Comparison of the tuberculin skin test and interferon-γ release assay for the diagnosis of latent tuberculosis infection before kidney transplantation

Screening for Latent Tuberculosis Infection in Solid Organ Transplant Recipients to Predict Active Disease: A Systematic Review and Meta-Analysis of Diagnostic Studies

BACKGROUND

This is a systematic review and meta-analysis of diagnostic test accuracy studies to assess the predictive value of both tuberculin skin test (TST) and interferon-gamma release assays (IGRA) for active tuberculosis (TB) among solid organ transplantation (SOT) recipients.

METHODS

Medline, Embase, and the CENTRAL databases were searched from 1946 until June 30, 2022. Two independent assessors extracted data from studies. Sensitivity analyses were performed to investigate the effect of studies with high or low risk of bias. Methodological quality of each publication was assessed using QUADAS-2.

RESULTS

A total of 43 studies (36 403 patients) with patients who were screened for latent TB infection (LTBI) and who underwent SOT were included: 18 were comparative and 25 noncomparative (19 TST, 6 QuantiFERON-TB Gold In-Tube [QFT-GIT]). For IGRA tests taken together, positive predictive value (PPV) and negative predictive value (NPV) were 1.2% and 99.6%, respectively. For TST, PPV was 2.13% and NPV was 95.5%. Overall, PPV is higher when TB burden is higher, regardless of test type, although still low in absolute terms. Incidence of active TB was similar between studies using LTBI prophylaxis (mean incidence 1.22%; 95% confidence interval [CI], .2179-2.221) and those not using prophylaxis (mean incidence 1.045%; 95% CI, 0.2731-1.817; P = .7717). Strengths of this study include the large number of studies available from multiple different countries; limitations include absence of gold standard for diagnosis of latent TB and low incidence of active TB.

CONCLUSIONS

We found both TST and IGRA had a low PPV and high NPV for the development of active TB posttransplant. Further studies are needed to better understand how to prevent active TB in the SOT population.

Risk factors of latent tuberculosis among chronic kidney disease with routine haemodialysis patients

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Since tuberculosis still become an important health problem in the world, especially in developing countries, CKD patients also become a high-risk population to TBC infection.

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Due to immunity impairment in CKD patients, particularly who are routinely hemodialyzed, tuberculosis is not always clinically manifested (latent).

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However, tuberculosis among CKD patients contribute to greater morbidity, quality of life and morbidity. Hence, we investigated the factors that associated with latent tuberculosis among CKD on haemodialysis patients.

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By understanding it, management of CKD patients could be more comprehensive, and the morbidity and mortality could be decreased while quality of life could be increased.

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We also provide the first documentation study of tuberculosis among CKD on haemodialysis patients in Indonesia, one of the tuberculosis endemic country.

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According our study, smoking status and HD adequacy based on URR < 73% are associated factors that contribute to LTB among CKD on HD patients.

Introduction

Methods

Results

Conclusion

Mycobacterial infections in solid organ transplant recipients

Mycobacterium tuberculosis (MTB) infection in solid organ transplant (SOT) recipients remains a major challenge for physicians and surgeons. Active tuberculosis (TB) is associated with increased morbidity and mortality in SOT recipients. MTB usually develops after transplantation in a recipient with latent TB infection (LTBI) before transplantation and may also be transmitted from the donor or acquired from the community. Therefore, screening for LTBI in donors and recipients before transplantation is very important in preventing active disease after transplantation. This review article is based on recently published data, case series, and expert recommendations. We reviewed updated information about the epidemiology, diagnosis, and treatment of latent and active TB before and after transplantation. We also reviewed recent treatments for multidrug-resistant TB.

The Relationship between Nutritional Status and Latent Tuberculosis in Routine Hemodialysis

