IGRA Results Research Articles

Epidemiology and Clinical Characteristics of Ocular Tuberculosis in the United States, 1993-2019.

Data regarding ocular tuberculosis (OTB) in the United States have not been previously reported. We evaluated trends of OTB compared with other extrapulmonary TB (EPTB). We estimated the proportion of all EPTB cases (with or without concurrent pulmonary involvement) with OTB reported to the National Tuberculosis Surveillance System during 1993-2019. We compared demographics and clinical characteristics of people with OTB and other EPTB during 2010-2019. P values were calculated by chi-square test for categorical variables and Kruskal-Wallis for continuous variables. During 1993-2019, 1766 OTB cases were reported, representing 1.6% of 109 834 all EPTB cases: 200 (0.5% of 37 167) during 1993-1999, 395 (1.0% of 41 715) during 2000-2009, and 1171 (3.8% of 30 952) during 2010-2019. In contrast to persons with other EPTB, persons with OTB were older (median, 48 vs 44 years; P < .01), more likely to be US-born (35% vs 28%; P < .01), more likely to have diabetes (17% vs 13%; P < .01), and less likely to have HIV (1% vs 8%; P < .01). OTB was less likely to be laboratory confirmed (5% vs 75%; P < .01), but patients were more likely to be tested by interferon gamma release assay (IGRA; 84% vs 56%; P < .01) and to be IGRA positive (96% vs 80%; P < .01). Reported OTB increased during 1993-2019 despite decreasing TB, including EPTB; the largest increase occurred during 2010-2019. OTB was rarely laboratory confirmed and was primarily diagnosed in conjunction with IGRA results. More research is needed to understand the epidemiology of OTB to inform clinical and diagnostic practices.

Interferon-gamma release assay for screening of tuberculosis infection in children

BackgroundInterferon-gamma release assay (IGRA) is the main tool for the diagnosis of latent tuberculosis (TB) infection (LTBI). However, the indeterminate results were more frequent in children, and the underlying reasons were largely speculative. We aimed to compare QuantiFERON-TB Gold In-Tube (QFT-GIT) with X.DOT-TB (XDOT) for diagnosing LTBI, and to identify the risk factors associated with indeterminate results in children.MethodsA retrospective study for children<18 years old, at risk for LTBI or progression to TB disease, received either QFT-GIT or X.DOT-TB tests was performed at Beijing Children’s Hospital from August 2019 to August 2022.ResultsA total of 33,662 children were recruited, including 15,129 (44.9%) tested with X.DOT-TB and 18,533 (55.1%) with QFT-GIT. Proportion of positive and indeterminate results in children with respiratory disease was significantly higher than did that with other diseases, respectively (P < 0.001). The indeterminate rate of X.DOT-TB and QFT-GIT results decreased with increasing age (P < 0.001). Proportion of QFT-GIT indeterminate results was higher than that of X.DOT-TB across age groups. Male, age and disease classification all presented a statistically significant association with indeterminate IGRA results.ConclusionsThe positive rates of X.DOT-TB and QFT-GIT in children were 3.1% and 1.8%, respectively. The X.DOT-TB assay performed better than QFT-GIT in children, and male, age and underlying diseases were associated with an increased risk of indeterminate IGRA results.

Outcomes and Challenges in the Programmatic Implementation of Tuberculosis Preventive Therapy among Household Contacts of Pulmonary TB Patients: A Mixed-Methods Study from a Rural District of Karnataka, India.

The National TB Elimination Programme (NTEP) of India is implementing tuberculosis preventive treatment (TPT) for all household contacts (HHCs) of pulmonary tuberculosis patients (index patients) aged <5 years and those HHCs aged >5 years with TB infection (TBI). We conducted an explanatory mixed-methods study among index patients registered in the Kolar district, Karnataka during April-December 2022, to assess the TPT cascade and explore the early implementation challenges for TPT provision. Of the 301 index patients, contact tracing home visits were made in 247 (82.1%) instances; a major challenge was index patients' resistance to home visits fearing stigma, especially among those receiving care from the private sector. Of the 838 HHCs, 765 (91.3%) were screened for TB; the challenges included a lack of clarity on HHC definition and the non-availability of HHCs during house visits. Only 400 (57.8%) of the 692 eligible HHCs underwent an IGRA test for TBI; the challenges included a shortage of IGRA testing logistics and the perceived low risk among HHCs. As HHCs were unaware of their IGRA results, a number of HHCs actually eligible for TPT could not be determined. Among the 83 HHCs advised of the TPT, 81 (98%) initiated treatment, of whom 63 (77%) completed treatment. Though TPT initiation and completion rates are appreciable, the NTEP needs to urgently address the challenges in contact identification and IGRA testing.

