Positive QuantiFERON-TB Gold Test Research Articles

Concurrent syphilis, gonorrhea, and monkeypox: A case report.

Documented cases of monkeypox virus outside of Africa are rare, but as of August 22, 2022, the CDC was tracking 18,101 cases in the United States. Monkeypox rash can easily mimic other sexually transmitted infections, which may occur concurrently. This case report describes a 36-year old Caucasian man who has sex with men. The patient came in for a routine history and physical examination and disclosed a perianal rash. The patient had a medical history significant for undertreated HIV, ankylosing spondylitis, and homelessness. On examination, he had multiple perianal deep-seated ulcers that were swabbed for monkeypox and herpes simplex virus 1 and 2. Samples were also collected for syphilis, chlamydia, and gonorrhea. The swabs were positive for monkeypox and pharyngeal gonorrhea. At subsequent blood draw, he was found to have elevated titers for syphilis and a positive QuantiFERON-TB gold test. In summary, this case is a clear example of an individual with concurrent monkeypox virus and other sexually and nonsexually transmitted infections, highlighting the importance of careful identification of risk factors and testing for monkeypox virus even when the clinical presentation may depict a common sexually transmitted infection, such as the herpes simplex virus.

Association between latent tuberculosis and ischemic heart disease: a hospital-based cross-sectional study from Saudi Arabia.

Introductionatherosclerosis could be a sequela of long-term activation of cell-mediated immunity as the case of latent tuberculosis infection. Atherosclerosis is the main pathological event in ischemic heart disease. The present study aimed to assess the prevalence of Latent tuberculosis infection (LTBI) among patients with ischemic heart disease (IHD) and to detect the association between both diseases.Methodsthis cross-sectional study included 98 patients with a history of previously diagnosed ischemic heart disease who did a multi-detector computed tomography coronary angiogram (MDCTCA). Detailed clinical examination and investigations as chest X-ray and sputum examination were done for those with positive QuantiFERON-TB Gold test (QFT) to exclude active tuberculosis (TB). Participants having positive QFT results but with no evidence of active TB were considered as LTBI positive.Resultsthe prevalence of LTBI in patients with IHD was 19.3% as only nineteen of the ninety-eight patients were diagnosed with latent tuberculosis infection using the QuantiFERON serum test. Eighty-four percent (84.2%) of patients with LTBI had coronary artery atherosclerosis (CAA) compared to only 55.6% in patients without LTBI with a statistically significant difference. In multivariable analysis, Diabetes Mellitus (DM) (AOR 0.179, 95% C.I.: 0.03-0.967), and LTBI (AOR 1.024, 95% C.I.: 1.002-1.736) were significantly associated with coronary artery atherosclerosis (p=0.0001, and p= 0.003 respectively).Conclusionthe prevalence of latent tuberculosis infection among patients with ischemic heart diseases is high. Among different factors that are already well known to precipitate ischemic heart disease, latent tuberculosis should be considered.