BACKGROUND: Malnutrition in chronic kidney disease (CKD) patients undergoing hemodialysis (HD) interferes with the natural and adaptive immune response, consequently, increasing the latent tuberculosis (TB) reactivation. AIM: This study therefore aims to determine the relationship between nutritional status and latent TB in routine HD, using interferon gamma release assays (IGRA), to screen for latent TB. METHODS AND STUDY DESIGN: This study has an analytical observation cross-sectional design, and was conducted on 120 CKD-HD patients aged 18 years and above, and has been undergoing HD twice weekly for over 3 months, without malignancy, human immunodeficiency virus/acquired immunodeficiency syndrome, history of TB, or radiological evidence at the HD Unit of the Dr. Hasan Sadikin Hospital, Bandung, Indonesia, between March and May 2020, and not currently receiving immunosuppressant or TB therapy. In addition, the age, gender, history of Bacille Calmette-Guerin vaccine, CKD etiology, length of HD, HD adequacy, TB contact history, number of family members, smoking status, body mass index, albumin, malnutrition inflammation score, triceps skinfold thickness (TST), biceps skinfold thickness, suprailiac skinfold thickness (SIST), mid-upper arm circumference (MAC), and normalized protein catabolic rate between positive and negative IGRA groups, of each patient, were determined. RESULTS: In this study, all the patients met the inclusion and exclusion criteria. Based on the IGRA test, 47 patients (39.17%) tested positive, and 68 (56.67%) tested negative, while the results for the remaining 5 (4.16%) were indeterminate. The malnutrition inflammation score (MIS) score with positive IGRA 23.3 (20.0–26.7) was discovered to differ insignificantly (p value of 0.252) from the negative counterpart 20.0 (16.7–28.4). Meanwhile, in the HD adequacy assessment based on urea reduction rate, a statistically significant difference (p = 0.042) occurred between the positive 70.45 (65.70–76.61) and negative 74.15 (70.71–77.33) IGRA groups. In the smoking status, the positive and negative IGRA were discovered to differ significantly (30 (63.8% vs. 28 (41.2% p = 0.017) OR 2.521 (1.172–5.425). However, in the history of contact with TB patients, the positive and negative IGRA did not differ significantly (4.3% vs. 11.8% p = 0.160). Furthermore, there was a significant difference in TST and MAC, between MIS >5 and MIS ≤5 (p < 0.05). CONCLUSION: The assessment of nutritional status level, TST, MAC, smoking status, and adequate HD is crucial for CKD patients with routine HD, as these factors present risks of latent TB.

Agreement between the results of tuberculin skin test and Interferon-Gamma Release Assays in renal transplant candidates

Introduction:

Identification of latent tuberculosis (TB) infection is important in kidney transplant candidates. Due to the absence of a gold standard, both tuberculin skin test (TST) and interferon-gamma release assays (IGRA) are used to screen patients. The aim of this study was to evaluate the agreement of these two tests in patients undergoing renal transplantation.

Materials and Methods:

Two hundred kidney transplant candidates at a referral center in 2014–2017 were included in this study. TST and Quantiferon-Gold (QFT-G) tests were performed for all patients before transplantation. In case of a positive result in any of the tests, patients were administered a 9-month prophylaxis treatment using isoniazid. Cohen's kappa coefficient (k) test was used to determine the agreement between the two tests.

Results:

The mean age of patients was 40.72 ± 18.33. Nine (4.5%) patients had positive TST and 16 (8%) had positive IGRA. Concordance of the two tests was evaluated as medium (κ = 0.44 and P < 0.001). No association was found between the underlying causes of renal failure and skin test positive or IGRA. The tests showed a poor agreement among diabetics, candidates of re-transplantation, and those who were on dialysis for longer than a year (κ < 0.20).

Conclusion:

TST or IGRA can be used to screen TB in kidney transplant candidates with a moderate agreement. However, we suggest using both TST and QFT-G in diabetics, re-transplant candidates, and those on dialysis for >1 year.

High prevalence of latent tuberculosis in hematopoietic stem cell transplant recipients: A First Report

TB is an increasing health problem, and patients undergoing HSCT are more prone to develop tuberculosis. The aim of our study was to evaluate prevalence of latent tuberculosis in HSCT recipients. In this study, 84 patients (2 months to 18 years) who were candidates for HSCT at the referral hospital of Tehran Children's Medical Center were enrolled. The TST and the QFT-GIT test were performed in all 84 patients, simultaneously. LTBI was considered when one of the tests was positive. Overall, the prevalence of LTBI in HSCT recipients in our study was 12% (10 cases). TST induration ≥5 mm was seen in only three patients (3.5%). Eight patients (9.5%) had a positive result for IGRA test, and 11 of them (13%) had indeterminate QFT-GIT result. The agreement between the TST results (induration size ≥5 mm) and the QFT-GIT results was poor (kappa = 0.14). In conclusion, there was a high rate of discordance between TST and IGRA results with many more positive QFT-GIT tests. However, more studies are needed in this population to determine whether this discordance reflects true infection.

The usefulness of quantitative interferon-gamma releasing assay response for predicting active tuberculosis in kidney transplant recipients: A quasi-experimental study

OBJECTIVES

We evaluated the effectiveness of IGRA-based isoniazid (INH) treatment with the diagnostic value of quantitative IGRA titer for post-transplant tuberculosis (TB) in kidney transplant (KT) recipients.

METHODS

All adult KT recipients were enrolled from January 2014 to December 2017. The development of TB after KT was observed, stratified by quantitative IGRA results as well as by IGRA results with/without INH treatment.

RESULTS

Of 1150 KT recipients, 322 (28%) revealed positive IGRA results (≥0.35 IU/mL) and 12 (1.0%) developed TB. Seven (3.2%) of 217 patients with positive IGRA without INH developed TB, whereas none of 105 patients with positive IGRA with INH developed TB (rate difference -1616 per 100,000 person-years, P = 0.016) and 5 (0.6%) of 828 patients with negative or indeterminate IGRA developed TB (rate difference -1388 per 100,000 person-years, P<0.001). Among the 217 positive IGRA patients without INH, 6 (6.4%) of 94 patients who had positive IGRA titer>2.96 IU/mL developed TB, whereas one (0.8%) of 123 patients who had positive IGRA titer≤2.96 IU/mL developed TB (rate difference 2964 per 100,000 person-years, P = 0.017).