Host factors associated with false negative results in an interferon‐γ release assay in adults with active tuberculosis

ObjectiveTo identify host factors associated with false-negative results of interferon-γ release tests in adults with active tuberculosis. MethodsThe clinical data of 943 patients with active tuberculosis diagnosed by acid-fast smear staining, Mycobacterium tuberculosis culture, Mycobacterium tuberculosis PCR and pathological examination at West China Hospital of Sichuan University were retrospectively analysed. According to the results of the interferon γ release test (IGRA), the patients were divided into the IGRA− group and IGRA+ group. Logistic regression was used to analyze the sociodemographic data and clinical characteristics of participants in the IGRA− group and IGRA+ group. ResultsAmong 943 patients with active tuberculosis, 174 (18.5 %) were IGRA negative (false negative), and 769 (81.5 %) were IGRA positive. Multivariate logistic regression analysis identified the following characteristics independently associated with IGRA negativity: age (OR: 1.02; 95 % CI: 1.01 1.03; p = 0.006), anti-tuberculosis treatment >1 month (OR: 1.68; 95 % CI: 1.12 2.52; p = 0.013), HIV infection (OR: 9.48; 95 % CI: 3.23 27.85; p = 0.000), combined with connective tissue diseases (OR: 2.78; 95 % CI: 1.30 5.94; p = 0.008) and low hemoglobin (OR: 0.99; 95 % CI: 0.98 1.00; p = 0.044) was associated with an increased false-negative probability of IGRA. ConclusionAge, anti-tuberculosis therapy >1 month, coinfection with HIV, coassociated connective tissue disease and decreased hemoglobin were identified as risk factors for false-negative results of IGRA. Our results suggest a careful interpretation of IGRA in adults with these characteristics.

Specific and non-specific effects of Mycobacterium bovis BCG vaccination in dairy calves.

Bovine tuberculosis (bTB) is a chronic disease mainly caused by Mycobacterium bovis, a zoonotic pathogen with economic significance as it leads to reduced milk and meat production, and high costs for control measures. The Bacillus Calmette-Guérin (BCG) vaccine, primarily used to prevent tuberculosis in humans, has also been studied for controlling bTB. While showing effectiveness in preventing M. bovis infection and disease in cattle, the BCG vaccine can induce non-specific effects on the immune system, enhancing responses to infections caused by unrelated pathogens, and also having non-specific effects on lactation. The aim of this study is to describe both the specific and non-specific effects of BCG vaccination in calves from a commercial dairy herd in central Chile. Diagnosis of M. bovis infection was performed through the IFNγ release assay (IGRA) using ESAT6/CFP-10 and Rv3615c antigens. The records of milk production, somatic cell count (SCC), clinical mastitis (CM) and retained placenta (RP) during the first lactation were compared between vaccinated and non-vaccinated animals. The breed (Holstein Friesian [HF] v/s HF × Swedish Red crossbred [HFSR]) and the season (warm v/s cold) were also analyzed as categorical explanatory variables. Results of IGRA showed significant differences between vaccinated and control groups, indicating a vaccine efficacy of 58.5% at 18 months post vaccination in HFSR crossbred animals. Although milk production did not vary, SCC and CM showed differences between groups, associated to the breed and the season, respectively. When analyzing CM and RP as a whole entity of disease, BCG showed protection in all but the cold season variables. Overall, the BCG vaccine induced protective specific and non-specific effects on health parameters, which may be influenced by the breed of animals and the season. These results provide new features of BCG protection, supporting initiatives for its implementation as a complementary tool in bTB control.