SUN-166 Primary Adrenal Insufficiency Caused by Underlying Tuberculosis

IntroductionPrimary adrenal insufficiency (AI) is a rare endocrine disorder affecting 1 in 100,000 people. Primary AI is a gradual destruction of the adrenal cortex. Etiology includes autoimmune, tuberculosis, histoplasmosis, blastomycosis, adrenal metastases, primary adrenal tumors, and opportunistic infections of HIV. Since aggressive treatment of TB, the incidence of TB adrenalitis has significantly declined, now accounting for 20% of reported cases where as autoimmune causes of AI account for 70%. Most common symptoms are non-specific, and diagnosis is often delayed, with patient initially presenting with a life-threatening adrenal crisis.CasePatient is an incarcerated 65 y/o African American male with PMHx of hypothyroidism who was admitted to the hospital for AMS after being found unresponsive in his prison cell. On admission, patient was febrile, hypotensive and tachycardic. He looked disheveled, confused, and lethargic. Other exam findings were negative.Lab results revealed WBC 11.7/μL, serum sodium 116 mmol/L, serum potassium 5.2 mmol/L, serum glucose 68 mg/dL, serum osmolality 237mOsm/kg, TSH 26.3mIU/L, and random cortisol 1.6ug/dL. ACTH stimulation test revealed pre-challenge cortisol levels 5.1ug/dL, 30-minute 4.9ug/dL and 60-minute 4.5ug/dL. ACTH 1271 pg/mL (normal range 7.2-63.3pg/mL). A normal response is a stimulated cortisol level > 18ug/dl. Chest x-ray revealed left lower lobe pneumonia.Clinical signs/symptoms and labs were consistent with primary AI. Adrenal crisis was most likely precipitated by underlying pneumonia. Workup was negative for 21-Hydrolase Antibodies, HIV, CMV, and histoplasmosis. However, QuantiFERON-TB Gold Test was positive. Abdominal CT revealed bilateral enlarged non-enhancing adrenal nodules with coarse calcifications. Biopsy of right adrenal gland revealed necrotizing caseating granulomatous inflammation. Biopsy was negative for isolated aerobic, anerobic, fungal organisms, AFB, and mycobacterium PCR.Due to current findings and high suspicion of TB adrenalitis, patient is currently being treated as culture-negative tuberculosis along with PO hydrocortisone for underlying AI.DiscussionAdrenal tuberculosis is a rare cause of primary adrenal insufficiency in developed countries. There should be high suspicion for AI when a patient presents with hypotension, hyponatremia, hyperkalemia and/or hypoglycemia. In this case, although patient did not have a positive AFB culture, he did have a positive QuantiFERON-TB Gold Test along with consistent findings on CT and biopsy. Thus, case was concluded to have high suspicion of primary AI secondary to underlying untreated tuberculosis. Prompt treatment with antituberculosis medication, appropriate steroid therapy, along with monitoring of adrenal function, underlying adrenal insufficiency may be reversible if detected in early stages and decrease mortality.

QuantiFERON-TB Gold Test Conversion Is Associated with Active Tuberculosis Development in Inflammatory Bowel Disease Patients Treated with Biological Agents: An Experience of a Medical Center in Taiwan.

Taiwan has a lower prevalence of inflammatory bowel disease (IBD) and a higher prevalence of tuberculosis (TB) infection than Western countries. The aim of this study was to investigate the prevalence of latent TB (LTB) and active TB infection in IBD patients treated with biological agents. From January 2000 to September 2018, we retrospectively collected data from IBD patients treated with biological agents at a tertiary referral center. Patients underwent a QuantiFERON-TB Gold test (QFT) to screen for TB infection before and after biological treatment courses. The diagnostic age, sex, body mass index, hepatitis B virus infection, biochemistry profile, treatment regimens, and the results of the QFT were analyzed. Overall, 130 IBD patients who received biological treatment were enrolled. The results of the QFT before biological treatment were determined in 120 patients (92%); of these, 10 were positive (8%), 110 were negative (85%), and 10 were indeterminate (9%). Six patients demonstrated seroconversion after biological treatment, as determined by the QFT. Three patients (2.4%) developed active pulmonary TB after biological treatment. In subgroup analysis, the positive QFT patients had a trend of lower baseline serum C-reactive protein and erythrocyte sedimentation rate levels than the negative QFT group. The present study demonstrates that the prevalence of LTB before and after biological treatment is higher in Taiwan than in most Western countries and similar to other Asian countries. Therefore, screening and monitoring of TB infection are necessary for IBD patients before and during biological treatments in Taiwan.

Real life experience of a screening strategy for latent tuberculosis before treatment with biologicals in indian patients with rheumatic diseases

Objective: The objective of the study was to study the effectiveness of a recommended screening strategy for latent tuberculosis infection (LTBI) in patients with systemic inflammatory rheumatic diseases (SIRDs) treated with biological disease-modifying antirheumatic drugs (bDMARDs). Methods: The study included patients being considered for bDMARD treatment. Screening strategy included screening with “4S symptom complex (current cough, fever, weight loss, and night sweats) for TB,” augmented Mantoux test using ten tuberculin unit (TU) strength simultaneously with QuantiFERON®-TB Gold (QFTG) test. Those with a Mantoux test reading of ≥10 mm induration at 48–72 h and/or with a positive QFTG test, were given TB prophylaxis before initiating bDMARDs. They were followed and monitored for any features of tuberculosis flare. Results: A total of 730 patients (265 rheumatoid arthritis, 400 axial spondyloarthritis [axSpA], 34 psoriatic arthritis, and 31 others) were considered for bDMARDs. Two hundred and sixty-seven (36.6%) were positive for LTBI. They were treated either with isoniazid monotherapy for 6 months or with rifampicin + isoniazid for 4 months. bDMARDs were started 1 month after initiating chemoprophylaxis. Five (0.68%) patients developed active TB disease in the follow-up. In a total of 2930 “control” patients with the same diseases but never having taken bDMARDs, 18 (0.61%) developed active TB disease. The proportion of patients developing active TBI during the same period of follow-up did not differ between those who were and those who were not treated with bDMARDs. None of the study participants had “4S” symptoms. Conclusion: The strategy of clinical screening for active TBI with “4S complex,” standard chest radiograph, and an augmented Mantoux testing (10 TU purified protein derivative, [PPD]) simultaneously with QFTG test for the screening of LTBI, was successful in identifying active TBI in patients treated with bDMARDs.

