Positive Tuberculin Skin Test Research Articles

Prevalence of latent tuberculosis infection and associated risk factors among 1557 nursing students in a context of low endemicity.

Introduction:The risk of tuberculosis (TBC) in nurses is related to its incidence in the general population. Nursing students involved in clinical training could be exposed to occupational risks similar to those of healthcare workers (HCWs). To better understand the epidemiology of nosocomial TBC among nurses in a context of low endemicity, we recruited a cohort of young nursing trainees at the Second University of Naples.Methods: A screening programme for LTBI in nursing students was conducted between January 2012 and December 2013, at the Second University of Naples, with clinical evaluations, tuberculin skin test (TST) and, in positive TST student, the interferon-g release assays (IGRA). Putative risk factors for LTBI were assessed by a standardized questionnaire.Results: 1577 nursing students attending the Second University of Naples have been submitted to screening programme for TBC. 1575 have performed TST as first level test and 2 Quantiferon test (QFT). 19 students were TST positive and continued the diagnostic workup practicing QFT, that was positive in 1 student. Of the 2 subjects that have practiced QFT as first level test only 1 was positive. In 2 students positive to QFT test we formulated the diagnosis of LTBI by clinical and radiographic results.Conclusion: The prevalence of LTBI among nursing students in our study resulted very low. In countries with a low incidence of TBC, the screening programs of healthcare students can be useful for the early identification and treatment of the sporadic cases of LTBI.

Predicting the Development of Tuberculosis with the Tuberculin Skin Test and QuantiFERON Testing.

The identification of patients with latent tuberculosis infection, who are at higher risk to develop active disease, is an important component of disease control. We aim to compare the usefulness of the QuantiFERON-TB Gold in-tube assay and the tuberculin skin test to predict the development of active tuberculosis during follow-up, using positive and negative predictive values, positive likelihood ratios, and stratified level of risk. The study included contacts of tuberculosis cases diagnosed between 2007 and 2009. All contacts included were from the first circle of exposure. Tuberculin skin test and QuantiFERON test were performed and a chest radiograph was obtained during the contact's study. A total of 1,335 contacts were followed up for 4 years: a smear-positive index case was identified for 937 contacts, of whom 15 developed active tuberculosis and had initially presented with positive tuberculin skin test/QuantiFERON results, a normal chest radiograph, and no symptoms. The positive predictive value was 4% for QuantiFERON and 2% for the tuberculin skin test (when ≥5 mm). The probability of developing active disease was 2.36 times higher with a positive QuantiFERON, and 1.3 times higher with a positive tuberculin skin test. The positive predictive value was 17%, and the positive likelihood ratio was 7.53 for untreated contacts with a positive QuantiFERON. Stratifying according to initial QuantiFERON results showed a 6.36 times higher risk of developing active tuberculosis for patients with a QuantiFERON result greater than or equal to 10 IU/ml. Among bacillus Calmette-Guérin-vaccinated patients, a tuberculin skin test induration greater than or equal to 15 mm correlated better with a positive QuantiFERON. QuantiFERON results were more accurate than tuberculin skin test results in predicting tuberculosis. Although all contacts with QuantiFERON-positive results are at risk of developing tuberculosis, those with a tuberculin skin test induration greater than or equal to 15 mm and QuantiFERON greater than or equal to 10 IU/ml are at highest risk. This has important implications in the clinical management of tuberculosis contacts.

Incidence of occupational latent tuberculosis infection in South African healthcare workers.

The test-specific incidence of latent tuberculosis infection (LTBI) in healthcare workers from sub-Saharan Africa is unknown. 505 healthcare workers from South Africa were screened at baseline, and after 12 months, with a questionnaire, the tuberculin skin test (TST), and two T-cell assays (T-SPOT.TB and QuantiFERON-TB Gold-In-Tube). Test-specific conversion rates were calculated. The prevalence of presumed LTBI at baseline was 84, 69 and 62% using the TST, QuantiFERON-TB Gold-In-Tube and T-SPOT.TB, respectively. The annual test-specific conversion rate, depending on the cut-off point used, was as follows: TST 38%; QuantiFERON-TB Gold-In-Tube 13-22%; and T-SPOT.TB 18-22%. Annual reversion rates were 4, 7 and 16%, respectively. The annual TST conversion rate was significantly higher than that derived from published local community-based data (IRR 3.53, 95% CI 1.81-6.88). Factors associated with conversion (any test) included healthcare sector of employment, counselling of tuberculosis patients, and a baseline positive TST (for T-SPOT.TB). The annual rate of tuberculosis infection in South African healthcare workers was very high, irrespective of the testing method used, and may be explained by occupational exposure, as the rate was considerably higher than non-healthcare workers from the same community. Collectively, these data support the need for implementation of tuberculosis-specific infection control measures in Africa.