Influence of age, IGRA results, and inflammatory markers on mortality in hospitalized tuberculosis patients

IntroductionTuberculosis (TB) remains a leading cause of death globally. Identifying the factors associated with mortality during hospitalization for TB is crucial for improving patient outcomes. This study aimed to investigate the potential risk factors, including T-SPOT.TB test results and routine laboratory markers of inflammation, associated with death during hospitalization due to TB. MethodsA retrospective analysis was conducted on 244 hospitalized TB patients. Demographic data, clinical characteristics, T-SPOT.TB results, and laboratory parameters were collected. Univariate and multivariate analyses were performed to identify independent risk factors for in-hospital mortality. ResultsAmong the patients, 206 survived and 38 died during hospitalization. Multivariate analysis revealed that age (HR: 1.08, 95% CI: 1.02–1.15, p = 0.001), a negative T-SPOT.TB test result (HR: 4.01, 95% CI: 1.78–9.01, p < 0.001), elevated C-reactive protein (CRP) levels (HR: 1.04, 95% CI: 1.01–1.08, p = 0.007), and increased neutrophil-to-lymphocyte ratio (NLR) (HR: 1.04, 95% CI: 1.00–1.07, p = 0.025) were independent risk factors for mortality. ConclusionsThis study identified age, a negative T-SPOT.TB result, elevated CRP levels, and a high NLR as significant independent risk factors for death in hospitalized TB patients. These findings underscore the importance of these parameters in the risk stratification and management of hospitalized TB patients. Further research is warranted to elucidate the mechanisms behind these associations and to validate these results in different populations.

TUBERCULIN SKIN TEST AND INTERFERON-γ RELEASE ASSAY ON THE DIAGNOSIS OF TUBERCULOUS SPONDYLITIS

Highlights TST and IGRA have a significant correlation with the diagnosis of patients with Tuberculous Spondylitis. Various factors may affect the results of TST and IGRA. Thus, the use of TST and IGRA can be adjusted according to the condition of the hospital, the availability of diagnostic tools, the health worker’s physical examination results, and the patient's medical history. Abstract Background: Tuberculous spondylitis or Pott’s disease is extrapulmonary tuberculosis that is still a concern to health workers because of the broad spectrum of its clinical symptoms. Delay in diagnosis is very common in this disease. Therefore, its diagnostic tool needs to be thoroughly reviewed to determine its effectiveness. The diagnostic tools studied in this study were Tuberculin Skin Test (TST) and Interferon-γ Release Assay (IGRA). Objective: To analyze the role of TST and IGRA as diagnostic tools for the diagnosis of tuberculous spondylitis. Material and Method: This study used a systematic review method to analyze topic-related kinds of literature written in English and Indonesian found on PubMed, Scopus, ProQuest, and Web of Science databases. The literature screening process was carried out based on the PRISMA 2020 Guidelines. Result: Sixteen types of literature were included for a total of 116 patients. TST was detected positive in 45 (63%) and negative in 21 (30%) of a total of 66 patients with Pott’s disease. IGRA was detected positive in 51 (77%), negative in 8 (12%), and indeterminate in 2 (3%) of a total of 61 patients with Pott’s disease. Conclusion: TST and IGRA results significantly correlate with the diagnosis of tuberculous spondylitis. Both tests are still relevant for use in the diagnosis of the disease. IGRA and TST are used according to the needs of health workers and patients’ health backgrounds.