CONCLUSIONS

IGRA-based INH treatment with risk stratification by quantitative IGRA results appears to be effective to prevent the development of TB in KT recipients.

Tests for latent tuberculosis in candidates for solid organ transplantation: A systematic review and meta-analysis

Reactivation of latent tuberculosis following solid organ transplantation has serious consequences for the recipient. The most useful diagnostic test for latent TB is not clear. We conducted a systematic review and meta-analysis to assess the relative test performance of interferon gamma release assays (IGRAs) and the tuberculin skin test (TST) in people undergoing solid organ transplantation. The clinical or radiological risk factors were used as the proxy reference standard. Test performance was expressed as an odd ratio (OR). We identified 24 studies (N = 7811), 12 studies compared IGRAs with TST directly, nine studies evaluated only TST and three studies only IGRAs. Direct comparison between tests and clinical risk factors indicated both tests were strongly associated with the presence of clinical risk factors for TB (TST: OR 3.17; 95%CI 1.55-6.48, IGRA: OR 2.78; 95%CI 1.55-5.01), and radiological evidence of past TB (TST: OR 3.26; 95%CI 1.85-5.73, IGRA: OR 3.85; 95%CI 2.16-6.86). Relative comparison indicated IGRAs positivity was more strongly associated with presence of radiological evidence of TB than TST (relative OR: 3.24; 95%CI 1.10-9.56). While there is no strong evidence in supporting use of IGRAs over TST for diagnosing latent TB, IGRAs positivity is more associated with the presence of radiological evidence of previous TB.

Prevention and Management of Tuberculosis in Solid Organ Transplant Recipients

Solid organ transplant recipients are at an increased risk of tuberculosis and transplant candidates should be screened early in their evaluation with a detailed history, tuberculin skin test or tuberculosis interferon-gamma release assay, and chest radiograph. For latent tuberculosis treatment, isoniazid and rifamycin-based regimens have advantages and disadvantages; treatment decisions should be customized. Tuberculosis after solid organ transplantation generally occurs after months or years; early infections should raise the possibility of donor-derived infections. Tuberculosis diagnosis and treatment in solid organ transplant recipients may be complicated by protean manifestations, drug interactions, and adverse drug reactions.

Prevalence of latent tuberculosis infection in transplant candidates: A systematic review and meta-analysis

INTRODUCTION

Tuberculosis (TB) is considered as a serious complication for organ transplant recipients; therefore, the detection and appropriate treatment of latent infection are recommended for preventing active TB infections in the future. The objective of this review is to conduct a systematic review and meta-analysis of studies assessing the prevalence of latent TB infection (LTBI) in transplant candidates.

METHODS

Electronic databases, including MEDLINE (via PubMed), SCOPUS were searched until 30 June 2017. The prevalence of LTBI was estimated using the random effects meta-analysis. Heterogeneity was evaluated by subgroup analysis. Data were analyzed by STATA version 14.

RESULTS

The pooled prevalence of LTBI based on tuberculin skin test (TST) in different transplant types was as follows: liver 24% (14%-33%, 95% CI), lung 22% (18%-26%), renal 21% (16%-27%, 95% CI) and hematopoietic stem cell transplantation (HCT) 14% (9%-19%). The prevalence of LTBI based on Interferon Gamma Release Assay (IGRA) tests in renal transplant candidates was 31% (95% CI; 25-37%), which was much higher than the prevalence of LTBI in liver transplant candidates (25%, 95% CI; 17-33%) and HCT transplant candidates (13%, 95% CI; 10-16%) and there was statistically significant differences between them. The pooled prevalence of indeterminate results based on IGRAs test in different transplant types was as follows: renal 6% (4%-8%, 95% CI) and liver 12% (2%-21%, 95% CI). Subgroup analysis revealed that there were statistically significant differences between the overall prevalence of indeterminate results by using IGRA tests in liver transplant candidates (12%, 95% CI; 2-21%) and renal transplant candidates (6%, 95% CI; 4-8%). The pooled prevalence of post-transplant TB was 2% (1%-2%, 95% CI) and its occurrence was more common in renal recipients (4% (2%-7%, 95% CI)) than in the liver transplant patients (1% (0%-2%, 95% CI)). The prevalence of LTBI in the subgroup (i.e. the patients' mean age was <50 years) was significantly higher than the prevalence of LTBI by using TST/IGRAs in the other subgroup (i.e. the patients' mean age was ≥50 years).

CONCLUSION

Our study suggests fair overall agreement between IGRAs and TST in patients requiring liver and HCT transplantation, while a superiority of IGRAs over TST in patients requiring renal transplantation was seen.

