• Tuberculosis and Respiratory Diseases
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• v.81 no.4
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• pp.274-280
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• 2018

Background: The risk of tuberculosis (TB) infection among health care workers (HCWs) is higher than as noted among workers in the general population. The prevalence and risk factors of TB infection among HCWs were assessed in a tertiary hospital in South Korea, resulting in a conclusion of an intermediate TB burden within the country. Methods: This cross-sectional study enrolled HCWs who underwent a QuantiFERON-TB Gold In-Tube (QFT-GIT) test to detect the presence of a latent TB infection (LTBI), in patients admitted to a tertiary hospital in South Korea in 2017. The departments of the hospital were divided into TB-related and TB-unrelated departments, which were based on the risk of exposure to TB patients. In this sense, the risk factors for LTBI, including current working in the TB-related departments, were analyzed. Results: In this case, a total of 499 HCWs (54 doctors, 365 nurses and 80 paramedical personnel) were enrolled in this study. The median age of the subjects was 31 years (range, 20-67 years), 428 (85.8%) were female, and 208 (41.7%) were working in the TB-related departments. The prevalence of LTBI was 15.8% based on the QFT-GIT. Additionally, the prevalence of experience of exposure to pre-treatment TB patents was higher among HCWs working in the TB-related departments, than among HCWs working in the TB-unrelated departments (78.8% vs. 61.9%, p<0.001). However, there was no significant difference in the prevalence of LTBI between the two groups (17.3% vs. 14.8%, p=0.458). On a review of the multivariate analysis, only the factor of age was independently associated with an increased risk of LTBI (p=0.006). Conclusion: Broadly speaking, the factor of age was associated with an increased risk of LTBI among the HCWs in South Korea. However, those workers current working in the TB-related departments was not associated with an increased risk of LTBI.

• Tuberculosis and Respiratory Diseases
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• v.83 no.4
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• pp.283-288
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• 2020

Background: Latent tuberculosis (TB) infection among TB contacts is diagnosed using plain chest radiography and interferon-gamma release assays (IGRAs). However, plain chest radiographs often miss active TB, and the results of IGRA could fluctuate over time. The purpose of this study was to elucidate changes in the results of the serial IGRAs and in the findings of the serial submillisievert chest computed tomography (CT) scans among the close contacts of active pulmonary TB patients. Methods: Patients age 20 or older with active pulmonary TB and their close contacts were invited to participate in this study. Two types of IGRA (QuantiFERON-TB Gold In-Tube assay [QFT-GIT] and the T-SPOT.TB test [T-SPOT]) and submillisievert chest CT scanning were performed at baseline and at 3 and 12 months after enrollment. Results: In total, 19 close contacts participated in this study. One was diagnosed with active pulmonary TB and was excluded from further analysis. At baseline, four of 18 contacts (22.2%) showed positive results for QFT-GIT and T-SPOT; there were no discordant results. During the follow-up, transient and permanent positive or negative conversions and discordant results between the two types of IGRAs were observed in some patients. Among the 17 contacts who underwent submillisievert chest CT scanning, calcified nodules were identified in seven (41.2%), noncalcified nodules in 14 (82.4%), and bronchiectasis in four (23.5%). Some nodules disappeared over time. Conclusion: The results of the QFT-GIT and T-SPOT assays and the CT images may change during 1 year of observation of close contacts of the active TB patients.

• Tuberculosis and Respiratory Diseases
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• v.82 no.4
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• pp.298-305
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• 2019

Background: Tuberculosis (TB) causes substantial health burden to the Korean military. This study aims to assess the impact of infectious TB cases on close and casual contacts in the Korean Army settings based on contact investigation data. Methods: Six Army units with infectious TB cases from September 2012 to May 2013 were enrolled in the study. We analyzed the clinical data from close and casual contacts screened using the tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube to identify latent tuberculosis infection (LTBI) cases. For the control group, 286 military conscripts with no reported TB exposure were tested by TST only. Results: Of the 667 contacts of index cases, LTBI cases identified were as follows: 21.8% of close contacts of smearpositive cases (71/326), 8.5% of casual contacts of smear-positive cases (26/305), and 2.8% of close contacts of smearnegative cases (1/36). In the control group, 16.8% showed positivity in TST. In a multivariate analysis, having stayed in the same room or next room with TB patients was identified as a risk factor of LTBI. Conclusion: Using the data from TB contact investigations in the Korean Army units, we found an overall LTBI rate of 14.7% among the contacts screened. This study demonstrates that contacts living in the same building, especially the same room or next room, with TB patients are at a high risk of acquiring LTBI, serving as additional evidence for defining close and casual contacts of a TB patient with regard to Army barrack settings.

