Avances en tuberculosis en el 54° Congreso Chileno de enfermedades respiratorias. 3a parte: Prevención de la tuberculosis activa mediante el tratamiento de la tuberculosis latente / Advances in tuberculosis at the 54th Chilean Congress of Respiratory Diseases. Part 3: prevention of active tuberculosis by treating latent tuberculosis

La infección tuberculosa latente (ITL) es un estado asintomático de la infección por Mycobacterium tuberculosis incapaz de transmitir la infección a otros, pero con el potencial de originar una tuberculosis (TBC) activa en el infectado, especialmente ante la presencia de factores de riesgo inmunológico. Es importante en personas de riesgo de desarrollar TBC reconocer la ITL utilizando test como la reacción a la tuberculina (PPD o TST) y los ensayos de liberación de Interferón-γ (IGRAs). Sin embargo, estos tests tienen limitaciones en su capacidad de predicción de riesgo de evolución de infección a enfermedad lo que conlleva a tener que tratar muchas personas para evitar algún caso de enfermedad. Nuevos tests se encuentran en desarrollo para mejorar la sensibilidad de reconocimiento de la ITL, distinguir infecciones recientes (que tienen el mayor riesgo de progresión a enfermedad) e incluso con la capacidad de detectar enfermedad subclínica o inicial. Para reducir la probabilidad de enfermar por TBC se utilizan tratamientos preventivos con fármacos, pero la cobertura mundial de esta terapia es reducida y la adherencia a terapias auto-administradas, como en el caso del uso de isoniazida diaria oral, es también baja. Otro problema de esta terapia son los riesgos de reacciones adversas (hepatitis, erupciones cutáneas) aunque no frecuentes. La recomendación de terapia actual de la ITL incluye el uso de rifamicinas y sus derivados. La asociación de isoniazida con rifapentina en una dosis semanal durante tres meses, administrada bajo supervisión, es la terapia de primera línea para mayores de 2 años, mostrando menos riesgo de hepatotoxicidad y mayor adherencia.

Latent Tuberculosis infection (LTBI) is the asymptomatic state of infection caused by Mycobacterium tuberculosis. Although untransmissible, LTBI can progress to active tuberculosis (TB), especially in people with immune risk factors. It is important to recognize LTBI in people at risk of developing TB; tuberculin skin test (PPD or TST) or interferon-γ release assays (IGRAs) are current diagnostic tests. However, these tests have limitations in their ability to predict subjects who will evolve from infection to disease; consequently, a large number of people with LTBI need treatment to avoid a reduced number of future TB disease cases. Newer tests are under development to improve the sensitivity in recognizing LTBI, distinguish recent infections with highest risk of progression to disease, and even be able to detect initial subclinical disease. Antimicrobial preventive treatment effectively reduces the probability of getting sick with TB, but worldwide availability of TB preventive therapy is limited, and adherence to self-administered therapies, as in the case of the use of daily oral isoniazid, is low. Adverse reactions risk (hepatitis, skin rash) although infrequent, is another problem with these therapies. Currently, LTBI management guidelines include regimens with use of rifamycins and their derivatives. The combination of isoniazid and rifapentine in a weekly dose for three months administered under supervision is the first line choice for LTBI therapy in those over 2 years of age, showing less hepatoxicity risk and greater adherence.

Tuberculosis latente: diagnóstico y tratamiento actual / Latent tuberculosis: current diagnosis and treatment

Resumen La infección tuberculosa latente (TL) afecta al 23% de la población y constituye un reservorio de tuberculosis (TBC) ya que 10% progresa hacia una TBC. La TL se reconoce por pruebas como la tuberculina (PPD o TST) y los ensayos de liberación de Interferón gama (IGRAs). La sensibilidad de IGRAs (versión Quantiferon TB Gold plus) es 94% y del PPD 77%. La especificidad del Quantiferon TB Gold Plus es 97% y del PPD 68%. El valor predictivo de progresión a TBC activa de estas pruebas es bajo (PPD: 1,5%, IGRAs: 2,7%) pero mejora en personas de alto riesgo de contraer TBC (PPD: 2,4%, IGRAs: 6,8%). Las personas con pruebas negativas que posteriormente presentan viraje (prueba positiva) tienen mayor riesgo de progresión a TBC activa. Estas pruebas son útiles en el seguimiento de contactos intradomiciliarios, extranjeros de países con altas tasas de TBC, inmunosuprimidos, enfermedad renal crónica, diabetes, silicosis y secuelas pulmonares de TBC no tratada. En la terapia de TL se utiliza isoniazida (H) auto-administrada por plazos de 6 a 12 meses con eficacia protectora de 60% y riesgo de toxicidad hepática de 2% pero con baja adherencia (50-70%). La asociación de H con rifapentina en dosis única semanal durante 12 semanas tiene eficacia de 81%, adherencia de 82% y baja toxicidad hepática (0,4%). Nuevos biomarcadores de TL y vacunas que mejoren la inmunidad en TL se encuentran en estudio. El tratamiento de la TL puede reducir la incidencia de TBC a largo plazo.