Accurate diagnosis of latent tuberculosis in children, people who are immunocompromised or at risk from immunosuppression and recent arrivals from countries with a high incidence of tuberculosis: systematic review and economic evaluation

BACKGROUND

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB) [(Zopf 1883) Lehmann and Neumann 1896], is a major cause of morbidity and mortality. Nearly one-third of the world's population is infected with MTB; TB has an annual incidence of 9 million new cases and each year causes 2 million deaths worldwide.

OBJECTIVES

To investigate the clinical effectiveness and cost-effectiveness of screening tests [interferon-gamma release assays (IGRAs) and tuberculin skin tests (TSTs)] in latent tuberculosis infection (LTBI) diagnosis to support National Institute for Health and Care Excellence (NICE) guideline development for three population groups: children, immunocompromised people and those who have recently arrived in the UK from high-incidence countries. All of these groups are at higher risk of progression from LTBI to active TB.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE, The Cochrane Library and Current Controlled Trials were searched from December 2009 up to December 2014.

REVIEW METHODS

English-language studies evaluating the comparative effectiveness of commercially available tests used for identifying LTBI in children, immunocompromised people and recent arrivals to the UK were eligible. Interventions were IGRAs [QuantiFERON(®)-TB Gold (QFT-G), QuantiFERON(®)-TB Gold-In-Tube (QFT-GIT) (Cellestis/Qiagen, Carnegie, VA, Australia) and T-SPOT.TB (Oxford Immunotec, Abingdon, UK)]. The comparator was TST 5 mm or 10 mm alone or with an IGRA. Two independent reviewers screened all identified records and undertook a quality assessment and data synthesis. A de novo model, structured in two stages, was developed to compare the cost-effectiveness of diagnostic strategies.

RESULTS

In total, 6687 records were screened, of which 53 unique studies were included (a further 37 studies were identified from a previous NICE guideline). The majority of the included studies compared the strength of association for the QFT-GIT/G IGRA with the TST (5 mm or 10 mm) in relation to the incidence of active TB or previous TB exposure. Ten studies reported evidence on decision-analytic models to determine the cost-effectiveness of IGRAs compared with the TST for LTBI diagnosis. In children, TST (≥ 5 mm) negative followed by QFT-GIT was the most cost-effective strategy, with an incremental cost-effectiveness ratio (ICER) of £18,900 per quality-adjusted life-year (QALY) gained. In immunocompromised people, QFT-GIT negative followed by the TST (≥ 5 mm) was the most cost-effective strategy, with an ICER of approximately £18,700 per QALY gained. In those recently arrived from high TB incidence countries, the TST (≥ 5 mm) alone was less costly and more effective than TST (≥ 5 mm) positive followed by QFT-GIT or T-SPOT.TB or QFT-GIT alone.

LIMITATIONS

The limitations and scarcity of the evidence, variation in the exposure-based definitions of LTBI and heterogeneity in IGRA performance relative to TST limit the applicability of the review findings.

CONCLUSIONS

Given the current evidence, TST (≥ 5 mm) negative followed by QFT-GIT for children, QFT-GIT negative followed by TST (≥ 5 mm) for the immunocompromised population and TST (≥ 5 mm) for recent arrivals were the most cost-effective strategies for diagnosing LTBI that progresses to active TB. These results should be interpreted with caution given the limitations identified. The evidence available is limited and more high-quality research in this area is needed including studies on the inconsistent performance of tests in high-compared with low-incidence TB settings; the prospective assessment of progression to active TB for those at high risk; the relative benefits of two-compared with one-step testing with different tests; and improved classification of people at high and low risk for LTBI.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014009033.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Tuberculosis and Transplantation

Mycobacterium tuberculosis is a major opportunistic pathogen in transplant recipients. Compared to that in the general population, the frequency of tuberculosis (TB) is 10 to 40 times higher in hematopoietic stem cell transplant (HSCT) recipients and 20 to 74 times higher in solid-organ transplant (SOT) recipients. Transplant recipients with TB are also more likely to develop disseminated disease, have longer time to definitive diagnosis, require more invasive diagnostic procedures, and experience greater anti-TB treatment-related toxicity than the general population. Specific risk factors for TB in SOT recipients include previous exposure to M. tuberculosis (positive tuberculin skin tests and/or residual TB lesions in pretransplant chest X ray) and the intensity of immunosuppression (use of antilymphocyte antibodies, type of basal immunosuppression, and intensification of immunosuppressive therapy for allograft rejection). Risk factors in HSCT recipients are allogeneic transplantation from an unrelated donor; chronic graft-versus-host disease treated with corticosteroids; unrelated or mismatched allograft; pretransplant conditioning using total body irradiation, busulfan, or cyclophosphamide; and type and stage of primary hematological disorder. Transplant recipients with evidence of prior exposure to M. tuberculosis should receive treatment appropriate for latent TB infection. Optimal management of active TB disease is particularly challenging due to significant drug interactions between the anti-TB agents and the immunosuppressive therapy. In this chapter, we address the epidemiology, clinical presentation, diagnostic considerations, and management strategies for TB in SOT and HSCT recipients.