P42 Are chest X-rays still necessary for prebiologic tuberculosis screening? A retrospective audit

Abstract Biologics are commonly used in autoimmune dermatological conditions as an option if other treatments are unsuccessful or contraindicated. However, one major side-effect of biologics is immunosuppression, which may lead to the reactivation of latent tuberculosis (TB) in patients. The British Association of Dermatology has implemented guidelines that require doctors to screen for TB before prescribing biologics to patients. The 2020 guidelines advise screening questions, performance of a chest X-ray (CXR) and an interferon-γ release assay (IGRA). Current studies show that CXR has a sensitivity of 15% when diagnosing latent TB. While there is no gold standard for diagnosing latent TB, the IGRA is a commonly used test and is shown to be four times more effective than the tuberculin skin test. This study questions the diagnostic value of CXR in the screening of TB in asymptomatic patients, and whether it should be removed from the guidelines for such patients. A retrospective audit of dermatological patients in our trust was done over a 24-month period (January 2020–January 2022). Patients selected for the audit were those diagnosed with psoriasis or hidradenitis suppurativa and started on biologics during this 24-month period. Patients were assessed on the following: patient history, CXR results, IGRA results and screening outcomes. The data were quantitatively analysed to uncover the necessity of performing a CXR on patients starting biologics. Between January 2020 and January 2022, 77 patients were scheduled for prebiologic TB screening; CXRs were performed in 74 patients (96%), while 72 (94%) of patients had IGRA tests. During this period, three patients (4%) were diagnosed with latent TB based on positive IGRA results and normal CXR findings. They were subsequently treated for latent TB infection prior to biologic therapy. None of the patients with negative IGRA results had positive CXR findings for TB. This finding suggests that CXR is unnecessary at the initial stage of prebiologic TB screening for asymptomatic patients. IGRA can detect both latent and active TB, while CXR is recommended for the diagnosis of active TB. Mandating CXR comes at a cost to the National Health Service and subjects patients to unnecessary radiation exposure. We propose that CXR be done only for patients who are either symptomatic for TB or have a positive IGRA result.

Interferon-γ release assay and mantoux response in infants with tuberculous meningitis in low and intermediate burden countries

AimUntil now, the performance of interferon-γ release assay (IGRA) and Mantoux tests remains unclear in infant tuberculous meningitis (TBM). Therefore, a systematic review is performed to evaluate the sensitivity of IGRA and Mantoux tests for the diagnosis of infant TBM in low and intermediate tuberculosis (TB) burden countries, while following PRISMA.MethodsSeveral databases, including PubMed, EBSCO, Embase, Scopus, Web of Science, ClinicalTrials.gov, and Cochrane Central Register of Controlled Trials, were searched. Articles describing the results of IGRA or Mantoux tests among infant TBM were included for analysis. Data, such as age, sex, Mantoux test or IGRA, and cerebrospinal fluid (CSF) microbiological examinations (such as acid-fast bacilli (AFB) smear, TB PCR, and TB culture), were extracted from each study.ResultsA total of 31 articles were enrolled for further analysis, including 48 cases. The mean age was 9.4 ± 5.8 months and boys accounted for 57.1% of infants (24/42). Mantoux test was positive in 57.4% (27/47) of tested infants and IGRA was positive in 77.8% (7/9) of infants. In addition, among the infants with confirmed TB, 18 (52.9%, 18/34) of them have positive Mantoux responses and 7 (20.0%, 7/35) have positive IGRA results.ConclusionsIn low or intermediate TB burden countries, the Mantoux test has a poor performance for diagnosing TBM among infants, and IGRAs appear to have a moderate sensitivity for the diagnosis of infant TBM.

Performance of two interferon-gamma release assays for tuberculosis infection screening in Kawasaki children before immunosuppressive therapy.

We aimed to compare QuantiFERON-TB Gold In-Tube (QFT-GIT) and X.DOT-TB for screening latent tuberculosis infection (LTBI) in kawasaki patients, and to identify the risk factors associated with indeterminate IGRA results. We conducted a retrospective study on children with KD, who were screened for mycobacterium tuberculosis (Mtb) infection by either ELISA-based QFT-GIT or ELISPOT-based X.DOT-TB tests, admitted in Department of Cardiology, Beijing Children's Hospital from July 2019 to April 2022. A total of 1327 cases were included. Among them, 932 cases were tested by QFT-GIT and 395 cases by X.DOT-TB. The positive rate of children was 0.1% and 0.2%, and the indeterminate rate was 68.2% and 6.1% for QFT-GIT and X.DOT-TB, respectively. Patients with hypoproteinemia had a higher risk of indeterminate X.DOT-TB result. Female, critical ill, shock or hypoproteinemia presented statistically significant associations with an increased risk of indeterminate QFT-GIT result. High-dose of IVIG inhibited the release of IFN-γ by more than 90%, which might account for the high indeterminate incidence. It is recommended to perform X.DOT-TB rather than QFT-GIT to screen LTBI in patients with high level of the mitogen that can inhibit IFN-γ release. For KD children with positive IGRA results, it has a higher risk of activation TB infection when treated with immunosuppressive therapy in the future. Children with KD aged <5 years old had higher frequency of indeterminate IGRA results.