Latent tuberculosis infection (LT) affects 23% of the population and constitutes a reservoir of tuberculosis (TB) as 10% progresses to TB. LT is recognized by tests such as tuberculin (PPD or TST) and Interferon gamma release assays (IGRAs). The sensitivity of IGRAs (Quantiferon TB Gold plus version) is 94% and PPD 77%. The specificity of Quantiferon TB Gold Plus is 97% and PPD 68%. The predictive value of progression to active TB of these tests is low (PPD: 1.5%, IGRAs: 2.7%) but improves in people at high risk of contracting TB (PPD: 2.4%, IGRAs: 6.8%). People with negative tests who subsequently turn around (positive) have a higher risk of progression to active TB. These tests are useful in the follow-up of intra-household contacts, foreigners from countries with high rates of TB, immunosuppressed, chronic kidney disease, diabetes, silicosis and pulmonary sequelae of untreated TB. In LT therapy, self-administered isoniazid (H) is used for periods from 6 to 12 months with protective efficacy of 60% and risk of liver toxicity of 2%, but with low adherence (50-70%). The association of H with rifapentine in a single weekly dose for 12 weeks has efficacy of 81%, adherence of 82% and low liver toxicity (0.4%). New LT biomarkers and vaccines that improve immunity in LT are under study. Treatment of LT may reduce the incidence of TB in the long term.

Terapias biológicas y tuberculosis en pediatría / Biological therapies and tuberculosis in pediatrics

En los últimos años, ha habido un aumento sostenido del uso de terapias inmunomoduladoras como las terapias biológicas y en un período más reciente, de las terapias con moléculas pequeñas. Estos tratamientos constituyen un factor de riesgo más para enfermar de tuberculosis en adultos y aunque en menor grado, también en niños, especialmente con el uso de anti TNF-α, por lo que antes de iniciar una terapia biológica, hay que descartar la tuberculosis activa y la latente. En el tratamiento de una tuberculosis activa producida por un biológico se debe prolongar la etapa de continuación a 9 meses. Es importante el seguimiento clínico prolongado en años de quienes usan o han completado el uso de estas terapias. Hay que posponer la vacunación BCG en los hijos de madres que usaron terapias biológicas durante la gestación hasta la edad 6 a 12 meses de los niños. El foco de esta revisión está centrado en la tuberculosis por progresión de una forma latente a una activa o por un contacto estrecho con una persona con tuberculosis pulmonar en pacientes que reciben terapias biológicas anti TNF alfa de uso inmunoreumatológico.

In recent years, there has been a sustained increase in the use of immunomodulatory therapies such as biologic therapies and, more recently, small molecule therapies. Those therapies have become another risk factor for tuberculosis in adults and, although to lesser degree, also in children, especially some of them, such as anti-TNF α. Before starting biological therapy, active tuberculosis and latent tuberculosis must be ruled out. In the treatment of active tuberculosis caused by a biologic, the continuation stage should be extended to 9 months. Long-term clinical follow-up in years of those who use them or have completed their use, is important. BCG vaccine should be postponed in children of mother who used biologic therapies during pregnancy until the children ́s age 6 to 12 months. The focus of this review is centered on tuberculosis due to progression from a latent to an active form or due to close contact with a person with pulmonary tuberculosis in patients receiving anti-TNF alpha biological therapies for immunorheumatology use.