Latent Tuberculosis Infection Testing Practices in Long-Term Care Facilities, Boston, Massachusetts

OBJECTIVES

To describe latent tuberculosis infection (LTBI) testing practices in long-term care facilities (LTCFs).

DESIGN

Retrospective cohort study.

SETTING

Three Boston-area LTCFs.

PARTICIPANTS

Residents admitted between January 1 and December 31, 2011.

MEASUREMENTS

Resident demographic characteristics, comorbidities, LTCF stay, and LTBI testing and treatment.

RESULTS

Data for 291 LTCF residents admitted in 2011 were reviewed. Of the 257 without a history of LTBI and with documentation of testing, 162 (63%) were tested; 114 of 186 (61%) with a stay less than 90 days and 48 of 71 (68%) with a stay of 90 days or longer were tested. Of 196 residents with data on prior LTBI testing, 39 (19.9%) had LTBI; 12 of these (30.8%) were diagnosed at the LTCF. Hispanic participants were more likely than black participants to undergo LTBI testing (adjusted odds ratio (aOR) = 2.4, P = .003). Having a length of stay of less than 90 days (aOR = 0.7, P < .001) and history of illicit drug use (aOR = 0.7, P < .001) were associated with lower odds of LTBI testing.

CONCLUSION

One-fifth of LTCF residents had LTBI, but testing was not always performed. The high prevalence of LTBI in older adults combined with the risk of an outbreak if a case of tuberculosis occurs in a LTCF make LTBI testing and treatment an important prevention opportunity. The importance of LTBI testing in LTCFs needs to be reinforced.

Comparison of QuantiFERON-TB Gold In-Tube (QFT-GIT) and tuberculin skin test (TST) for diagnosis of latent tuberculosis in haemodialysis (HD) patients: a meta-analysis of κ estimates

Diagnosis of latent tuberculosis infection (LTBI) is a concern in haemodialysis (HD) patients. Many studies have compared QuantiFERON-TB Gold In-Tube (QFT-GIT) and tuberculin skin test (TST) for detecting LTBI and reported the κ statistic of agreement between QFT-GIT and TST in HD patients. The present study aimed to systematically review this literature and conduct meta-analysis of individual studies that estimated the κ between QFT-GIT with TST among HD patients. All relevant published studies that were available as full-text were obtained by searching Medline (1950), Web of Sciences (1945), Scopus (1973) through May 2016. The κ was re-estimated from the individual studies and pooled using random effect meta-analysis. Subgroup analysis and meta-regression were applied to evaluate the effect of Bacillus Calmette-Guérin (BCG) vaccination, TST cut-off points, quality of studies, sample size and age on variation of κ estimate. Eight studies involving 901 HD patients were included in meta-analysis. The pooled κ estimate was 0·28 (I 2 = 18·4%, P = 0·239, 95% confidence intervals 0·22-0·34). The discordance of TST-/QFT-GIT+ was more than TST+/QFT-GIT-. History of BCG vaccination, TST cut-off points and age are related to variation of κ estimates. TST and QFT-GIT are not comparable in detecting LTBI in HD patients. The higher TST-/QFT-GIT+ ratio compared with TST+/QFT-GIT- ratio, may indicate the superiority of QFT-GIT over TST for detection LTBI in HD patients.

Mycobacteria

The immunocompromised host is at increased risk of Mycobacterium tuberculosis complex and nontuberculous mycobacteria infection. Although Mycobacterium tuberculosis complex is a significant mycobacterial pathogen, nontuberculous mycobacteria causes substantial disease in those with suppressed immune responses. Mycobacterial infections can cause significant morbidity and mortality in this patient population, and rapid identification and susceptibility testing of the mycobacterial species is paramount to patient management and outcomes. Mycobacterial diagnostics has undergone some significant advances in the last two decades with immunodiagnostics (interferon gamma release assay), microscopy (light-emitting diode), culture (automated broth-based systems), identification (direct PCR, sequencing and matrix-assisted laser-desorption ionization–time of flight mass spectrometry) and susceptibility testing (molecular detection of drug resistance from direct specimens or positive cultures). Employing the most rapid and sensitive methods in the mycobacterial laboratory will have a tremendous impact on patient care and, in the case of Mycobacterium tuberculosis complex, in the control of tuberculosis.

Comparison of interferon gamma release assay & tuberculin skin tests for diagnosis of latent tuberculosis in patients on maintenance haemodialysis

Background & objectives:

Tuberculosis (TB) is a common infection in patients on haemodialysis. There is a definite role of treatment of latent TB (LTB) in these patients. However, diagnosis of LTB in these patients by tuberculin skin test (TST) is unreliable. There is suggestion that interferon gamma release assay (IGRA) will be more reliable test for diagnosis of LTB in this setting. Thus, we evaluated value of IGRA and TST for the diagnosis of LTB in patients on dialysis in an Indian setting.