Risk for Tuberculosis Disease Among Contacts with Prior Positive Tuberculin Skin Test: A retrospective Cohort Study, New York City.

Patients with prior positive tuberculin skin test (TST) results may benefit from prophylaxis after repeat exposure to infectious tuberculosis (TB). To evaluate factors associated with active TB disease among persons with prior positive TST results named as contacts of persons with infectious TB. Population-based retrospective cohort study. A total of 2,933 contacts with prior positive TST results recently exposed to infectious TB identified in New York City's TB registry during the period from January 1, 1997 through December 31, 2003. Contacts developing active TB disease ≤ 4 years after exposure were identified and compared with those who did not, using Poisson regression analysis. Genotyping was performed on selected Mycobacterium tuberculosis-positive isolates. Among contacts with prior positive TST results, 39 (1.3 %) developed active TB disease ≤ 4 years after exposure (≤ 2 years: 34). Risk factors for contacts that were independently associated with TB were age < 5 years (adjusted prevalence ratio [aPR] = 19.48; 95 % confidence interval [CI] = 7.15-53.09), household exposure (aPR = 2.60;CI = 1.30-5.21), exposure to infectious patients (i.e., cavities on chest radiograph, acid-fast bacilli on sputum smear; aPR = 1.9 3; CI = 1.01-3.71), and exposure to a U.S.-born index patient (aPR = 4.04; CI = 1.95-8.38). Receipt of more than 1 month of treatment for latent TB infection following the current contact investigation was found to be protective (aPR = 0.27; CI = .08-0.93). Genotype results were concordant with the index patients among 14 of 15 contacts who developed active TB disease and had genotyping results available. Concordant genotype results and a high proportion of contacts developing active TB disease within 2 years of exposure indicate that those with prior positive TST results likely developed active TB disease from recent rather than remote infection. Healthcare providers should consider prophylaxis for contacts with prior TB infection, especially young children and close contacts of TB patients (e.g., those with household exposure).

Cost-effectiveness of alternative strategies for interferon-γ release assays and tuberculin skin test in tuberculous uveitis

BackgroundAlthough tuberculous uveitis remains a major cause of ocular morbidity in the developing world, there is no consensus on which diagnostic test or testing strategy is the most cost effective....

Differences in the Distribution of Peripheral Blood Leukocyte and Lymphocyte Subsets in Pulmonary Tuberculosis Patients

Abstract Introduction: It has been suggested that individuals exposed to Mycobacterium tuberculosis can eliminate the infection through the innate immune response without the participation of the acquired immunity. However, T helper type 1 immune response is critical to control persistent infection. Objective: The purpose of this study was to evaluate the distribution of leukocyte and lymphocyte subsets in peripheral blood of individuals with pulmonary tuberculosis (TB) and positive Tuberculin Skin Test (TST). Methodology: In order to achieve that goal, we have collected blood sample from thirty-four treatment-naive TB patients, fifty TST-positive and forty-one TST-negative individuals. Results: The evaluation has shown a significant reduction in the number of total lymphocytes, B cells, CD4+ and CD8+ T cells and percentage increase of NK cells, neutrophils and monocytes in TB patients, when compared to TSTpositive and TST-negative individuals. There was no statistical difference for leucocyte and lymphocyte subsets between TST-positive and TST-negative groups. Peripheral blood white cell counts change significantly at diagnosis. Conclusion: The quantification of these cells may support the diagnosis and monitoring of patients with pulmonary tuberculosis. Keywords: Leucocytes. Lymphocyte subsets. Tuberculosis.

Latent tuberculosis infection among a large cohort of medical students at a teaching hospital in Italy.