Latent tuberculosis screening before kidney transplantation in the South of Brazil / Rastreamento de tuberculose latente antes do transplante renal no Sul do Brasil

Abstract Background: Tuberculosis (TB) is a prevalent infection after kidney transplantation (KT) in high-burden countries. Latent tuberculosis infection (LTBI) screening includes previous TB history, chest radiograph findings, and tuberculin test (TST) and/or interferon-gamma release assays (IGRAs) results. We aimed to compare our routine LTBI screening of KT candidates and living donors (LD) with their IGRA results, and evaluate if this would improve isoniazid (INH) treatment referral. Methods: We evaluated adult KT candidates and LD with complete routine LTBI screening and QuantiFERON-TB® Gold In-Tube (QFT) testing. Blood samples were collected from April 4th, 2014 to October 31st, 2018, with follow-up until October 31st, 2019. Results: There were 116 KT recipients, with 30% QFT-positive results. Positive QFT was associated with past TB history (p=0.007), positive TST (p<0.0001), residual radiographic lesions (p=0.003), and diabetes (p=0.035). There were 25 LD, 40% had positive QFT. Positive QFT was associated with a positive TST (p=0.002). Positive QFT results increased INH referral in 80%. Post-transplant TB incidence was 2.6% in a median follow-up of 2 (1-33) months. No variables were associated with post-transplant TB. TB patients had inferior, although non-significant, 5-year graft survival (66.7% vs. 76.5%) (p = 0.402). Conclusion: In the present study, the association of QFT to our routine LTBI screening incremented INH treatment referral, but there was still a high incidence of post-transplant TB, possibly related to other forms of infection, such as new exposure and donor transmission.

Resumo Histórico: Tuberculose (TB) é uma infecção relativamente comum pós-transplante renal (TR) em países com alta prevalência da doença. O rastreamento de infecção latente por tuberculose (ILTB) inclui histórico prévio de TB, achados de radiografia do tórax, resultados do teste tuberculínico (TT) e/ou de ensaio de liberação de interferon-gama (IGRAs). Nosso objetivo foi comparar nossa avaliação de rotina de candidatos ao TR e doadores vivos (DV) com seus resultados de IGRA, avaliando se aumentaria o encaminhamento para tratamento com isoniazida (INH). Métodos: Avaliamos candidatos adultos ao TR e DV com rastreamento para ILTB de rotina completo e coleta de testes QuantiFERON-TB® Gold In-Tube (QFT). Coletamos amostras sanguíneas de 4 de Abril, 2014 - 31 de Outubro, 2018, com acompanhamento até 31 de Outubro, 2019. Resultados: Avaliamos 116 receptores de TR, 30% sendo QFT-positivo. QFT positivo foi associado ao histórico prévio de TB (p=0,007), TT positivo (p<0,0001), lesões radiográficas residuais (p=0,003), diabetes (p=0,035). Avaliamos 25 DV, 40% apresentaram QFT positivo. QFT positivo foi associado a TT positivo (p=0,002). Resultados positivos do QFT aumentaram o encaminhamento para INH em 80%. A incidência de TB pós-transplante foi 2,6% em uma mediana de acompanhamento de 2 (1-33) meses. Nenhuma variável foi associada à TB pós-transplante. Pacientes com TB tiveram sobrevida do enxerto em 5 anos inferior, embora não-significativa (66,7% vs. 76,5%) (p = 0,402). Conclusão: Neste estudo, a associação do QFT à nossa avaliação de ILTB de rotina aumentou o encaminhamento para tratamento com INH, mas ainda houve alta incidência de TB pós-transplante, possivelmente relacionada a outras formas de infecção, como nova exposição e transmissão pelos doadores.

Potencial do teste IGRA (Interferon Gama Release Assay) para o diagnóstico de tuberculose ocular. Revisão e análise comparativa com o teste tuberculínico cutâneo (PPD) / The potential of the IGRA (Interferon Gamma Release Assay) test for the diagnosis of ocular tuberculosis. Review and comparative analysis with the tuberculosis skin test

Resumo A detecção precisa da infecção latente por tuberculose está se tornando cada vez mais importante devido ao aumento do uso de medicamentos imunossupressores e da epidemia do vírus da imunodeficiência humana, o que aumentou o risco de reativação à tuberculose ativa (TB). O Teste IGRA QuantiFERON® TB Gold apresenta vantagens frente ao teste de PPD como por exemplo, requer somente uma coleta de amostra sanguínea ; não há necessidade que o paciente retorne ao laboratório para leitura e interpretação dos resultados; Os resultados são objetivos, não requerem interpretação do leitor ou interferência de critérios subjetivos; trata-se de um teste in vitro, portanto não há "efeito booster" (potenciação da reação tuberculínica); o teste não é afetado por vacinação prévia por BCG ou infecção por outras espécies de micobactérias. Limitações são descritas, apesar de raras, como reações cruzadas deste método com infecções por algumas espécies de micobactérias não-tuberculosis (incluindo Mycobacterium kansasii, Mycobacterium szulgai e Mycobacterium marinum). Ainda há poucos dados sobre o teste IGRA em certas populações, como por exemplo, em crianças, pacientes imunocomprometidos e mulheres grávidas. Nestes grupos, a interpretação do teste pode ser difícil e mais estudos se fazem necessários.