BCG-Vaccinated Children with Contact to Tuberculosis Patients Show Delayed Conversion of Mycobacterium tuberculosis-Specific IFN-γ Release.

Mycobacterium (M.) bovis BCG vaccination is recommended for healthy babies after birth in several countries with a high prevalence of tuberculosis, including Ghana. Previous studies showed that BCG vaccination prevents individuals from developing severe clinical manifestations of tuberculosis, but BCG vaccination effects on the induction of IFN-γ after M. tuberculosis infection have hardly been investigated. Here, we performed IFN-γ-based T-cell assays (i.e., IFN-γ Release Assay, IGRA; T-cell activation and maturation marker assay, TAM-TB) in children who had contact with index tuberculosis patients (contacts). These contacts were classified as either being BCG vaccinated at birth (n = 77) or non-BCG-vaccinated (n = 17) and were followed up at three timepoints for a period of one year to determine immune conversion after M. tuberculosis exposure and potential infection. At baseline and month 3, BCG-vaccinated contacts had significantly lower IFN-γ levels after stimulation with M. tuberculosis-specific proteins as compared to non-BCG-vaccinated contacts. This resulted in decreased proportions of positive IGRA results (BCG-vaccinated: 60% at baseline, 57% at month 3; non-BCG-vaccinated: 77% and 88%, respectively) at month 3. However, until month 12, immune conversion in BCG-vaccinated contacts led to balanced proportions in IGRA responders and IFN-γ expression between the study groups. TAM-TB assay analyses confirmed higher proportions of IFN-γ-positive T-cells in non-BCG-vaccinated contacts. Low proportions of CD38-positive M. tuberculosis-specific T-cells were only detected in non-BCG-vaccinated contacts at baseline. These results suggest that BCG vaccination causes delayed immune conversion as well as differences in the phenotype of M. tuberculosis-specific T-cells in BCG-vaccinated contacts of tuberculosis patients. These differences are immune biomarker candidates for protection against the development of severe clinical tuberculosis manifestations.

Disease phenotypic and geospatial features vary across genetic lineages for Tuberculosis within Arkansas, 2010-2020.

Tuberculosis (TB) elimination in the United States remains elusive, and community-specific, localized intervention strategies may be necessary to meet elimination goals. A better understanding of the genotypic diversity of Mtb, the population subgroups affected by different TB strains, and differences in disease presentation associated with these strains can aid in identifying risk groups and designing tailored interventions. We analyze TB incidence and genotype data from all Arkansas counties over an 11-year time span from 2010 through 2020. We use statistical methods and geographic information systems (GIS) to identify demographic and disease phenotypic characteristics that are associated with different Mtb genetic lineages in the study area. We found the following variables to be significantly associated with genetic lineage (p<0.05): patient county, patient birth country, patient ethnicity, race, IGRA result, disease site, chest X-ray result, whether or not a case was identified as part of a cluster, patient age, occupation risk, and date arrived in the US. Different Mtb lineages affect different subpopulations in Arkansas. Lineage 4 (EuroAmerican) and Lineage 2 (East Asian) are most prevalent, although the spatial distributions differ substantially, and lineage 2 (East Asian) is more frequently associated with case clusters. The Marshallese remain a particularly high-risk group for TB in Arkansas.

Optimising diagnosis and treatment of tuberculosis infection in community and primary care settings in two urban provinces of Viet Nam: a cohort study

ObjectivesTo end tuberculosis (TB), the vast reservoir of 1.7–2.3 billion TB infections (TBIs) must be addressed, but achieving global TB preventive therapy (TPT) targets seems unlikely. This study assessed the...