• Tuberculosis and Respiratory Diseases
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• v.73 no.4
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• pp.234-238
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• 2012

Recently, interferon gamma releasing assay has been recommended to compensate the tuberculin skin test (TST) for screening for latent tuberculosis infection (LTBI). Although it improved the detection of LTBI before treatment with tumor necrosis factor blocker, its application to immune suppressed patients is limited. We report a case of peritoneal tuberculosis (TB) developed in a patient who tested positive for TST and QuantiFERON-TB Gold (QFT-G) before infliximab therapy, to emphasize the importance of monitoring during treatment. A 52-year-old woman presented with abdominal distension. She had been diagnosed with seropositive rheumatoid arthritis six years ago. She had started taking infliximab six months ago. All screening tests for TB were performed and the results of all were negative. At admission, the results of repeated TST and QFT-G tests were positive. Histopathological examination confirmed peritoneal TB. The patient started anti-TB therapy and the symptoms were relieved.

• The Korean journal of internal medicine
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• v.33 no.6
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• pp.1241-1251
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• 2018

Background/Aims: To estimate the level of agreement and positivity rates of latent tuberculosis infection (LTBI) tests prior to the use of tumor necrosis factor (TNF) inhibitors in relation to underlying rheumatic diseases and endemic tuberculosis levels. Methods: The Ovid-Medline, Embase, and Cochrane Libraries were searched for articles before October 2013 involving LTBI screening in rheumatic patients, including rheumatoid arthritis (RA), ankylosing spondylitis (AS), juvenile idiopathic arthritis (JIA), and psoriatic arthritis. Results: In pooled analyses, 5,224 rheumatic patients had undergone both a tuberculin skin test (TST) and an interferon-gamma release assay (IGRA) before TNF inhibitors use. The positivity of TST, QuantiFERON-TB Gold In Tube (QFT-GIT), and T-SPOT.TB (T-SPOT) tests were estimated to be 29%, 17%, and 18%, respectively. The agreement percentage between the TST and QFT-GIT, and between the TST and T-SPOT were 73% and 75%. Populations from low-to-moderate endemic TB presented with slightly less agreement (71% between TST and QFT-GIT, and 74% between TST and T-SPOT) than patients from high endemic countries (73% between TST and QFT-GIT, and 81% between TST and T-SPOT). By underlying disease stratification, a lower level of agreement between TST and QFT-GIT was found among AS (64%) than among JIA (77%) and RA patients (73%). Conclusions: We reaffirm the current evidence for accuracy of LTBI test done by TST and IGRA among rheumatic patients is inconsistent. Our stratified analysis suggests different screening strategies might be needed in clinical settings considering the endemic status in the patient's country of origin and the precise nature of underlying diseases.

• Tuberculosis and Respiratory Diseases
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• v.73 no.4
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• pp.219-223
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• 2012

Background: We investigated the prevalence of latent tuberculosis infection (LTBI) among medical students in South Korea. Methods: Students from one medical school, who were in second- or third-year classes before clerkship course, were enrolled for three consecutive years in the study. A standard questionnaire was given to each participant, and tuberculin skin test (TST), QuantiFERON-TB GOLD In-Tube (QFT-GIT) assay, and chest radiography were performed. Results: A total of 153 participants were enrolled in the study. The mean age of the subjects was $21.9{\pm}0.9$ years, 105 (68.6%) were male, and 132 (86.3%) had been vaccinated with Bacille Calmette-Gu$\acute{e}$rin (BCG). Four students (2.6%) had a history of contact with tuberculosis (TB) patients during medical practice. No abnormal chest radiograph findings were found for any of the subjects. Of the 153 subjects, 23 (15.0%) tested positive for the TST, and 8 (5.2%) tested positive for the QFT-GIT. The agreement between the two tests was determined to be 0.34 using kappa coefficients. Of the four students who had a history of contact with TB patients, only one subject tested positive for both tests, and the other three students tested negative for both tests. Conclusion: A low prevalence of LTBI was found among medical students before clerkship course in South Korea.

• Journal of Korean Biological Nursing Science
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• v.21 no.4
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• pp.300-307
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• 2019

Purpose: The purpose of this study was to provide basic data on the infection prevention management program, which is one of the infectious disease control program by identifying the prevalence and risk factors of latent tuberculosis infection (LTBI) in healthcare workers. Methods: We surveyed a total of 3,046 LTBI test results, including those of 2,269 existing staff and 777 new employees. An interferon-gamma release assay (IGRA) for the diagnosis of LTBI was performed using QuantiFERON^®-TB Gold In-Tube (QFT-IT). The risk factors of LTBI were analyzed using logistic regression analysis. Results: The overall prevalence of LTBI was 16.0% (487/3,046). The prevalence of LTBI in the existing staff was 17.9% (406/2,269) and the prevalence of LTBI in new employees was 10.4% (81/777). Multivariate logistic regression analysis revealed that the risk factors of latent tuberculosis infection among the existing staff were gender, age and work period wheres, the risk factor amongst the new employees depended on their age. Conclusion: The LTBI was not related to the type of occupation and work unit. Therefore, while establishing an infection control program for the prevention of tuberculosis infection at medical institurions, institutional heads and infection control experts should encompass a policy for all the employees.