Abstract Precise detection of latent tuberculosis infection is becoming increasingly important due to increased use of immunosuppressive drugs and the human immunodeficiency virus epidemic , which increased the risk of reactivation to active tuberculosis (TB).The QuantiFERON® TB Gold IGRA Test has advantages over the skin test for TB, otherwise known as a Mantoux tuberculin test, for example, requires only a blood sample collection; there is no need for the patient to return to the laboratory for reading and interpretation of the results; The results are objective, do not require interpretation of the reader or interference of subjective criteria; it is an in vitro test, so there is no "booster effect" (potentiation of the tuberculin reaction); the test is not affected by prior BCG vaccination or infection with other species of mycobacteria. Limitations are described, although rare, as cross-reactions of this method with infections by some species of non-tuberculosis mycobacteria (including Mycobacterium kansasii, Mycobacterium szulgai and Mycobacterium marinum). There is still little data on the IGRA test in certain populations, such as in children, immunocompromised patients and pregnant women. In these groups, the interpretation of the test can be difficult and more studies are needed.

Diagnosis and treatment of latent tuberculosis infection

In order to eliminate tuberculosis worldwide by 2050, effective management of latent tuberculosis infection is essential, and policy-makers have begun to recognize the importance of scaling up preventive therapy. The current guideline recommends targeted latent tuberculosis infection testing that identifies high-risk groups based on risk stratification for progression from latent infection to active disease. Both the tuberculin skin test and interferon-gamma releasing assay have a similar diagnostic efficacy for predicting progression to active tuberculosis. The Korean guideline recommends 9-month isoniazid monotherapy as the standard treatment; however, more evidence supports that short course rifampicin-based regimen is both more effective and tolerable than isoniazid monotherapy.

Proposal to Revise the Screening Test for Latent Tuberculosis Infection in Close Contacts at Elementary Schools in Korea / 예방의학회지

The 2018 National Guideline for Tuberculosis Control, which was published by the Korea Centers for Diseases Prevention and Control (KCDC), mandates conducting an epidemiological survey among close contacts of active tuberculosis patients at public institutions such as schools. In the procedure for these surveys, the tuberculin skin test (TST) is mandated as the screening test for latent tuberculosis infection in elementary school students. However, several guidelines recommend using the interferon-gamma releasing assay (IGRA) for contacts aged over 5 years with a Bacillus Calmette–Guérin vaccination history. The main reason for this is that IGRA has a higher specificity and lower false positive rate than TST. In addition, IGRA requires only a single visit to draw blood and the results are available within 24 hours. These advantages could promote cooperation from both parents and students in conducting these surveys. Thus, these findings regarding the benefits of IGRA for surveys of close contacts at elementary schools should be incorporated into the KCDC guideline.

The Performance of the Agility System for Interferon Gamma Release Assay Using QuantiFERON TB Gold In-Tube Assay / 임상검사와정도관리

