression and HIV infection. The course of illness is chronic and indolent. However, rapid progression to fulminant disease may result if the host is immunocompromised. Pulmonary TB is the most common and important form of TB because it is the infectious form of the disease. In areas where reactivation predominates (like the UK), there is a higher proportion of extrapulmonary TB. Tuberculosis bacilli resist destaining with acid alcohol treatment hence the term. This retention is due to complexing of the carbolfuschin Ziehl-Neelsen stain with mycolic acids present in the waxy cell wall, including lipoarabinomannan (which facilitates survival in macrophages). Microscopy will diagnose TB in 80% of smear-positive patients with a first sputum sample, a further 15% with the second, and 5% with a third. In endemic areas finding acid-fast bacilli in sputum has a 98% specificity, but this is not the case in the UK, a low-prevalence setting, where atypical mycobacteria can have a similar prevalence. In the best settings only 60% of culture-positive patients are also sputum smear-positive as liquid culture, the gold standard, and most sensitive test.

scholarly journals Evaluation of Gamma Interferon Release Assays Using Mycobacterium tuberculosis Antigens for Diagnosis of Latent and Active Tuberculosis in Mycobacterium bovis BCG-Vaccinated Populations

2010 ◽  
Vol 17 (12) ◽  
pp. 1985-1990 ◽  
Author(s):  
Shu Zhang ◽  
Lingyun Shao ◽  
Ling Mo ◽  
Jiazhen Chen ◽  
Feifei Wang ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Mycobacterium Bovis ◽  
Gamma Interferon ◽  
Sputum Smear ◽  
Purified Protein Derivative ◽  
Tb Treatment ◽  
Latent Tb ◽  
Specific Antigens ◽  
Latent Tb Infection

ABSTRACT T-cell-based gamma interferon (IFN-γ) release assays (IGRAs) using Mycobacterium tuberculosis-specific antigens have shown higher sensitivity and specificity than the routine tuberculin skin test (TST). However, the effects of Mycobacterium bovis BCG vaccination and anti-tuberculosis (TB) treatment on dynamic T-cell responses to M. tuberculosis-specific antigens in active TB cases have rarely been investigated in regions where TB is endemic. Eighty-nine patients with active pulmonary TB (ATB) and 57 healthy controls (HC) from China were recruited and tested by sputum smear and culture, TSTs, and IGRAs with M. tuberculosis-specific antigens ESAT-6 and CFP-10 (T-SPOT.TB) as well as purified protein derivative (PPD) stimulation. All 146 participants were screened by the T-SPOT.TB assay at recruitment. T-SPOT.TB-positive rates in ATB and HC groups were 87.6% (78/89) and 21.1% (12/57), respectively. Of 38 ATB patients who were both TST and T-SPOT.TB tested, the positive rates were 73.7% (28/38) and 94.7% (36/38), respectively (P = 0.0215), and those in the HC group were 62.3% (33/53) and 18.9% (10/53), respectively (P < 0.0001). The T-SPOT.TB-positive rates declined during TB treatment and were 94.4% (51/54), 86.4% (19/22), and 61.5% (8/13) for ATB patients receiving 0- to 1-month, 1- to 3-month, and 3- to 6-month anti-TB treatment, respectively. The IGRA is a most promising test for both active TB and latent TB infection (LTBI) diagnosis due to the improvement of its specificity and convenience, especially in the Mycobacterium bovis BCG-vaccinated population. Furthermore, the T-SPOT.TB assay using ESAT-6 and CFP-10 in ATB patients during anti-TB treatment could serve as a potential predictor of therapeutic efficacy.

scholarly journals Recent Progress in Diagnosis Methods for Latent Tuberculosis Infection and Its Clinical Applications

2015 ◽  
Vol 4 (3) ◽  
pp. 69-74
Author(s):  
Ling Zhou
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Recent Progress ◽  
Latent Tuberculosis Infection ◽  
Latent Tuberculosis ◽  
Interferon Γ ◽  
Clinical Applications ◽  
Active Tuberculosis ◽  
Advantages And Disadvantages ◽  
Latent Tb ◽  
Latent Tb Infection

AbstractMost people with latentMycobacterium tuberculosisinfection can partly develop active tuberculosis (TB). Therefore, diagnosis of this condition bears significance in early TB prevention. To date, the main methods for diagnosis of latent TB infection (LTBI) include tuberculin skin test and interferon γ release test. These two methods feature their own advantages and disadvantages. Although new diagnostic markers continually emerge, no uniform diagnostic criteria are available for TB detection. This study summarizes several methods for diagnosis of LTBI and new related markers and their application value in clinical practice.