Methods:

Patients with end stage kidney disease on dialysis were included. Patients with active TB were excluded. Each patient was subjected to TST (induration of ≥10 mm was taken as positive) and QuantiFERON TB Gold In-Tube test (QFT-GIT) for diagnosis of LTB.

Results:

A total of 185 patients were included; 129 (69.7%) were males and mean age was 36.7 ± 12.3 yr. Past history of TB was present in 18 (9.7%) patients. One hundred and thirty four (72.4%) patients had scar of BCG vaccination. QFT-GIT test was positive in 66 (36%), TST in 32 (17%) and both in 13 (7%) patients. Of the 66 patients positive with QFT-GIT, only 13 (19.6%) were positive for TST. Of the 32 patients positive with TST, only 13 (40.6%) were positive with QFT-GIT; 100 (54%) patients were negative for both the tests. Overall, 85 (45.9%) patients were positive for either of the two tests. Poor agreement was shown between the two methods. On logistic regression analysis, odds of QFT-GIT to be positive in patients with BCG vaccination was 1.23 and with history of TB 0.99, both being insignificant. odds of tuberculin skin test to be positive in patients with BCG vaccination was 1.04 and with history of TB 0.99, both again being insignificant.

Interpretation & conclusions:

Our findings showed that more number of patients (36%) on haemodialysis were positive for QuantiFERON Gold In-Tube test as compared to TST (17%). There was poor agreement between the two tests. No significant effect of BCG vaccination and history of TB in past was observed on both tests.

The complexity of diagnosing latent tuberculosis infection in older adults in long-term care facilities

OBJECTIVES

In the USA, tuberculosis disease rates are highest in older adults. Diagnostic testing for latent tuberculosis infection (LTBI) has not been evaluated carefully in this group. The aim of this study was to define the relationship between tuberculin skin test (TST) results, T-SPOT.TB results, and T-cell responses to Mycobacterium tuberculosis antigens.

METHODS

Long-term care facility residents with known prior TST results (positive or negative) were retested with TSTs and T-SPOT.TB. Prior exposure to M. tuberculosis was assessed by quantifying T-cell activation to mycobacterial antigens in vitro.

RESULTS

The median age of the 37 participants was 77 years (range 57-98 years). Among 18 participants with a prior positive TST, three (16.7%) had a negative TST when retested (TST reversion); two had a negative T-SPOT.TB. Of the 15 who were historically and currently TST-positive, four (26.7%) had a negative T-SPOT.TB and one (6.7%) had a borderline result. Percentages of CD4+ T-cells responding to mycobacterial antigens were higher in participants with positive TST and T-SPOT.TB (18.2%) compared to those with a positive TST but negative T-SPOT.TB (6.4%, p=0.16) and negative TST and T-SPOT.TB (5.9%, p<0.001).

CONCLUSIONS

LTBI testing in older adults is complicated by TST reversion and TST-positive/T-SPOT.TB-negative discordance, which may reflect clearance of infection or waning immunity.

Detecting latent tuberculosis in compromised patients

PURPOSE OF REVIEW

The detection of latent tuberculosis infection (LTBI) in different categories of compromised patients is reviewed with focus on the role of strategies incorporating immunodiagnostic tests and analysis of epidemiological and clinical risk factors.

RECENT FINDINGS

The development of active tuberculosis (TB) is increased in compromised patients and is closely related to determinants for disease reactivation or newly acquired TB infection. A targeted detection of LTBI in these high-risk groups should be performed especially if preventive treatment is planned. The performance of immunodiagnostic tests is highly variable among different groups of immunocompromised individuals. Findings of cross-sectional studies indicate a better diagnostic accuracy of interferon-γ release assays over the tuberculin skin test. The critical issue is that in low-incidence countries, the positive and negative predictive values of any of immunodiagnostic tests were very poor. A targeted testing process involving analysis of TB risk factors increases the predictive positive values of immunodiagnostic tests and may improve LTBI detection.

SUMMARY

The LTBI detection in immunocompromised patients is a challenge. The development of new immunological biomarkers and integrated clinical and epidemiological strategies are needed to identify LTBI in compromised individuals and to plan preventive chemotherapies in those at risk of developing active TB.

Mycobacterial infections in solid organ transplant recipients

Mycobacterial infections represent a growing challenge for solid organ transplant recipients (SOT). The adverse effects of tuberculosis (TB) therapy present a major difficulty, due to the interactions with immunosuppressive drugs and direct drug toxicity. While TB may be donor-transmitted or community-acquired, it usually develops at a latent infection site in the recipient. Pre-transplant prevention efforts will improve transplant outcomes and avoid the complications associated with post-transplant diagnosis and treatment. The present review and consensus manuscript is based on the updated published information and expert recommendations. The current data about epidemiology, diagnosis, new regimens for the treatment of latent TB infection (LTBI), the experience with rifamycins for the treatment of active TB in the post-transplant period and the experience with isoniazid for LTBI in the liver transplant population, are also reviewed. We attempt to provide useful recommendations for each transplant period and problem concerning mycobacterial infections in SOT recipients.