Tuberculosis and other causes of uveitis in Indonesia.

PurposeThe purpose of this study is to assess the causes of uveitis in Indonesia and determine the importance of tuberculosis (TB) as a cause of uveitis.Patients and methodsProspective cohort study examining 146 consecutive new human immunodeficiency virus-negative patients with active uveitis between June 2014 and May 2015. We assessed the anatomic locations and specific causes of uveitis, as well as associations with infectious and non-infectious systemic diseases. We determined the prevalence of positive QuantiFERON Tb Gold test (QFT) results in Indonesian patients with uveitis and calculated the number of patients with active systemic TB.ResultsPosterior and panuveitis were the most common anatomic entities (38% each). Infections represented the most frequent cause of uveitis (33%); the most prevalent were toxoplasmosis (19%) and active systemic TB (8%). The majority of patients were QFT positive (61%). A specific diagnosis could not be established in 45% of the patients. At first presentation to the ophthalmologist, the majority of patients (66%) had a visual acuity of less than finger counting at 3 m and already exhibited various complications of uveitis. When classifying the QFT-positive patients with unexplained uveitis into a TB-related group, the percentage of 'TB-associated' uveitis cases increased from 8-48%. Highly elevated QFT levels were observed in patients with uveitis of unknown cause and no signs of active systemic TB.ConclusionsIn Indonesia, infectious uveitis was the most common type of uveitis and the leading causes consisted of toxoplasmosis and TB. The association observed between highly elevated QFT results and uveitis of otherwise unexplained origins indicates that a link exists between the latent TB infection and the development of uveitis.

Mycobacterium kansasii Infection in a Patient Receiving Biologic Therapy—Not All Reactive Interferon Gamma Release Assays Are Tuberculosis

Mycobacterium kansasii, a nontuberculous mycobacterium, can lead to lung disease similar to tuberculosis. Immunotherapeutic biologic agents predispose to infections with mycobacteria, including M kansasii. T-cell–mediated interferon gamma release assays like QuantiFERON-TB Gold Test (QFT) are widely used by clinicians for the diagnosis of infections with Mycobacterium tuberculosis; however, QFT may also show positive result with certain nontuberculous mycobacterial infections. We report a case of M kansasii pulmonary infection, with a positive QFT, in an immunocompromised patient receiving prednisone, leflunomide and tocilizumab, a humanized anti–interleukin-6 receptor monoclonal antibody. This case highlights the risk of mycobacterial infections with the use of various biologic agents and the need for caution when interpreting the results of interferon gamma release assays.

Enhanced Tuberculosis Infection Treatment Outcomes after Implementation of QuantiFERON®-Gold Testing.

BackgroundUse of the tuberculin skin test (TST) for diagnosis of latent tuberculosis infection (LTBI) among individuals who received the Bacille Calmette-Guérin (BCG) vaccine is complicated by its potential cross-reaction with TST antigens which may cause false-positive results and lead to patient and physician reluctance to initiate LTBI treatment. QuantiFERON®-TB Gold (QFT-G) lacks this cross-reaction. We sought to study the impact of implementing QFT-G testing in 2006 on LTBI treatment initiation and completion at NYC chest clinics.MethodsQFT-G results from 10/2006–12/2008 in NYC Department of Health and Mental Hygiene chest clinics were obtained from the electronic medical record system. The proportions of patients who initiated and completed treatment among patients tested with QFT-G were compared to those tested with TST from 10/2004–9/2006.ResultsAmong 36,167 patients tested with QFT-G, 2,300 (6%) tested positive, 33,327 (93%) tested negative, and 540 (1%) had an indeterminate result. Among those who had a positive QFT-G test and deemed eligible, 985 (80%) initiated LTBI treatment and 490 (40%) completed treatment. Historically, among patients tested with TST, 7,073 (19%) tested positive (p<0.0001 compared to QFT-G); 3,182 (79%) of those eligible initiated LTBI treatment and 1,210 (30%) completed treatment (p<0.0001 compared to QFT-G).ConclusionsQFT-G implementation increased the proportion of patients completing LTBI treatment. Additional studies are needed in more settings to determine whether using QFT-G leads to a sustained increase in treatment completion.