The surveillance of latent tuberculosis infection (LTBI) in both healthcare workers and healthcare students is considered fundamental for tuberculosis (TB) prevention. The aim of the present study was to estimate LTBI prevalence and evaluate potential risk-factors associated with this condition in a large cohort of medical students in Italy. In a cross-sectional study, performed between March and December 2012, 1511 eligible subjects attending the Medical School of the University of Genoa, trained at the IRCCS San Martino-IST Teaching Hospital of Genoa, were actively called to undergo the tuberculin skin test (TST). All the TST positive cases were confirmed with an interferon-gamma release assay (IGRA). A standardized questionnaire was collected for multivariate risk analysis. A total of 1302 (86.2%) students underwent TST testing and completed the questionnaire. Eleven subjects (0.8%) resulted TST positive and LTBI diagnosis was confirmed in 2 (0.1%) cases. Professional exposure to active TB patients (OR 21.7, 95% CI 2.9–160.2; P value 0.003) and previous BCG immunization (OR 28.3, 95% CI 3.0–265.1; P value 0.003) are independently associated with TST positivity. Despite the low prevalence of LTBI among Italian medical students, an occupational risk of TB infection still exists in countries with low circulation of Mycobacterium tuberculosis.

Expression pattern of transcription factors and intracellular cytokines reveals that clinically cured tuberculosis is accompanied by an increase in Mycobacterium-specific Th1, Th2, and Th17 cells.

Tuberculosis (TB) remains a major global health problem and is the second biggest cause of death by infectious disease worldwide. Here, we investigate in vitro the Th1, Th2, Th17, and Treg cytokines and transcriptional factors produced after Mycobacterium-specific antigen stimulation in patients with active pulmonary tuberculosis, clinically cured pulmonary tuberculosis, and healthy donors with a positive tuberculin skin test (TST+). Together, our data indicate that clinical cure after treatment increases the percentages of Mycobacterium-specific Th1, Th2, and Th17 cells compared with those found in active-TB and TST+ healthy donors. These results show that the host-parasite equilibrium in latent TB breaks in favor of the microorganism and that the subsequent clinical recovery posttreatment does not return the percentage levels of such cells to those observed in latent tuberculosis. Additionally, our results indicate that rather than showing an increase in the percentage of Mycobacterium-specific Tregs, active-TB patients display lower Th1 : Treg and Th17 : Treg ratios. These data, together with lower Th1 : Th2 and Th17 : Th2 ratios, may indicate a mechanism by which the breakdown of the host-parasite equilibrium leads to active-TB and changes in the repertoire of Mycobacterium-specific Th cells that are associated with clinical cure after treatment of pulmonary tuberculosis.

Sociodemographic, Epidemiological, and Clinical Risk Factors for Childhood Pulmonary Tuberculosis in Severely Malnourished Children Presenting With Pneumonia: Observation in an Urban Hospital in Bangladesh.

We aimed to evaluate sociodemographic, epidemiological, and clinical risk factors for pulmonary tuberculosis (PTB) in children presenting with severe acute malnutrition (SAM) and pneumonia. Children aged 0 to 59 months with SAM and radiologic pneumonia from April 2011 to July 2012 were studied in Bangladesh. Children with confirmed PTB (by culture and/or X-pert MTB/RIF) (cases = 27) and without PTB (controls = 81; randomly selected from 378 children) were compared. The cases more often had the history of contact with active PTB patient (P < .01) and exposure to cigarette smoke (P = .04) compared with the controls. In logistic regression analysis, after adjusting for potential confounders, the cases were independently associated with working mother (P = .05) and positive tuberculin skin test (TST; P = .02). Thus, pneumonia in SAM children is a common presentation of PTB and further highlights the importance of the use of simple TST and/or history of contact with active TB patients in diagnosing PTB in such children, especially in resource-limited settings.

Interferon-gamma release assay in a patient with tuberculosis verrucosa cutis.