• Annals of dermatology
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• v.30 no.6
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• pp.716-720
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• 2018

Perforating granuloma annulare (PGA), a rare variant of granuloma annulare, is characterized by transepidermal elimination of altered collagen that clinically manifests an umbilicated papule with a central crust. It can be confused with papulonecrotic tuberculid (PNT) because of their similar appearance. Unlike PGA, PNT is usually related to tuberculosis infection with a typical histologic finding of wedgeshaped dermal necrosis. Here, we report the first Korean case of PGA mimicking PNT both clinically and histologically. A 43-year-old Korean woman presented with erythematous papules localized on the extensor surface of her limbs for one year. Some of these papules had a central umbilication or a crust. Regarding comorbidity, she had latent tuberculosis diagnosed with $QuantiFERON^{(R)}-TB$ Gold test about five months ago. She was on antituberculous medication. Initially, a diagnosis of papulonecrotic tuberculid accompanied by latent tuberculosis was considered. However, despite taking the antituberculous medication for five months, her skin lesions were not improved. Biopsy specimen from her arm lesion showed wedge-shaped area of necrosis in the dermis. Additionally, there were multiple focal mucin depositions and palisading granulomatous inflammation throughout the dermis. A diagnosis of PGA was made and she was treated with topical corticosteroid. After two weeks of applying topical corticosteroid, most of her skin lesions disappeared, leaving some hyperpigmented scars.

• Pediatric Infection and Vaccine
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• v.23 no.1
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• pp.18-24
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• 2016

Purpose: There is a the great diagnostic challenge in pediatric tuberculosis especially in high burden setting. The purpose of this preliminary study is to evaluate the agreement between tuberculin skin test (TST) and interferon-gamma release assay (IGRA) including T-SPOT$^{(R)}$.TB and QuantiFERON$^{(R)}$-TB Gold (QFT-G) in Korean children. Method: This retrospective study included children and adolescents who visited to Asan Medical Center to evaluate tuberculosis infection using at least two assays of TST, T-SPOT.TB and QFT-G, from January 2014 to April 2015. Results: A total of 20 patients were included, whose median age was 13.3 years (range, 3.8-18.1 years), and all of them had history of BCG vaccination. Eleven patients had underlying diseases including 7 patients with immunosuppressant medication. The concordance rate between T-SPOT.TB and QFT-G was 90%. However, the concordance rate between TST and T-SPOT.TB was 50%, and between TST and QFT-G was 42.9%. Specificity for the diagnosis of tuberculosis infection of T-SPOT.TB, QFT-G, and TST was 93.3%, 86.7%, and 58.3%, respectively. Conclusions: Although there was a discrepancy between TST and IGRA to diagnose tuberculosis, agreement between T-SPOT.TB and QFT-G was relatively high. Further prospective study to validate the clinical usefulness of each assay for immunologic evidence of tuberculosis infection in Korean children will be mandatory.

• Tuberculosis and Respiratory Diseases
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• v.59 no.4
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• pp.406-412
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• 2005

Background : Recently, two commercialized whole-blood assays, $QuantiFERON^{(R)}-TB$ Gold (QFT) and T $SPOT-TB^{(R)}$ (SPOT), which measure the $IFN-{\gamma}$ released in the whole blood after being incubation with mycobacterial antigens, were approved for the diagnosis of a latent tuberculosis infection (LTBI). However, there is data on whether or not the previously used PPD skin tests (TST) have any influence on the diagnostic ability of these ex-vivo $IFN-{\gamma}$ assays. Methods : Forty-six 15 year-old students who did not appear to be infected with Mycobacterium tuberculosis were enrolled in this study. The peripheral blood was collected and used for two $IFN-{\gamma}$ assays. The $IFN-{\gamma}$ assays and TST were performed at the baseline ($1^{st}$). The TST was repeated two months later ($2^{nd}$), and the $IFN-{\gamma}$ assays were repeated two ($2^{nd}$) and four months ($3^{rd}$) later only in those subjects who had negative results at the baseline in both the $IFN-{\gamma}$ assays and TST. An induration size > 10 mm was considered to be positive in the TST. Results : The mean TST value was $3.1{\pm}5.4mm$ (range: 0-20). Of the 46 subjects examined, 13 subjects (28.3%) showed positive results in the two-step TST. Nine (19.6%) were SPOT-positive and only one (2.2%) was QFT-positive. The $2^{nd}$ and $3^{rd}$ QFT were carried out in 23 and 25 all-negative subjects, respectively, and all showed negative results. The $2^{nd}$ SPOT was performed in 23 subjects and only one (4.3%) showed a weak-positive result. Conclusion : Even though there were some discrepancies in the results of the two ex-vivo $IFN-{\gamma}$ assays, it appears that their results were not influenced by a previous TST carried out in two or four months earlier.