Differential Diagnosis of Crohn's Disease and Intestinal Tuberculosis in Patients with Spontaneous Small-Bowel Perforation

Background/Aims: Spontaneous small-bowel perforation caused by Crohn's disease (CD) or intestinal tuberculosis (ITB) is a rare disease entity. We investigated the clinical features and radiologic findings of patients with CD or ITB who presented with a spontaneous small-bowel perforation. Methods: Between January 2001 and December 2010, sixty-two patients underwent surgery due to a spontaneous small-bowel perforation, including 21 (33.9%) CD patients and 18 (29.0%) ITB patients. Clinical and radiologic features were compared between CD and ITB patients. Results: The mean age was significantly lower in CD patients than in ITB patients (p = 0.014). Diarrhea was more common in CD. By contrast, night sweating and a previous history of tuberculosis were more common in ITB. Only 27.8% of patients with ITB had a positive QuantiFERON-TB Gold test. CT findings such as bowel wall thickening of more than 10 mm, omental thickening, and intra-abdominal lymphadenopathy larger than 10 mm were more common among perforations caused by ITB. Mesenteric fat infiltration was a more frequent finding in CD than in ITB. Conclusions: Clinical symptoms and radiologic findings may aid in the differential diagnosis between CD and ITB in patients presenting with spontaneous small-bowel perforation.

P31 Assessing the effectiveness of tuberculosis (TB) screening in new entrant healthcare workers using different time cut-offs to define high risk individuals

Introduction and ObjectivesNICE (2011) and the Department of Health (2007) provide guidance for occupational health departments for TB clearance in healthcare workers. Previous work from the London Consortium of Occupational...

Diagnosis of intestinal tuberculosis using a monoclonal antibody toMycobacterium tuberculosis

To investigate the utility of immunohistochemical (IHC) staining with an antibody to Mycobacterium tuberculosis (M. tuberculosis) for the diagnosis of intestinal tuberculosis (TB). We retrospectively identified 10 patients (4 males and 6 females; mean age = 65.1 ± 13.6 years) with intestinal TB. Clinical characteristics, including age, gender, underlying disease, and symptoms were obtained. Chest radiograph and laboratory tests, including sputum Ziehl-Neelsen (ZN) staining, M. tuberculosis culture, and sputum polymerase chain reaction (PCR) for tubercle bacilli DNA, as well as Tuberculin skin test (TST) and QuantiFERON-TB gold test (QFT), were examined. Colonoscopic records recorded on the basis of Sato's classification were also reviewed, in addition to data from intestinal biopsies examined for histopathological findings, including hematoxylin and eosin staining, and ZN staining, as well as M. tuberculosis culture, and PCR for tubercle bacilli DNA. For the present study, archived formalin-fixed paraffin-embedded (FFPE) intestinal tissue samples were immunohistochemically stained using a commercially available species-specific monoclonal antibody to the 38-kDa antigen of the M. tuberculosis complex. These sections were also stained with the pan-macrophage marker CD68 antibody. From the clinical data, we found that no patients were immunocompromised, and that the main symptoms were diarrhea and weight loss. Three patients displayed active pulmonary TB, six patients (60%) had a positive TST, and 4 patients (40%) had a positive QFT. Colonoscopic findings revealed that all patients had type 1 findings (linear ulcers in a circumferential arrangement or linear ulcers arranged circumferentially with mucosa showing multiple nodules), all of which were located in the right hemicolon and/or terminal ileum. Seven patients (70%) had concomitant healed lesions in the ileocecal area. No acid-fast bacilli were detected with ZN staining of the intestinal tissue samples, and both M. tuberculosis culture and PCR for tubercle bacilli DNA were negative in all samples. The histopathological data revealed that tuberculous granulomas were present in 4 cases (40%). IHC staining in archived FFPE samples with anti-M. tuberculosis monoclonal antibody revealed positive findings in 4 patients (40%); the same patients in which granulomas were detected by hematoxylin and eosin staining. M. tuberculosis antigens were found to be mostly intracellular, granular in pattern, and primarily located in the CD68(+) macrophages of the granulomas. IHC staining with a monoclonal antibody to M. tuberculosis may be an efficient and simple diagnostic tool in addition to classic examination methods for the diagnosis of intestinal TB.