Dear Editor: A 62-year-old man presented with an annular plaque that had been present for 35 years on his left inner thigh. Physical examination revealed a 7×8 cm annular erythematous plaque with central clearing and hyperpigmentation (Fig. 1). We suspected tinea cruris, granuloma annulare, and erythema annulare centrifugum, and performed a 4-mm punch biopsy. The pathologic examination of the specimen revealed parakeratosis, acanthosis in the epidermis, and naked granulomas in the upper to mid-dermis (Fig. 2). We also performed posteroanterior chest radiography, potassium hydroxide smear, acid-fast bacilli (AFB) stain, mycobacterial culture, periodic acid-Schiff stain, and tuberculosis polymerase chain reaction (TB-PCR), which were all negative. The tuberculin skin test (TST) showed a positive result; however, because the patient was a Korean with a history of tuberculosis vaccination, the specificity of the test was low. Therefore, we performed interferon-gamma release assay (IGRA), and the positive result of this test made us suspect a tuberculosis source of the granulomas. Considering the long duration and verrucous morphology of the lesion, as well as the histopathological and IGRA results, the diagnosis was concluded to be tuberculosis verrucosa cutis (TVC) and the patient was treated with multidrug antituberculosis medications for 6 months. A differential diagnosis with hypertrophic lupus vulgaris was difficult because both diseases are a form of paucibacillary cutaneous tuberculosis that could have similar clinical manifestations (verrucous plaque with central clearing) and a similar histopathology. The firm, rather than soft, consistency and the localization on the lower extremity favored the diagnosis of TVC. After the treatment, the clinical lesion disappeared, leaving slight postinflammatory hyperpigmentation and testing negative on IGRA. Fig. 1 A 7×8 cm annular erythematous plaque with central clearing and hyperpigmentation in the left inner thigh. Fig. 2 (A) Parakeratosis, acanthosis in epidermis and naked granulomas in the upper to mid-dermis (H&E, ×40). (B) Naked granulomas composed of epithelioid cells (H&E, ×200). TVC is a rare cutaneous tuberculosis. It results from external inoculation of mycobacteria into the skin of a previously infected person who has a moderate to high degree of immunity. Lesions progress slowly and persist for many years if left untreated1. The diagnosis of TVC traditionally requires clinicopathologic correlation with a positive TST or the detection of Mycobacterium tuberculosis DNA through PCR2. IGRA is a relatively new laboratory test; it measures the production of interferon-gamma by T cells exposed to certain antigens, including early secretory antigen target-6 and culture filtrate protein-10, which are specific for M. tuberculosis. Unlike TST, it is not affected by previous bacille Calmette-Guerin (BCG) vaccination or exposure to nontuberculous mycobacterium3. It is an improved diagnostic test for detecting tuberculosis infection, particularly in countries like Korea where BCG vaccinations have been widely used. Koh et al.4 reported the usefulness of IGRA in finding evidence of tuberculosis in tuberculid patients. We emphasize that IGRA can also be a good diagnostic aid in detecting evidence of tuberculosis in TVC. We experienced a case of TVC in the left inguinal area, in a Korean patient with a history of BCG vaccination. The patient had a normal chest radiograph, no mycobacterial growth in culture, a negative AFB stain, and a negative TB-PCR. However, IGRA and the purified protein derivative test were positive, which led us to conclude a diagnosis of TVC. We report the application and effectiveness of IGRA for the confirmation of TVC in countries where tuberculosis is prevalent.

Annual risk of tuberculous infection measured using serial skin testing, Orel Oblast, Russia, 1991-2005.

To compare trends in direct annual risk of tuberculous infection (ARTI) during 1991-2005 in relation to tuberculosis (TB) incidence and to indirect estimates of ARTI derived from the prevalence of tuberculin skin test (TST) positivity in schoolchildren in Orel Oblast, Russia. In 2005, we abstracted annual TST results and vaccination histories from a representative sample of schoolchildren in Orel Oblast, Russia, where bacille Calmette-Guerin (BCG) vaccination and annual TST of children are nearly universal. We calculated direct ARTI based on the percentage of children tested with TST conversions each year, excluding conversions following BCG vaccination. We analysed records from 13 206 children, with a median of 10 recorded TST results per child. The ARTI increased from 0.2% in 1991 to 1.6% in 2000, paralleling trends in TB incidence. Similar results were observed when the ARTI was estimated based on prevalence of infection among children aged 3-5 years using a 12 mm cut-off to define TST positivity. Results differed substantially when 10 or 15 mm cut-offs were used or when prevalence was determined among children aged 6-8 years. ARTI measured through TST conversion increased as TB incidence increased in Orel Oblast. ARTI measured through serial TSTs can thus provide an indicator of changing trends in TB incidence.

Tuberculosis

Tuberculosis (TB) resulted in 1.3 million deaths and 8.6 million new cases of active TB worldwide in 2012. Clinical manifestations of TB include fever, night sweats, weight loss, and cough. Latent infection is established by a positive tuberculin skin test or interferon-γ-release assay. Active TB disease is diagnosed by clinical, radiographic, and laboratory findings. Latent infection treatment is recommended in at-risk populations. The standard initial regimen for active disease includes rifampin, isoniazid, pyrazinamide, and ethambutol. Health-care providers are encouraged to consult with a TB specialist for assistance in the management of individuals with suspected or confirmed TB.