PREVALENCE OF LATENT TUBERCULOSIS INFECTION AMONG MEDICAL WORKERS

The analysis of the results of immunological tests (skin test with tuberculosis recombinant allergen in standard dilution, hereinafter referred to as the test with ATP) and laboratory immunological test IGRA, delivered in 2019-2022 to employees of medical organizations of the Moscow Department of Health, working in four administrative districts of Moscow (Central, Western, South-Western, Troitsk and Novomoskovsk, next – CAD, WAD, SWAD/T&amp;NAD). Among the average annual number of employees over 5 years – 43,452 people, with medical examination and exclusion of tuberculosis, the prevalence of persons with latent tuberculosis infection (LTI) was 2.6, 6.1 and 1.8%, in the CAD, WAD and SWAD/T&amp;NAD, respectively, or 3.4% in general to these districts. At the same time, the average annual frequency of detection of cases of LTI («first detected LTI») was 0.6, 1.3 and 0.6% in these districts, respectively, and 0.75% in all districts as a whole. 95.4% of the employees were assigned a course of preventive therapy (PT), 45.8% of which the course was started. Among the latter, 85.0% successfully completed the course, 14.1% – the course was interrupted by the patient, and 0.9% – canceled by the doctor due to adverse events. The main PT regimen used (78.4%) included 3 months of taking a combination of isoniazid and pyrazinamide (INN: isoniazid 150 mg + pyrazinamide 500 mg), which showed a low proportion of adverse events – 3.1%. The identification of workers of medical organizations of LTI allows to determine a group high risk for tuberculosis and to allocate a group of persons for preventive therapy

1438. Latent tuberculosis infection (LTBI) in hematopoietic stem cell transplantation (HSCT) recipients: a retrospective Italian cohort study in Tor Vergata University Hospital, Rome.

Abstract Background Patients undergoing haematopoietic stem cell transplantation (HSCT) have severe and prolonged immunodeficiency and the incidence of tuberculosis (TB) disease in those patients is 10 to 40 times higher than the general population Methods This retrospective study performed at Tor Vergata University Hospital in Rome (Italy) included all adult patients who underwent a HSCT in the Hematologic Transplant Unit from January 2015 to December 2019. Data on TB screening, performed through interferon-γ release assay (IGRA), were collected; patients were observed for TB reactivation in a follow up period of at least 3 years Results 323 HSCT recipients were enrolled in this study. Patients’ characteristics are summarized in table 1. 63 patients (19.5%) were not screened for TB, of which 6.3% were born overseas. 260 HSCT recipients (80.5%) were screened: 228 patients (87.7%) had a negative IGRA result, 21 (8.1%) tested positive, and 11 (4.2%) had an indeterminate result. 98.5% were screened before the HSCT. Of the 21 patients with a positive pre-HSCT IGRA test, 14 (66.7%) were males and significantly (p&amp;lt; 0.001) older (median age 60 [IQR] 58-65 years) than those with negative or indeterminate results. Almost all patients (95.2%) were Italian. Patients with a positive IGRA showed a higher monocyte count compared to the other groups (p=0.044), while those with indeterminate IGRA showed a tendence to lower lymphocyte absolute counts, compared to the other groups (p=0.060) (Table 2). All the 21 patients with a pre-HSCT positive IGRA test were radiologically and clinically screened for active TB and, once it was ruled out, treated for latent TB (LTBI) with isoniazid (INH) for 6 months. No events of toxicity or treatment interruption were reported. None of the patients was treated with rifampin. None of the 21 patients with pre-HSCT positive IGRA test developed active TB during the follow up period. Table 1.Characteristics of the study population, overall and divided according to IGRA testingTable 2.Characteristics of the IGRA tested patients, overall and divided by IGRA test results Conclusion To our knowledge, this is the first Italian study on the prevalence of LTBI in patients undergoing HSCT. 8.1% of the 260 patients screened with an IGRA tested positive. The great majority (95.2%) of LTBI patients were Italian and significantly older than IGRA-negative patients. All LTBI HSCT patients received INH treatment and no drug toxicity, nor TB reactivation was observed during the follow-up period Disclosures All Authors: No reported disclosures.