Transplantation in the tropics: lessons on prevention and management of tropical infectious diseases

Tropical infectious diseases (IDs) remain a rare complication in transplant recipients even in tropical settings, but this topic has become increasingly important during the last decade due to multiple factors. Interestingly, non-tropical countries report most of the experiences with tropical diseases. The reported experience from non-endemic regions, however, does not always reflect the experience of endemic areas. Most of the guidelines and recommendations in the literature may not be applicable in tropical settings due to logistical difficulties, cost, and lack of proven benefit. In addition, certain post-transplant prevention measures, as prophylaxis and reducing exposure risk, are not feasible. Nonetheless, risk assessment and post-transplant management of tropical IDs in tropical areas should not be neglected, and clinicians need to have a higher clinical awareness for tropical ID occurring in this population. Herein, we review the more significant tropical ID in transplant patients, focusing on relevant experience reported by tropical settings.

Diagnosis and treatment of latent tuberculosis infection

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 for LTBI are important for tuberculosis (TB) control in public and private health, especially in high-risk populations. The updated 2014 Korean guidelines for TB recommend that tuberculin skin tests, interferon-gamma release assays, or a combination of the two can be used for LTBI diagnosis according to age and immune status of the host as well as TB contact history. The regimens for LTBI treatment include isoniazid, rifampicin, or isoniazid/rifampicin. However, results of drug susceptibility test from the index case must be considered in selecting the appropriate drug for recent contacts. Standardized LTBI diagnosis and treatment based on the new 2014 guidelines will contribute to the effective TB control in Korea as well as to the establishment of updated guidelines.

Gender disparities in latent tuberculosis infection in high-risk individuals: a cross-sectional study

Male predominance in active tuberculosis (TB) is widely-reported globally. Gender inequalities in socio-cultural status are frequently regarded as contributing factors for disparities in sex in active TB. The disparities of sex in the prevalence of latent TB infection (LTBI) are less frequently investigated and deserve clarification. In this cross-sectional study conducted in a TB endemic area, we enrolled patients at high-risk for LTBI and progression from LTBI to active TB from 2011 to 2012. Diagnosis of LTBI was made by QuantiFERON-TB Gold In-Tube (QFT-GIT). Differences in sex in terms of prevalence of LTBI and clinical predictors for LTBI were investigated. Associations among age, smoking status, and sex disparities in LTBI were also analyzed. A total of 1018 high-risk individuals with definite QFT-GIT results were included for analysis, including 534 males and 484 females. The proportion of LTBI was significantly higher in males than in females (32.6% vs. 25.2%, p = 0.010). Differences in the proportion of LTBI between sexes were most prominent in older patients (age ≥ 55 years). In multivariate analysis, independent clinical factors associated with LTBI were age (p = 0.014), smoking (p = 0.048), and fibro-calcified lesions on chest radiogram (p = 0.009). Male sex was not an independent factor for LTBI (p = 0.88). When stratifying patients according to the smoking status, the proportion of LTBI remained comparable between sexes among smokers and non-smokers. In conclusion, although the proportion of LTBI is higher in men, there is no significant disparity in terms of sex in LTBI among high-risk individuals after adjusting for age, smoking status, and other clinical factors.

Diagnosis of latent tuberculosis infection before initiation of anti-tumor necrosis factor therapy using both tuberculin skin test and QuantiFERON-TB Gold In Tube assay

BACKGROUND

Reactivation of latent tuberculosis infection (LTBI) is an important complication in patients treated with tumor necrosis factor-alpha (TNF-α) blocking agents. However, the best method for LTBI detection before initiation of anti-TNF therapy remains to be determined.

METHODS

From January 2010 to August 2013, anti-TNF therapy was initiated in 426 patients with immune-mediated inflammatory diseases (IMIDs). Tuberculin skin test (TST) and Quantiferon-TB Gold In Tube (QFT-GIT) assay were performed before starting anti-TNF treatment. LTBI was defined as a positive TST (induration ≥ 10 mm) or as a positive QFT-GIT result. Patients were followed up until December 2013.

RESULTS

The positive TST and QFT-GIT rates were 22.3% (95/426) and 16.0% (68/426), respectively, yielding a total of 27.0% (115/426) of positive LTBI results. LTBI treatment was initiated in 25.1% (107/426) and was completed in 100% (107/107) of patients. During a median 294 days of follow-up, active TB occurred in 1.4% (6/426) of the patients with negative TST and QFT-GIT results at baseline.

CONCLUSION

The either test positive strategy, using both TST and QFT-GIT assay, is acceptable for LTBI screening before commencing anti-TNF therapy in patients with IMIDs.