scholarly journals Molecular detection of Mycobacterium tuberculosis from buccal swabs among adult in Peru

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Annelies W. Mesman ◽  
Roger I. Calderon ◽  
Nira R. Pollock ◽  
Martín Soto ◽  
Milagros Mendoza ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Sputum Sample ◽  
Patient Characteristics ◽  
Sputum Smear ◽  
Buccal Swab ◽  
Sample Type ◽  
Sample Collection ◽  
Safe Alternative ◽  
Fta Cards ◽  
Cavitary Disease

AbstractTuberculosis (TB) diagnosis relies on a sputum sample, which cannot be easily obtained from all symptomatic patients. Mycobacterium tuberculosis DNA can be detected from oral swabs, a noninvasive, safe alternative sample type; however, reported sensitivities have been variable and likely depend on sample collection, processing procedures and host characteristics. We analyzed three buccal swab samples from 123 adults with culture-confirmed TB in Lima, Peru. We compared the sensitivity and specificity of two sample collection devices (OmniSwab and EasiCollect FTA cards) and examined factors associated with detection. DNA was extracted with a commercially available kit and detected via real-time PCR IS6110 amplification. Overall sensitivity for buccal samples was 51% (95% Confidence Interval [CI] 42–60%). Specificity from a single sample among healthy controls was 96.7% (95% CI 83–99.9%). Positive sputum smear and cavitary disease, correlates of disease burden, were associated with detection via buccal swab. Although we observed higher sensitivities with the Omniswab samples, this appeared to be due primarily to differences in patient characteristics (e.g., cavitary disease). Overall, our findings support the potential for a buccal sample-based TB assay. Future work should focus on assay optimization and streamlining the assay workflow.

Comparison of Screening Procedures for Mycobacterium tuberculosis Infection Among Patients with Inflammatory Diseases

2009 ◽  
Vol 36 (9) ◽  
pp. 1876-1884 ◽  
Author(s):  
BOLETTE SOBORG ◽  
MORTEN RUHWALD ◽  
MERETE LUND HETLAND ◽  
SØREN JACOBSEN ◽  
AASE BENGAARD ANDERSEN ◽  
...  
Keyword(s):  
Risk Factors ◽  
Mycobacterium Tuberculosis ◽  
Inflammatory Diseases ◽  
Interferon Γ ◽  
Mycobacterium Tuberculosis Infection ◽  
Tb Treatment ◽  
Latent Tb ◽  
Latent Tb Infection ◽  
High Degree

Objective.To test if Mycobacterium tuberculosis screening results differ among patients with inflammatory disease depending on whether the QuantiFeron TB-Gold test (QFT) or tuberculin skin test (TST) is used; and to evaluate if a possible difference is influenced by the presence of risk factors or immunosuppression.Methods.The interferon-γ response to in vitro stimulation of M. tuberculosis-specific antigens was measured with QFT and results were compared with TST. Associations to bacillus Calmette-Guerin (BCG) vaccination, risk factors, and immunosuppression were analyzed for both tests.Results.QFT and TST results were available for 294/302 and 241/302 patients, respectively; 234 had results from both tests. Twenty-one (7%) tested positive with QFT and 45 (19%) with TST. A positive QFT was associated with risk factors for M. tuberculosis infection: i.e., birth or upbringing in a TB-endemic area [risk ratio (RR) = 7.8, 95% CI 1.5–18.2, p < 0.001], previous TB treatment (RR 4.7, 95% CI 1.6–13.5, p = 0.005), and any latent TB infection risk factor (RR 4.7, 95% CI 2.1–11.0, p = 0.0002). Treatment with corticosteroids increased the risk for an inconclusive QFT result (RR 4.2, 95% CI 1.6–10.7, p = 0.04) and decreased the risk for a positive TST result (RR 0.4, 95% CI 0.1–1.0, p = 0.04). Agreement between the tests was low (kappa 0.2, 95% CI 0.02–0.3, p = 0.002).Conclusion.The study documented a high degree of discordant positive QFT and TST results. A positive QFT was more closely associated with risk factors for M. tuberculosis infection than the TST. The use of corticosteroids affected test outcome by increasing the risk for an inconclusive QFT result and decreasing the risk for a positive TST result.

scholarly journals Longitudinal Mycobacterium tuberculosis specific interferon-γ responses in Ethiopian HIV-negative women during pregnancy and post-partum