Comparison of QuantiFERON-TB Gold test and tuberculin skin test for the identification of latentMycobacterium tuberculosisinfection in lupus patients

The tuberculin skin test (TST) has low sensitivity for the diagnosis of tuberculosis (TB). QuantiFERON-TB Gold (QFT-G) is an IFN-gamma-release assay that measures the release of interferon-gamma after stimulation in vitro by Mycobacterium tuberculosis antigens using ELISA. The main advantage of this assay compared with TST is the lack of cross-reaction with Bacillus Calmette-Guérin (BCG) as well as most of non-tuberculous mycobacteria. The aim of our study is to compare QFT-G with TST for the detection of latent tuberculosis infection (LTBI) among patients with systemic lupus erythematosus (SLE). Seventy-eight patients with SLE and 49 healthy subjects (HCs) participated in the study. All patients and controls were interviewed for a history of TB then BCG vaccinations were recorded and chest X-rays were examined for a sign of TB infection. QTF-G and TST were performed on both patients and controls. QTF-G results were recorded as positive, negative or indeterminate. A positive TST for SLE was defined as ≥5 mm. Seventy-six SLE patients (97.4%) had been BCG vaccinated. Similar to the HC (28.5%), 19 of 78 (24.3%) SLE patients had positive QTF-G. Two patients had an indeterminate result. The agreement between QTF-G and TST was 49/76 (64.4%) (κ = 0.33). There were fewer positive QFT-G test results than positive TST results (24.3% vs. 50%; p < 0.01). Twenty-two (28.9%) patients were TST(+)/QTF-G(-) while only 3(3.9%) patients were TST(-)/QTF-G(+). When the positive TST was defined as ≥10 mm indurations, which is the cut-off in screening for LTBI in Turkey, the agreement between two tests increased up to 58/76 (76.3%) with a κ value of 0.47. The mean TST measurements was higher in QTF-G positive patients (13.4 ± 8.8 mm) than the QTF-G negative patients (4 ± 5.3 mm) (p < 0.001). In a TB-endemic and BCG vaccinated population, the QuantiFERON-TB Gold assay seemed to be a more accurate test for the detection of LTBI in SLE patients. Although 5 mm is usually accepted to be the standard cut-off for TST in immunocompromised patients such as SLE, the level of agreement between QTF-G and TST was better with a 10 mm cut-off in our population.

Clinical experience of QuantiFERON®-TB Gold testing in patients with psoriasis treated with tumour necrosis factor blockers in Taiwan

In Taiwan, an intermediate tuberculosis burden country, around 9·3% of patients with rheumatoid arthritis treated with adalimumab develop tuberculosis despite prescreening with the tuberculin skin test. Within the Asia-Pacific region, the tuberculosis risk in patients with psoriasis who use tumour necrosis factor (TNF) blockers is unknown. This study reports the use of QuantiFERON(®) -TB Gold (QFT-G) (Cellestis, Melbourne, Vic., Australia) as a screening method for latent tuberculosis infection (LTBI) in patients with psoriasis. This retrospective review evaluated 216 patients with psoriasis in whom TNF blockers were considered between 2004 and 2009 in a tertiary referral hospital in Taiwan. Beginning in 2007, QFT-G was performed on all patients who were candidates for TNF blockers. Seventeen patients who used TNF blockers for less than 4 weeks were excluded. Of the 147 assessed patients receiving TNF blockers, 110 (75%) underwent QFT-G tests. A total of 126 (86%) patients used etanercept and 40 (27%) patients used adalimumab. Nineteen patients switched between both. Overall, patients had a median of 24 weeks (range 4-307) exposure to TNF blockers. Twelve patients (11%) who were treated with TNF blockers and eight (15%) without TNF blockers had positive QFT-G results. Of all TNF blocker users, only one patient (0·68%) developed tuberculosis. QFT-G can be used to screen for LTBI in a tuberculosis endemic area where bacille Calmette-Guérin vaccination coverage is high. Isoniazid prophylaxis is recommended for those who have positive QFT-G test results.