Impact of cytotoxic and targeted antineoplastic drugs on the validity of the mitogen-induced interferon-gamma release assay for latent tuberculosis infection: results of a prospective trial at a comprehensive cancer center

Abstract The T-SPOT.TB test (TS.TB), an interferon-gamma (IFN-γ) release assay (IGRA), is superior in diagnosing latent tuberculosis infection compared with the conventional tuberculin skin test (TST). However, whether cytotoxic chemotherapy and treatment with new-generation antineoplastic monoclonal antibodies affects the TS.TB is not certain. We evaluated the feasibility of using the TS.TB in this population. Sixteen cancer patients at high risk for tuberculosis exposure were prospectively evaluated with the TST and TS.TB. Blood samples were obtained 7.5 ± 89.3 days after the most recent cycle of antineoplastic therapy. Six patients (38%) were febrile within 24 h of blood sampling; high-dose corticosteroid therapy and profound treatment-induced neutropenia were present in 1 patient each. In all patients, TS.TB showed no evidence of latent tuberculosis infection. A robust mitogen-induced IFN-γ response was seen in samples from 14 patients (88%) despite therapy with high-dose corticosteroids, cyclophosphamide, fludarabine, gemtuzumab ozogamicin, and alemtuzumab. The presence of fever or profound neutropenia did not negatively impact mitogen response by peripheral lymphocytes. The 2 patients whose peripheral blood lymphocytes (> 500 cells/ml) failed to generate a cytokine response to ex vivo mitogen stimulation had refractory advanced cancer. Unlike the TST, a negative TS.TB provided interpretable results even in cancer patients undergoing new-generation immunosuppressive therapy.

Tuberculin skin test and boosted reactions among newly employed healthcare workers: an observational study

Objective

To evaluate the prevalence of and factors associated with latent tuberculosis infection (LTBI) based on the tuberculin skin test (TST) and to estimate the boosted reaction rate among newly employed healthcare workers (HCWs).

Design

Newly employed HCWs between January 2010 and July 2012 at Severance Hospital in South Korea were enrolled in this study. A one-step TST was conducted before October 2011, and a two-step TST after October 2011.

Results

Of 2132 participants, 778 (36.5%) had positive TST results. Being older (odds ratio [OR] 1.10, 95% confidence interval [CI] 1.06–1.13, P<0.001), male (OR 1.78, 95% CI 1.21–2.62, P = 0.003), rejoining the hospital workforce (OR 1.58, 95% CI 1.04–2.40, P = 0.032), and having a previous history of tuberculosis (TB) (OR 18.21, 95% CI 2.15–154.10, P = 0.008) during the one-step period, and being older (OR 1.15, 95% CI 1.10–1.21, P<0.001) during the two-step period were significantly associated with a positive TST. A two-step TST was performed in 556 HCWs, and a boosted reaction was observed in 79 (14.2%). The induration size on the first TST (5–9-mm group) was the only factor associated with a boosted reaction on the second TST.

Conclusions

The prevalence of LTBI based on the TST among newly employed HCWs was high. The boosted reaction rate on two-step TST was not low; therefore, the use of two-step TST may be necessary for regular monitoring in countries with an intermediate TB burden and a high rate of Bacillus Calmette-Guérin vaccination.

Prevention of tuberculosis in older adults in the United States: obstacles and opportunities

BACKGROUND

Persons ≥65 are a growing proportion of the US population and are at increased risk for tuberculosis disease. The objective of the study was to examine rates and identify risk factors for tuberculosis among older adults in the United States.

METHODS

Average rates and rate ratios for tuberculosis by age group, race/ethnicity, country of birth, calendar year, and long-term care facility residence were calculated using Centers for Disease Control and Prevention tuberculosis case reports and Census Bureau data.

RESULTS

Older adults accounted for 21.9% of tuberculosis cases in the United States between 1993 and 2008. Average yearly tuberculosis rates over sixteen years were 10.9 per 100 000 (95% confidence interval [CI], 10.8-11.0) in older adults compared with 7.3 per 100 000 (95% CI, 7.3-7.4) in persons aged 21-64 (rate ratio [RR], 1.5; 95% CI, 1.5-1.5). Among older adults, tuberculosis rates increased with age from 9.6 per 100 000 in persons aged 65-74 to 14.2 per 100 000 in persons aged ≥85 years. Older persons at higher risk for tuberculosis include men (RR, 2.1; 95% CI, 2.1-2.2), American Indians/Alaska Natives (RR 3.6; 95% CI, 3.4-3.9), those in long-term care facilities (RR 2.3; 95% CI, 2.2-2.3), and the foreign-born (RR 5.1; 95% CI, 5.0-5.2).

CONCLUSIONS

Elimination of tuberculosis in the United States will require addressing the substantial burden of disease among older persons, especially men, non-whites, long-term care facility residents, and foreign-born persons. Use of interferon-γ release assay testing may help prioritize persons with greatest need for treatment of latent tuberculosis infection, as new shorter and less toxic regimens make latent tuberculosis treatment in older adults more attractive.