Broad adaptive immune responses to M. tuberculosis antigens precede TST conversion in tuberculosis exposed household contacts in a TB-endemic setting.

BackgroundThe identification of Mycobacterium-tuberculosis (Mtb) infected individuals remains a challenge due to an insufficient understanding of immune responses detected with the current diagnostic tests for latent tuberculosis i.e. the tuberculin skin test (TST) or IFN–γ release assays (IGRAs) and an inability to distinguish infection stages with current immunologic assays. Further classification based on markers other than IFN–γ may help to define markers of early Mtb infection.MethodsWe assessed the TST status of Mtb-exposed household contacts at baseline and at 6 months. Contacts were classified into those with initial positive TST (TST+); those with baseline negative TST but TST conversion at 6 months (TST converters, TSTC) and those with persistently negative TST (PTST−). We assessed their short- and long-term immune responses to PPD and ESAT–6/CFP–10 (EC) via IFN–γ ELISPOT and a multiplex cytokine array in relation to TST status and compared them to those of TB cases to identify immune profiles associated with a spectrum of infection stages.ResultsAfter 1 and 6 days stimulation with EC, 12 cytokines (IFN–γ, IL–2, IP–10, TNF–α, IL–13, IL–17, IL–10, GMCSF, MIP–1β, MCP–3, IL–2RA and IL–1A) were not different in TSTC compared to TST+ suggesting that robust adaptive Mtb-specific immune responses precede TST conversion. Stratifying contacts by baseline IFN–γ ELISPOT to EC in combination with TST results revealed that IP–10 and IL–17 were highest in the group of TST converters with positive baseline ELISPOT, suggesting they might be markers for recent infection.ConclusionWe describe a detailed analysis of Mtb-specific biomarker profiles in exposed household contacts in a TB endemic area that provides insights into the dynamic immune responses to Mtb infection and may help to identify biomarkers for ‘at-risk’ populations beyond TST and IGRA.

Tuberculin skin test positivity without tuberculosis contact: A major challenge in childhood.

Worldwide, tuberculin skin tests (TSTs) commonly give false positive results for those who had been given the Bacillus-Calmette-Guerin vaccine such as is routinely administered in Turkey. This study aimed to evaluate the patients referred to us who had positive TSTs despite lack of tuberculosis (TB) disease contacts. Between September 2011 and September 2012, 183 patients were prospectively evaluated for differential diagnosis of TST positivity despite lack of TB disease contact. They were then followed up by us to determine an accurate diagnosis. Among our patients' most common symptoms indicating a need for TST were chronic cough, productive cough or sputum expectoration, and recurrent or persistent wheezing. Chest x-rays were taken of all patients, and the findings were noted. Interferon gamma release assays were performed on 75% of the patients, of which 96% were negative for TB. The most common final diagnoses were asthma (44%), allergic rhinitis (13%), bronchopneumonia (11%) and reactive lymphadenitis (6.5%). Further evaluations for TB were required of 36 patients, and TB disease was established in 12 of them (6.5%). In patients who had had no known TB contact, the most common symptom indicating need for TST was chronic cough; the most common diagnoses were asthma and allergic rhinitis. Cavitary lesions, haemoptysis, persistent infiltration, pleural effusion and thoracic lymphadenopathy despite antibiotherapy should alert physicians to the possibility of TB.

Risk factors for latent tuberculosis infection in close contacts of active tuberculosis patients in South Korea: a prospective cohort study.