BACKGROUND: As stated in ‘The Action Strategy for Tuberculosis-Free Korea,’ last March, high-throughput, large-scale analytical instruments for interferon gamma release assays (IGRA) are demanded by many clinical laboratories using the QuantiFERON-TB Gold In-Tube assay (Cellestis/Qiagen, Australia). Agility (Dynex Technologies, USA) is an automated high-throughput enzyme linked immunosorbent assay analyser. The present study aimed to evaluate its accuracy and speed. METHODS: Pooled plasma was prepared using samples obtained after IGRA testing. Analyses of precision, linearity, cut-off evaluation, and comparison with conventional methods were performed for multiple Agility instruments according to the Clinical and Laboratory Standards Institute EP5-A3, EP6-A, EP9-A3 and EP12-A2 guidelines. The turnaround time and throughput were also analysed. RESULTS: The coefficient of variation range was 2.48%–4.0%, 7.01%–11.17%, and 9.69%–14.84% for the repeatability, between-run precision, and between-day precision analyses, respectively. The linearity ranged from 0 to 10.541. Comparison analysis presented a high concordance of Agility with the conventional instrument, DS2 (Dynex Technologies), and manual method for IGRA. The cut-off value of 0.35 IU/mL was well compatible with the C50. It was identified that the C50±20% contained the C5–C95 interval. The average turnaround time was 3.84 hours, from the submission of pre-treated samples to the reporting of results. The throughput was determined to be 290 tests during a routine working time of 8 hours. CONCLUSIONS: Agility showed high precision, linearity, concordance, and had a 2.5 times faster throughput than with the conventional and manual method. It could be useful for large-scale IGRA testing in latent tuberculosis infection screening project. Samples within C50±20% are suspected to show relatively low reporducible results of high inversion between postivie and negative.

Experiences of Latent Tuberculosis Infection Treatment for the North Korean Refugees / 결핵

BACKGROUND: Tuberculosis (TB) is increasing in immigrants. We aimed to investigate the current status of latent tuberculosis infection (LTBI) treatment for North Korean Refugees (NKR) compared to South Koreans Contacts (SKC). METHODS: TB close contacts in a closed facility of SKC and NKR who underwent LTBI screening in a settlement support center for NKR were analyzed retrospectively. RESULTS: Among tuberculin skin test (TST) ≥10 mm (n=298) reactors, the males accounted for 72.2% in SKC (n=126) and 19.5% in NKR (n=172) (p<0.01). The mean age was higher in South Korea (42.8±9.9 years vs. 35.4±10.0 years, p<0.01). Additionally, the mean TST size was significantly bigger in NKR (17.39±3.9 mm vs. 16.57±4.2 mm, p=0.03). The LTBI treatments were initiated for all screened NKR, and LTBI completion rate was only 68.0%. However, in NKR, LTBI treatment completion rate was significantly increased by shorter 4R regimen (odds ratio [OR], 9.296; 95% confidence interval [CI], 4.159–20.774; p<0.01) and male (OR, 3.447; 95% CI, 1.191–9.974; p=0.02). CONCLUSION: LTBI treatment compliance must be improved in NKR with a shorter regimen. In addition, a larger study regarding a focus on LTBI with easy access to related data for NKR should be conducted.

Latent tuberculosis infection in patients with rheumatic diseases / Infecção latente por tuberculose em pacientes com doenças reumatológicas

ABSTRACT Most people infected by Mycobacterium tuberculosis (Mtb) do not have any signs or disease symptoms, a condition known as latent tuberculosis infection (LTBI). The introduction of biological agents, mainly tumor necrosis factor (TNF) inhibitors, for the treatment of immune-mediated diseases such as Rheumatoid Arthritis (RA) and other rheumatic diseases, increased the risk of reactivation of LTBI, leading to development of active TB. Thus, this review will approach the aspects related to LTBI in patients with rheumatologic diseases, especially those using iTNF drugs. For this purpose it will be considered the definition and prevalence of LTBI, mechanisms associated with diseases and medications in use, criteria for screening, diagnosis and treatment. Considering that reactivation of LTBI accounts for a large proportion of the incidence of active TB, adequate diagnosis and treatment are crucial, especially in high-risk groups such as patients with rheumatologic diseases.

RESUMO A maioria das pessoas infectadas por Mycobacterium tuberculosis (Mtb) não possui sinais ou sintomas da doença, quadro conhecido como infecção latente por tuberculose (ILTB). A introdução de agentes biológicos, sobretudo inibidores do fator de necrose tumoral (iTNF), para o tratamento de doenças imunomediadas, como artrite reumatoide (AR) e outras doenças reumatológicas, aumentou o risco de reativação de ILTB, levando ao desenvolvimento de tuberculose (TB) ativa. Assim, esta revisão abordará os aspectos relacionados à ILTB em pacientes com doenças reumatológicas, especialmente naqueles em uso de medicamentos iTNF. Para tanto, serão considerados a definição e a prevalência de ILTB, os mecanismos associados às doenças e às medicações em uso, bem como os critérios para rastreamento, diagnóstico e tratamento da ILTB. Como a reativação da ILTB é responsável pela grande proporção de casos de TB ativa, o diagnóstico e o tratamento adequados são cruciais, principalmente em grupos de alto risco, como os pacientes com doenças reumatológicas.