Prospective evaluation of the clinical utility of interferon-γ assay in the differential diagnosis of intestinal tuberculosis and Crohnʼs disease

Distinguishing intestinal tuberculosis (ITB) from Crohn's disease (CD) is challenging. This study prospectively evaluated the clinical utility of the QuantiFERON-TB gold test (QFT) in the differential diagnosis of ITB and CD, and compared it with the clinical utility of the tuberculin skin test (TST). Patients with suspected ITB or CD on colonoscopic findings were enrolled from 13 hospitals in Korea between June 2007 and November 2008. A QFT and TST were performed. When the initial diagnosis was not confirmed, 2-3 months of empiric antituberculous therapy was administered. In all, 128 patients were analyzed; 64 patients had ITB and 64 patients had CD. The median age of patients with ITB was greater than the patients with CD (47 years versus 31 years, P < 0.001). The positive rate for the QFT and TST (≥10 mm) in patients with ITB was significantly higher than patients with CD (67% versus 9% and 69% versus 16%, respectively; P < 0.001). The QFT and TST had good agreement (κ = 0.724, P < 0.001). The diagnostic validity of QFT in ITB had a 67% sensitivity, 90% specificity, 87% positive predictive value, and 73% negative predictive value. There was no difference in these parameters between the QFT and TST. The likelihood ratio for a positive QFT was higher than a positive TST in the diagnosis of ITB (7.1 and 4.4, respectively). The QFT is a limited but useful diagnostic aid in combination with the TST in the diagnosis of ITB.

Presumed Tuberculosis-induced Retinal Vasculitis, Diagnosed with Positron Emission Tomography (18F-FDG-PET/CT), Aspiration Biopsy, and Culture

Purpose: The diagnosis of tuberculosis as an etiological factor in patients with uveitis is difficult because of lack of specific diagnostic tests. The authors report 2 cases of occlusive retinal vasculitis, in which 18F-FDG-PET/CT was helpful for the diagnosis of tuberculosis as a presumptive cause of intraocular inflammation.Methods: In 2 patients with severe occlusive retinal vasculitis and positive QuantiFERON TB-Gold test, 18F-FDG-PET/CT, transbronchial needle-aspiration biopsy, and microbiological investigation were performed.Results: 18F-FDG-PET/CT showed increased fluorodeoxyglucose uptake in some mediastinal and hilar lymph nodes. After needle-aspiration biopsy of PET-positive lymph nodes, M. tuberculosis was recovered in culture in both cases. Remission of uveitis was achieved only after a combination therapy with 3 anti-tubercular agents and systemic steroids.Conclusion: The authors favor the use of 18F-FDG-PET/CT in patients with sight-threatening intraocular inflammation and positive interferon-gamma release assay. Anti-tubercular therapy, together with anti-inflammatory treatment, may lead to a remission in such patients.

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

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. The interferon-gamma 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. 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). 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.

Discordant QuantiFERON-TB Gold Test Results Among US Healthcare Workers With Increased Risk of Latent Tuberculosis Infection: A Problem or Solution?