2021 ◽  
Author(s):  
Fregenet Tesfaye ◽  
John Walles ◽  
Erik Sturegård ◽  
Niclas Winqvist ◽  
Taye Tolera Balcha ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Post Partum ◽  
Interferon Γ ◽  
Inclusion Criteria ◽  
Dynamic Changes ◽  
Cellular Immune Responses ◽  
Latent Tb ◽  
Latent Tb Infection ◽  
Cellular Immune ◽  
Hiv Negative

Background: Pregnancy may influence cellular immune responses to Mycobacterium tuberculosis (Mtb). We investigated Mtb-specific interferon-γ responses in women followed longitudinally during pregnancy and post-partum. Methods: Interferon-γ levels (stimulated by Mtb antigens [TB1 and TB2] and mitogen included in the QuantiFERON-TB Gold Plus assay) were measured in blood from pregnant HIV-negative women identified from a prospective cohort at Ethiopian antenatal care clinics. Longitudinal comparisons included women without active TB with Mtb-triggered interferon-γ responses ≥0.20 IU/ml, sampled on two and/or three occasions (1 st /2 nd trimester, 3 rd trimester and 9 months post-partum). Results: Among 2093 women in the source cohort, 363 met inclusion criteria for longitudinal comparisons of Mtb-stimulated interferon-γ responses. Median Mtb-triggered interferon-γ concentrations were higher at 3 rd compared to 1 st /2 nd trimester (in 38 women with samples available from these timepoints; TB1: 2.8 vs 1.6 IU/ml, p=0.005; TB2: 3.3 vs 2.8 IU/ml, p=0.03) and post-partum (in 49 women with samples available from these timepoints; TB1: 3.1 vs 2.2 IU/ml, p=0.01; TB2: 3.1 vs 2.3 IU/ml, p=0.03). In contrast, mitogen-stimulated interferon-γ levels were lower at 3 rd compared with 1 st /2 nd trimester (in 32 women with samples available from these timepoints: 21.0 vs 34.9 IU/ml, p=0.02). Results were similar in 22 women sampled on all three occasions. Conclusions: In HIV-negative women, Mtb-stimulated interferon-γ responses were higher during the 3 rd trimester compared to earlier stages of pregnancy and post-partum, despite decreased mitogen-triggered responses. These findings suggest increased Mtb-specific cellular responses due to dynamic changes of latent TB infection during pregnancy.

scholarly journals Management of childhood and adolescent latent tuberculous infection (LTBI) in Germany, Austria and Switzerland

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0250387
Author(s):  
Ulrich von Both ◽  
Philipp Gerlach ◽  
Nicole Ritz ◽  
Matthias Bogyi ◽  
Folke Brinkmann ◽  
...  
Keyword(s):  
Health Sector ◽  
Final Analysis ◽  
Interferon Γ ◽  
Rapid Progression ◽  
Tuberculous Infection ◽  
X Ray ◽  
Release Assay ◽  
Chest X Ray ◽  
Low Incidence ◽  
Latent Tb Infection

Background Majority of active tuberculosis (TB) cases in children in low-incidence countries are due to rapid progression of infection (latent TB infection (LTBI)) to disease. We aimed to assess common practice for managing paediatric LTBI in Austria, Germany and Switzerland prior to the publication of the first joint national guideline for paediatric TB in 2017. Methods Online-based survey amongst pediatricians, practitioners and staff working in the public health sector between July and November 2017. Data analysis was conducted using IBM SPSS. Results A total of 191 individuals participated in the survey with 173 questionnaires included for final analysis. Twelve percent of respondents were from Austria, 60% from Germany and 28% from Switzerland. Proportion of children with LTBI and migrant background was estimated by the respondents to be >50% by 58%. Tuberculin skin test (TST) and interferon-γ-release-assay (IGRA), particularly Quantiferon-gold-test, were reported to be used in 86% and 88%, respectively. In children > 5 years with a positive TST or IGRA a chest x-ray was commonly reported to be performed (28%). Fifty-three percent reported to take a different diagnostic approach in children ≤ 5 years, mainly combining TST, IGRA and chest x-ray for initial testing (31%). Sixty-eight percent reported to prescribe isoniazid-monotherapy: for 9 (62%), or 6 months (6%), 31% reported to prescribe combination therapy of isoniazid and rifampicin. Dosing of isoniazid and rifampicin below current recommendations was reported by up to 22% of respondents. Blood-sampling before/during LTBI treatment was reported in >90% of respondents, performing a chest-X-ray at the end of treatment by 51%. Conclusion This survey showed reported heterogeneity in the management of paediatric LTBI. Thus, regular and easily accessible educational activities and national up-to-date guidelines are key to ensure awareness and quality of care for children and adolescents with LTBI in low-incidence countries.

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