Neutrophil CD64 expression levels in IGRA-positive individuals distinguish latent tuberculosis from active disease

BACKGROUND CD64 (FcγR1) is a high-affinity receptor for monomeric IgG1 and IgG3. Circulating neutrophils express very low amounts of CD64 on their surface. OBJECTIVES Our primary aim was to investigate the utility of neutrophil CD64 surface expression as a biomarker of active pulmonary tuberculosis (TB). We hypothesised that elevated neutrophil CD64 expression in TB infection would be associated with interferon gamma (IFN-γ) as an inducer of CD64 expression. METHODS The expression level of CD64 per neutrophil (PMN CD64 index) was quantitatively measured with flow cytometry using a Leuko64 kit in samples from patients with TB and latent TB infection (LTBI) as well as healthy controls, as part of a prospective cohort study in Brazil. FINDINGS The PMN CD64 index in patients with TB was higher than that in healthy controls and LTBI. Receiver operating characteristic curve analyses determined that the PMN CD64 index could discriminate patients with TB from those with LTBI and healthy individuals. PMN CD64 index levels returned to baseline levels after treatment. CONCLUSIONS The positive regulation of CD64 expression in circulating neutrophils of patients with active TB could represent an additional biomarker for diagnosis of active TB and could be used for monitoring individuals with LTBI before progression of TB disease.

Good Agreement between an Interferon Gamma Release Assay and Tuberculin Skin Tests in Testing for Latent Tuberculosis Infection among HIV-Infected Patients in Indonesia

BACKGROUND: Latent tuberculosis infection is a condition where there is a persistent immune response to Mycobacterium tuberculosis without clinical manifestations of tuberculosis. Currently, there is no gold standard to diagnose latent tuberculosis infection. The tuberculin skin test and interferon-gamma release assay are currently used to diagnose latent tuberculosis infection. However, studies have shown inconsistencies regarding the level of agreement between these tests in different settings. In this study, we aimed to evaluate the agreement between these two tests for diagnosing latent tuberculosis infection in human immunodeficiency virus (HIV)-infected individuals. METHODS: We screened HIV patients with no clinical symptoms of tuberculosis, a normal chest X-ray, and no history of tuberculosis or use of antituberculous drugs. Participants were tested with tuberculin skin test (TST) and T-SPOT.TB (an interferon gamma release assay) simultaneously. Participants' HIV stage was determined by measuring the level of CD4+ T-lymphocytes. Tuberculosis status was confirmed by sputum examination using GeneXpert. The level of agreement between the TST and T-SPOT.TB results was measured using Cohen's κ coefficient. RESULTS: Of the 112 participants, 20 had a positive T-SPOT.TB test result, and 21 had a positive TST result. The TST and T-SPOT.TB test results showed a high level of agreement (κ = 0.648, P < 0.001). Performance of the tests did not vary with CD4+ level. However, in participants with CD4+ < 200 cells/mm³, T-SPOT.TB detected more latent tuberculosis infections than the TST. CONCLUSION: There was good agreement between the TST and T-SPOT.TB results of latent tuberculosis infection in participants. TST is the preferred test for diagnosing latent tuberculosis infection in HIV-infected patients, especially in resource-limited settings, because it is simple and cost-effective. However, T-SPOT.TB may be useful to rule out latent tuberculosis infection in patients with severe immunodeficiency.

Analysis of Prevalence and Risk Factors for Latent Tuberculosis Infection among Healthcare Workers

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.

Interferon-gamma release assay performance in northeastern Brazil: influence of the IFNG+874 A>T polymorphism

ABSTRACT Introduction Latent tuberculosis infection diagnosis based on the release of interferon-gamma in cultures of peripheral blood cells stimulated with Mycobacterium tuberculosis antigens has replaced the tuberculin skin test in many countries with low tuberculosis prevalence. The IFN-γ production can be influenced by genetic polymorphisms, of which the IFNG + 874 (rs62559044) locus is the most studied. We investigated the possible influence of the IFNG + 874 A/T polymorphism on interferon-gamma test performance. Methods Patients diagnosed with pulmonary tuberculosis (75), volunteers with positive tuberculin skin test (70) and healthy volunteers with negative tuberculin skin test and no history of contact with tuberculosis (57) were evaluated regarding the IFNG + 874 genotype and the IFN-γ levels in whole blood cultures performed using an interferon-gamma commercial kit (QuantiFERON-TB® Gold In-Tube). Results IFN-γ production was not influenced by the IFNG + 874 genotype, regardless of antigen or mitogen-based stimulation, which suggests that other genes may influence IFN-γ production in response to mycobacteria. The IFNG + 874 polymorphism was found to exert no influence over QFT-IT test sensitivity in our study. Conclusions The IFNG + 874 polymorphism was not shown to influence QuantiFERON-TB® Gold In-Tube test performance in an admixed population from northeastern Brazil.