In late 2006, our hospital implemented use of the QuantiFERON-TB Gold (QFT-G) assay, a whole-blood interferon-gamma release assay, for detection of tuberculosis infection. All newly hired healthcare workers (HCWs) with positive Mantoux tuberculin skin test (TST) results were routinely tested with the QFT-G assay, to take advantage of its higher specificity. We then undertook a quality assurance review to evaluate the QFT-G test results in HCWs with multiple risk factors for latent tuberculosis infection (LTBI). The clinical records for TST-positive HCWs tested with the QFT-G assay were reviewed. HCWs with 2 or more risk factors commonly associated with LTBI were classified as "increased risk" (IR). IR HCWs who had negative QFT-G test results underwent repeat QFT-G testing and were offered testing with a different interferon-gamma release assay (T-SPOT.TB) and with extended T cell stimulation assays. Of 143 TST-positive HCWs tested with the QFT-G assay, 26 (18%) had positive results, 115 (81%) had negative results, and 2 (1%) had indeterminate results. Of 82 IR HCWs, 23 (28%) had positive QFT-G test results, and 57 (70%) had negative results. Of the 57 IR HCWs with negative results, 43 underwent repeat QFT-G testing: 41 had negative results again, and 2 had positive results. These 43 HCWs were also offered additional testing with the T-SPOT.TB diagnostic, and 36 consented: 31/36 tested negative, and 5/36 tested positive. Extended assays using the antigens ESAT-6 and CFP-10 confirmed the positive results detected by the overnight assays and yielded positive results for an additional 7/36 (19%) of individuals; strikingly, all 36 HCWs had strongly positive test results with assays using purified protein derivative. The extreme discordance between the results of our clinical diagnostic algorithm and the results of QFT-G testing raises concern about the sensitivity of the QFT-G assay for detection of LTBI in our HCWs. Results of extended stimulation assays suggest that many of our IR HCWs have indeed been sensitized to Mycobacterium tuberculosis. It is possible that the QFT-G assay identifies those at higher reactivation risk rather than all previously infected, but, in the absence of long-term follow-up data, we should interpret negative QFT-G results with some caution.

QuantiFERON ®-TB Gold test in the identification of latent tuberculosis infection in immigrants

The identification and treatment of latent tuberculosis infection (LTBI) among immigrants are an effective strategy for TB control in developed countries. A new test for LTBI identification that uses more specific antigens of Mycobacterium tuberculosis is now commercially available under the brand name of QuantiFERON-TB Gold test. To compare QuantiFERON-TB Gold test to tuberculin skin testing (TST) for the detection of LTBI among immigrants from high endemic TB areas. Undocumented immigrants attending a district medical center were enrolled if they originated from high endemic TB areas, the time of arrival in Italy was < or = 5 years, had neither active TB disease nor known immunodeficiency status. The TST was applied according to standards and QuantiFERON-TB Gold test was performed following the manufacturer's instructions. Hundred subjects were included in the comparative analysis. TST was positive in 44% of subjects; 15% had a positive QuantiFERON-TB Gold test result. The total agreement between TST and QuantiFERON-TB Gold test was 71%, for a kappa statistics of 0.37; agreement was 100% for TST negative results, but only 34% for TST positive ones. In the multivariate logistic regression analysis, previous BCG vaccination was independently associated with a lower chance of disagreement between the tests. The prevalence of LTBI among immigrants was lower when determined by QuantiFERON-TB Gold; this may be a consequence of more specific MTB antigens used. Our results suggest that QuantiFERON-TB Gold may be used as confirmatory test for TST positive immigrants candidate to preventive therapy.

Detecting a low prevalence of latent tuberculosis among health care workers in Denmark detected by M. tuberculosis specific IFN-γ whole-blood test

The study was designed to estimate prevalence of tuberculosis infection among health care workers, using the tuberculin skin test (TST) and the new M. tuberculosis specific diagnostic whole-blood test and to identify possible risk factors. Employees at 2 departments of infectious diseases in Copenhagen were invited to enter the study. All attendants completed a questionnaire, had a TST and blood drawn for detection of interferon-gamma produced after stimulation with M. tuberculosis specific antigens ESAT-6 and CFP-10 (QuantiFERON-TB-Gold, Cellestis). 47 of 139 (34%) participants had a positive TST whereas only 2 of 139 (1%) had a positive QuantiFERON TB-Gold test (QFT-TB). 42 of 106 (40%) BCG vaccinated had positive TST (> or =12 mm) compared with 2 of 27 (7%) unvaccinated persons. Among 47 persons with positive TST, 42 (89%) were BCG- vaccinated. The 2 QFT-TB positive participants as well as the remaining 45 TST positive participants showed no sign of active tuberculous disease and were allocated to 6-month clinical follow-up, without medical therapy. Today, 1.5 y later, all remain healthy. The high rate of positive TST among health care workers was most probably due to BCG vaccination and not to infection with M. tuberculosis. The overall transmission rate determined by QFT-TB was found to be very low. The QFT-TB may be useful in distinguishing persons with latent TB infection from persons with positive TST due to BCG vaccination and its use may reduce anxiety.