BackgroundThe diagnosis and treatment of latent tuberculosis infection (LTBI) have become mandatory to reduce the burden of tuberculosis worldwide. Close contacts of active TB patients are at high risk of both active and LTBI. The aim of this study is to identify the predominant risk factors of contracting LTBI, persons in close contact with TB patients were recruited. This study also aimed to compare the efficacy of the tuberculin skin test (TST) and QuantiFERON®-TB GOLD (QFT-G) to diagnose LTBI.MethodsClose contacts of active pulmonary TB patients visiting a hospital in South Korea were diagnosed for LTBI using TST and/or QFT-G. The association of positive TST and/or QFT-G with the following factors was estimated: age, gender, history of Bacillius Calmette-Guerin (BCG) vaccination, history of pulmonary TB, cohabitation status, the acid-fast bacilli smear status, and presence of cough in source cases.ResultsOf 308 subjects, 38.0% (116/305) were TST positive and 28.6% (59/206) were QFT-G positive. TST positivity was significantly associated with male gender (OR: 1.734; 95% CI: 1.001-3.003, p =0.049), history of pulmonary TB (OR: 4.130; 95% CI: 1.441-11.835, p =0.008) and household contact (OR: 2.130; 95% CI: 1.198-3.786, p =0.01) after adjustment for confounding variables. The degree of concordance between TST and QFT-G was fair (70.4%, κ =0.392).ConclusionsA prevalence of LTBI among close contacts of active pulmonary TB patients was high, and prior TB history and being a household contact were risk factors of LTBI in the study population.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0566-4) contains supplementary material, which is available to authorized users.

The tuberculin skin test in school going adolescents in South India: associations of socio-demographic and clinical characteristics with TST positivity and non-response.

BackgroundIndia has generally used 1 TU purified protein derivative (PPD) as opposed to 2 TU PPD globally, limiting comparisons. It is important to assess latent TB infection in adolescents given that they may be a target group for new post-exposure TB vaccines.The aim of this study is to describe the pattern and associations of tuberculin skin test (TST) responses (0.1 ml 2 TU) in adolescents in South India.Methods6643 school-going adolescents (11 to <18 years) underwent TST. Trained tuberculin reader made the reading visit between 48 and 96 hours after the skin testResultsOf 6608 available TST results, 9% had 0 mm, and 12% ≥10 mm responses. The proportion of TST positive (≥10 mm) was higher among older children, boys, those with a history of TB contact and reported BCG immunization Those with no TST response (0 mm) included younger participants (<14 years), those whose mothers were illiterate and those with a recent history of weight loss. Those of a higher socio-economic status (houses with brick walls, LPG gas as cooking fuel) and those with a visible BCG scar were less likely to be non-responders.ConclusionProportion of non-responders was lower than elsewhere in the world. Proportion of TST positivity was higher in those already exposed to TB and in children who had been BCG immunized, with a zero response more likely in younger adolescents and those with recent weight loss.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0571-7) contains supplementary material, which is available to authorized users.

The Usefulness of the Tuberculosis Skin Test and the Interferon-gamma Release Assay in the Diagnosis of Latent Tuberculosis Infection in South Korea

ObjectivesSouth Koreans receive the bacillus Calmette-Guerin (BCG) vaccination, which influence the result of the tuberculin skin test (TST); however, only a few studies have described the usefulness of the TST and interferon-γ release assay (IGRA) for diagnosing latent TB infection (LTBI). Therefore, our aim was to determine the usefulness of the TST and IGRA for diagnosing LTBI in a household contacts investigation. MethodsWe reviewed the 329 household contacts who visited Chung-Ang University Hospital (Seoul, Korea) from May 1, 2011 to February 28, 2014. To evaluate the effectiveness of TST and IGRA for the diagnosis of LTBI, we examined the concordance rate between the two tests, based on age. We also evaluated the risk factors for LTBI. ResultsThe concordance rate between the two tests in individuals 0–24 years, 25–54 years, and over 55 years were 82.6% (κ = 0.64, p < 0.01), 68.9% (κ = 0.40, p < 0.01), and 68.4% (κ = 0.35, p < 0.01), respectively. The ratio of positive TST to negative IGRA was higher in individuals 25–44 years old, whereas the ratio of negative TST to positive IGRA was higher in individuals older than 55 years old. Based on the TST, the risk factor for LTBI was a cavity (p < 0.01). When using IGRA, the risk factors were contact time (p = 0.04) and age over 55 years old (p = 0.02). ConclusionThe concordance rate between TST and IGRA was not good after the age of 25 years. The IGRA test reflects the known risk factors more exactly.

Screening of latent tuberculosis infection by interferon-γ release assays in rheumatic patients: a systemic review and meta-analysis.