Treatment of Latent Tuberculosis Infection and Its Clinical Efficacy / 결핵

The role of the treatment for latent tuberculosis infection (LTBI) has been underscored in the intermediate tuberculosis (TB) burden countries like South Korea. LTBI treatment is recommended only for patients at risk for progression to active TB―those with frequent exposure to active TB cases, and those with clinical risk factors (e.g., immunocompromised patients). Recently revised National Institute for Health and Care Excellence (NICE) guideline recommended that close contacts of individuals with active pulmonary or laryngeal TB, aged between 18 and 65 years, should undergo LTBI treatment. Various regimens for LTBI treatment were recommended in NICE, World Health Organization (WHO), and Centers for Disease Control and Prevention guidelines, and superiority of one recommended regimen over another was not yet established. Traditional 6 to 9 months of isoniazid (6H or 9H) regimen has an advantage of the most abundant evidence for clinical efficacy―60%–90% of estimated protective effect. However, 6H or 9H regimen is related with hepatotoxicity and low compliance. Four months of rifampin regimen is characterized by less hepatotoxicity and better compliance than 9H, but has few evidence of clinical efficacy. Three months of isoniazid plus rifampin was proved equivalence with 6H or 9H regimen in terms of efficacy and safety, which was recommended in NICE and WHO guidelines. The clinical efficacy of isoniazid plus rifapentine once-weekly regimen for 3 months was demonstrated recently, which is not yet introduced into South Korea.

Comparison of Interferon-γ Release Assays and the Tuberculin Skin Test for Diagnosis of Tuberculosis in Human Immunodeficiency Virus: A Systematic Review / 결핵

BACKGROUND: It remains uncertain if interferon-γ release assays (IGRAs) are superior to the tuberculin skin test (TST) for the diagnosis of active tuberculosis (TB) or latent tuberculosis infection (LTBI) in immunosuppressed populations including people with human immunodeficiency virus (HIV) infection. The purpose of this study was to systematically review the performance of IGRAs and the TST in people with HIV with active TB or LTBI in low and high prevalence TB countries. METHODS: We searched the MEDLINE database from 1966 through to January 2017 for studies that compared results of the TST with either the commercial QuantiFERON-TB Gold in Tube (QFTGT) assay or previous assay versions, the T-SPOT.TB assay or in-house IGRAs. Data were summarized by TB prevalence. Tests for concordance and differences in proportions were undertaken as appropriate. The variation in study methodology was appraised. RESULTS: Thirty-two studies including 4,856 HIV subjects met the search criteria. Fourteen studies compared the tests in subjects with LTBI in low TB prevalence settings. The QFTGT had a similar rate of reactivity to the TST, although the first-generation version of that assay was reactive more commonly. IGRAs were more frequently positive than the TST in HIV infected subjects with active TB. There was considerable study methodology and population heterogeneity, and generally low concordance between tests. Both the TST and IGRAs were affected by CD4 T-cell immunodeficiency. CONCLUSION: Our review of comparative data does not provide robust evidence to support the assertion that the IGRAs are superior to the TST when used in HIV infected subjects to diagnose either active TB or LTBI.

Diagnosis and Treatment of Latent Tuberculosis Infection: The Updated 2017 Korean Guidelines / 대한내과학회지

A small number of viable tuberculosis bacilli can reside in an individual with latent tuberculosis infection (LTBI) without obvious clinical symptoms or abnormal chest radiographs. Diagnosis and treatment of LTBI are important for tuberculosis (TB) control in public and private healthcare facilities, particularly in high-risk populations. The updated 2017 Korean guidelines for TB recommend that tuberculin skin tests, interferon-gamma release assays, or a combination of them can be used for the diagnosis of LTBI, depending on the age and immune status of the patient as well as their TB contact history. For diagnosis of LTBI, exclusion of active TB is essential, and the possibility of healed TB in those without a history of treatment for TB but at risk of its development must be considered. The treatment options for LTBI include isoniazid, rifampicin, isoniazid/rifampicin, and isoniazid/rifapentine. The benefits and risks of these agents based on the age of the patient and their hepatotoxicity must be considered when selecting the appropriate drug. Standardized diagnosis and treatment of LTBI based on the updated 2017 guidelines will contribute to the control of TB in Korea as well as to further revisions of the guidelines.