Interferon-γ release assay screening in biologics: safe and reliable, but not perfect.

Systemic biologic agents can increase the risk of re-activation of latent tuberculosis (TB). Prior to initiation, screening for latent TB using an interferon-γ release assay (IGRA) is recommended. There is concern that false-negative IGRAs may be more likely in this context. This retrospective analysis of IGRAs, specifically T-SPOT.TB, results and outcomes of patients already on or due to start biologics identifies the rate of TB re-activation in a low TB incidence setting. Additionally, we estimate the negative predictive value (NPV) of IGRAs in this population. Patients on biologics were more likely to have a negative IGRA result than patients not on biologics. There was no statistically significant change in conversion or reversion rates between groups. Of 9263 patients on biologics, 19 developed active TB after starting biologics at an incidence rate of 55.1 per 100 000 patient-years. This occurred despite screening in half of the 16 patients for whom we were able to review medical records. Most drugs implicated were known to be high risk, although rituximab and natalizumab were being taken by five patients and one patient, respectively. The T-SPOT.TB NPV was 99.20% and dropped only slightly to 99.17% when we simulated an approach where all borderline IGRA results were regarded as being negative. Negative IGRA results confer a low risk of subsequent active TB in patients on biologics in a low TB incidence setting. However, continued awareness is needed given that a number of active TB cases will have had a prior negative result.

CD69 flow cytometry to complement interferon-γ release assay for active tuberculosis.

The interferon-γ (IFN-γ) release assay (IGRA) is widely used to diagnose tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb). However, indeterminate IGRA results due to "high Nil" or "low PHA" responses limit its clinical utility. We developed a novel assay using CD69 flow cytometry (FC) to complement IGRA. CD69 FC measures the surface CD69 expression on T cells prior to centrifugation to harvest the plasma for IGRA. T cell responses against Mtb antigen 1 (Ag1) or Ag2 were measured using three-color FC (CD3, CD4, and CD69) in TB (n=140) and non-TB groups (n=117). The cutoff values of Δ%CD69bright cells (stimulated minus unstimulated) for CD4+ and CD4- T cells were established based on healthy individuals (n=63). The assay performances of CD69 FC and IGRA were compared. In subjects with determinate IGRA results ("positive" or "negative"; n=216), the diagnostic accuracies of CD69 FC (90.3%) and IGRA (87.0%) were not significantly different (p=0.31). For indeterminate IGRA results (n=40), CD69 FC attained a diagnostic accuracy of 92.5%. The CD4+ /CD4- ratio within CD69bright T cells measured by CD69 FC was significantly higher (p < 0.05) in the active TB group (6.39 ± 132.05; n=72) than in other CD69 FC-positive subjects (2.84 ± 15.36; n=63) (p < 0.05), whereas CD8 responses expected by IGRA (difference of IFN-γ levels between Mtb Ag tubes) did not differ significantly (0.00 ± 9.18 and 0.00 ± 4.25, respectively, IU/ml; p=0.58). We demonstrated the potential of CD69 FC as a simple, rapid assay for clarifying indeterminate IGRA results and identifying active TB. With further improvements, CD69 FC may complement the IGRA to enhance TB risk stratification in the routine diagnostic workup.

Significant difference in Th1/Th2 paradigm induced by tuberculosis-specific antigens between IGRA-positive and IGRA-negative patients.