The aim of this study is to assess the diagnostic value of interferon-γ release assays (IGRAs) for latent tuberculosis infection (LTBI) in patients with rheumatic disease before receiving biologic agents. MEDLINE and EMBASE databases were used for searching studies concerning the evaluation on the performance of IGRAs [QuantiFERON-TB Gold (QFT-G), QuantiFERON-TB Gold In-Tube (QFT-GIT) and T-SPOT.TB] in rheumatic patients before biological therapy. After assessing the quality of all studies included in the review, we summarized the results in subgroups using forest plots and calculated pooled estimates if applicable. The search identified 11 studies with a total sample size of 1940 individuals. Compared with the tuberculin skin test (TST), the pooled agreements in QFT-G/GIT and T-SPOT.TB were 72 % (95 % confidence interval (CI) 65, 78 %) and 75 % (95 % CI 67, 83 %), respectively. BCG vaccination was positively correlated with positive rates of TST (pooled odds ratio (OR) 1.64, 95 % CI 1.06, 2.53). Compared with TST, IGRAs were better associated with the presentence of one or more tuberculosis (TB) risk factors. Neither steroid nor disease-modifying anti-rheumatic drugs (DMARDs) significantly affect positive IGRA results. In contrast, TST positivity was significantly impacted by the use of steroid (pooled OR 0.45, 95 % CI 0.30, 0.69), but less significantly by the use of DMARDs (pooled OR 0.78, 95 % CI 0.50, 1.21). In conclusion, in rheumatic patients with previous BCG vaccination or currently on steroid therapy, IGRAs would be the better choice to identify LTBI by decreasing the false-positivity and false-negativity rate compared with conventional TST.

Long-term protection from isoniazid preventive therapy for tuberculosis in HIV-infected patients in a medium-burden tuberculosis setting: the TB/HIV in Rio (THRio) study.

The duration of protection against tuberculosis provided by isoniazid preventive therapy is not known for human immunodeficiency virus (HIV)-infected individuals living in settings of medium tuberculosis incidence. We conducted an individual-level analysis of participants in a cluster-randomized, phased-implementation trial of isoniazid preventive therapy. HIV-infected patients who had positive tuberculin skin tests (TSTs) were followed until tuberculosis diagnosis, death, or administrative censoring. Nelson-Aalen cumulative hazard plots were generated and hazards were compared using the log-rank test. Cox proportional hazards models were fitted to investigate factors associated with tuberculosis diagnosis. Between 2003 and 2009, 1954 patients with a positive TST were studied. Among these, 1601 (82%) initiated isoniazid. Overall tuberculosis incidence was 1.39 per 100 person-years (PY); 0.53 per 100 PY in those who initiated isoniazid and 6.52 per 100 PY for those who did not (adjusted hazard ratio [aHR], 0.17; 95% confidence interval [CI], .11-.25). Receiving antiretroviral therapy at time of a positive TST was associated with a reduced risk of tuberculosis (aHR, 0.69; 95% CI, .48-1.00). Nelson-Aalen plots of tuberculosis incidence showed a constant risk, with no acceleration in 7 years of follow-up for those initiating isoniazid preventive therapy. Isoniazid preventive therapy significantly reduced tuberculosis risk among HIV-infected patients with a positive TST. In a medium-prevalence setting, 6 months of isoniazid in HIV-infected patients with positive TST reduces tuberculosis risk over 7 years of follow-up, in contrast to results of studies in higher-burden settings in Africa.

Cigarette smoking among tuberculosis patients increases risk of transmission to child contacts.

Observational cohort study in Lima, Peru. To determine the association between exposure to a smoking tuberculosis (TB) case and latent tuberculous infection (LTBI). Between September 2009 and August 2012, we identified 2132 patients with drug-susceptible TB and their 2054 child household contacts. Data were collected on active and secondhand smoking status and other risk factors for infection specific to the index case, the household and the exposed contacts. Contacts underwent a tuberculin skin test (TST) to determine their tuberculous infection status at baseline, 6-month and 12-month follow-up. We estimated the association between exposure to a smoking index case and LTBI using a modified Poisson regression model. The 21 children (age ⩿15 years) exposed to smoking index TB patients were more likely to be TST-positive at baseline (RR 2.64, 95%CI 1.78-3.91), by 6 months (RR 1.91, 95%CI 1.40-2.60) and by 12 months (RR 1.48, 95%CI 1.07-2.06), than those who were not exposed. TST positivity among children at these time points did not vary with secondhand smoke exposure. TB patients who smoke may be more likely to transmit infection to their contacts. Interventions designed to reduce smoking among TB patients may minimise further spread of the disease.