Incidence of Active Tuberculosis within One Year after Tumor Necrosis Factor Inhibitor Treatment according to Latent Tuberculosis Infection Status in Patients with Inflammatory Bowel Disease

BACKGROUND: We investigated the incidence of active tuberculosis among patients with inflammatory bowel disease (IBD) treated with tumor necrosis factor (TNF) inhibitors, with or without latent tuberculosis infection (LTBI). METHODS: The study was performed at a Korean tertiary referral center between January 2011 and June 2017. In total, 740 patients with IBD who underwent LTBI screening tests and were followed-up for ≥ 1 year after TNF inhibitor treatment initiation were enrolled. LTBI was detected on the basis of tuberculin skin test results, interferon-gamma release assay results, chest X-ray findings, and previous tuberculosis treatment history. The patients were classified into LTBI (n = 84) or non-LTBI (n = 656) group. The risk of developing tuberculosis in each group was assessed on the basis of standardized incidence ratio (SIR) and 95% confidence interval (CI) for active tuberculosis. RESULTS: Mean patient age was 33.1 years, and patients with Crohn's disease were predominant (80.7%). Within 1 year after the initiation of TNF inhibitor treatment, 1 patient in the LTBI group (1/84; 1.2%) and 7 patients in the non-LTBI group (7/656; 1.1%) developed active tuberculosis. The overall 1-year incidence of tuberculosis among the patients was significantly higher than that among the general population (SIR, 14.0; 95% CI, 7.0–28.0), and SIR was not affected by LTBI status (LTBI group: 14.5, 95% CI, 2.0–102.6; non-LTBI group: 14.0, 95% CI, 6.7–29.4). CONCLUSION: Patients with IBD undergoing TNF inhibitor treatment showed a higher 1-year incidence of tuberculosis than the general population irrespective of LTBI status.

Systemic review: agreement between the latent tuberculosis screening tests among patients with rheumatic diseases

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.

High risk of tuberculosis during infliximab therapy despite tuberculosis screening in inflammatory bowel disease patients in India

BACKGROUND/AIMS: The data on the risk of tuberculosis (TB) reactivation with infliximab (IFX) in patients with inflammatory bowel disease (IBD) from TB endemic countries, like India, is limited. The risk of TB reactivation on IFX and its predictors in patients with IBD was assessed. METHODS: This retrospective review included consecutive patients with IBD who received IFX, and were on follow-up from January 2005 to November 2017. The data was recorded on age/disease duration, indications for IFX, screening for latent tuberculosis (LTB) before IFX, response to IFX, incidence and duration when TB developed after IFX, and type of TB (pulmonary [PTB]/extra-pulmonary [EPTB]/disseminated). RESULTS: Of 69 patients (22 ulcerative colitis/47 Crohn’s disease; mean age, 35.6±14.5 years; 50.7% males; median follow-up duration after IFX, 19 months [interquartile range, 5.5–48.7 months]), primary non-response at 8 weeks and secondary loss of response at 26 and 52 weeks were seen in 14.5%, 6% and 15% patients respectively. Prior to IFX, all patients were screened for LTB, 8 (11.6%) developed active TB (disseminated, 62.5%; EPTB, 25%; PTB, 12.5%) after a median of 19 weeks (interquartile range, 14.0–84.5 weeks) of IFX. Of these 8 patients’ none had LTB, even when 7 of 8 were additionally screened with contrast-enhanced chest tomography. Though not statistically significant, more patients with Crohn’s disease than ulcerative colitis (14.9% vs. 4.5%, P=0.21), and those with past history of TB (25% vs. 9.8%, P=0.21), developed TB. Age, gender, disease duration, or extraintestinal manifestations could not predict TB reactivation. CONCLUSIONS: There is an extremely high rate of TB with IFX in Indian patients with IBD. Current screening techniques are ineffective and it is difficult to predict TB after IFX.