False negative interferon-γ release assay (IGRA) results constitute the major dilemma for the diagnosis of tuberculosis (TB) infections. Herein, we conducted a cohort study to compare the host immunological response to TB-specific antigens between active TB patients with positive and negative IGRA results and control groups. A total of 274 laboratory-confirmed TB patients were included in our analysis, consisting of 221 were IGRA positive and 53 were IGRA negative. Patients with the elderly were identified as an independent risk factor for negative IGRA results. In addition, the elevated level of IL-4 and the decreased levels of IFN-γ, IL-2, IL-6, IL-1β, and IL-12 in IGRA negative TB relative to IGRA positive TB group, demonstrating a significant difference in Th1/Th2 paradigm between two groups. The IFN-γ&IL-2 based assay could correctly identify 247 out of 307 MTB-infected individuals [271 TB patients and 36 individuals with latent TB infection (LTBI)], demonstrating a sensitivity of 80.5%. Then the IFN-γ and IL-4 were applied to distinguish healthy control and IGRA-negative group. When using the stepwise algorithm, the sensitivity for detecting Mycobacterium tuberculosis (MTB) infections was significantly increased from 80.5% to 89.6%. Additionally, patients with negative IGRA results had a conversion to culture-negative status longer than those with positive IGRA results. In conclusion, a stepwise algorithm outperforms IGRA assays to accurately identify MTB infections by the combination IFN-γ, IL-2, and IL-4. Further study is needed to evaluate the accuracy of our diagnostic algorithm in the LTBI population.

Correlation between tuberculosis-specific interferon-γ release assay and intrathoracic calcification: A cross-sectional study.

BackgroundAlthough persistent tuberculosis (TB) infection is known to cause calcification in the lungs, the relationship between intrathoracic calcification and the results of the interferon-γ release assay (IGRA) has not been fully elucidated. This study aimed to assess the association between intrathoracic calcification and IGRA results.MethodsWe retrospectively included consecutive patients who concurrently underwent chest X-ray, chest computed tomography (CT), and an IGRA. Patients with a current diagnosis of active TB or treatment history of active TB or latent tuberculosis infection (LTBI) were excluded. The association between calcification according to the chest X-ray or CT and IGRA results were analyzed using binomial logistic regression.ResultsThis study included 574 patients, and 38 (7%) patients had a positive IGRA result. Patients with a positive result were significantly older and had a higher proportion of comorbidities, and history of tuberculosis exposure compared to those with a negative result. Calcification of the lung field and mediastinal lymph nodes according to chest CT was more frequently observed in patients with a positive IGRA result, whereas no significant difference was observed concerning the proportion of lung field calcification on chest X-ray between patients with positive and negative IGRA results. In multivariate analysis, calcification of mediastinal lymph nodes alone (adjusted odds ratio [OR] = 3.82, 95% confidence interval [CI] = 1.76–8.26) and the combination of lung field and mediastinal lymph node calcification (adjusted OR = 4.12, 95% CI = 1.51–11.76) on chest CT was independently associated with positive IGRA results.ConclusionsThe finding of mediastinal lymph node calcification, with or without lung field calcification, on chest CT was associated with positive IGRA results independent of TB exposure history. Previous TB infection including eliminated TB infection and LTBI can be suspected when calcified lymph nodes in are observed the mediastinum on chest CT.

Suspicion of bovine tuberculosis in sheep in the Małopolskie Voivodeship (southern Poland).

Bovine tuberculosis (BTB) in sheep (Ovis aries) is caused by Mycobacterium bovis and Mycobacterium caprae. Even though sheep have been considered less sensitive to BTB than other ruminants, they have been subject to increasing numbers of tuberculosis cases and it has been suggested that they may act as a disease reservoir in some regions. Aim of the study: Following a report of tuberculous-like gross lesions (repeated cases of purulent or caseous lymphadenitis and a single case of serosal tubercles on the peritoneum) from veterinarians working in a slaughterhouse in the Małopolskie Voivodeship, southern Poland, the aim of this study was to conduct ante-mortem BTB diagnostics in three flocks with suspected BTB. The animals for testing were selected randomly from the flocks; a blood sample for interferon-γ release assay (IGRA) and a single tuberculin skin test (TST) was performed on each sheep. All TST results were negative. The IGRA result was positive in two ewes from the same flock (four and five years of age); these two sheep were tested microbiologically using Stonebrink and Löwenstein-Jensen media. No gross lesions suggesting BTB were observed, and the culture results were negative. Based on the positive IGRA results, together with its high specificity in sheep, and the potential risk to humans posed by consuming local unpasteurized dairy products, we recommend introducing serological BTB screening in sheep from this area, and subjecting the positive results to confirmation by culture.