Tests for Latent Tuberculosis in People With ESRD: A Systematic Review

Diagnosis, Prevention, and Treatment of Infections in Kidney Transplantation

Kidney transplant often is complicated by infections in the recipient from therapy-related and patient-related risk factors. Infections in kidney transplant recipients are associated with increased morbidity, mortality, and allograft dysfunction. There is a predictable timeline after kidney transplant regarding the types of pathogens causing infections, reflecting the net state of immunosuppression. In the early post-transplant period, bacterial infections comprise two thirds of all infections, followed by viral and fungal infections. Infections occurring early after kidney transplantation are generally the result of postoperative complications. In most cases, opportunistic infections occur within 6 months after kidney transplantation. They may be caused by a new infection, a donor-derived infection, or reactivation of a latent infection. Community-acquired pneumonia, upper respiratory tract infections, urinary tract infections, and gastrointestinal infections are the most common infections in the late period after transplantation when the net immunosuppression is minimal. It is crucial to seek information on the time after transplant, reflecting the net state of immunosuppression, previous history of exposure/infections, geography, and seasonal outbreaks. It is imperative that we develop regionally specific guidelines on screening, prevention, and management of infections after kidney transplantation.

The prevalence of latent tuberculosis infection in patients with chronic kidney disease: A systematic review and meta-analysis

Objective

To estimate the prevalence of latent tuberculosis infection (LTBI) in chronic kidney disease (CKD) patients.

Methods

This study was conducted following the PRISMA guidelines. We identified, 3694 studies from the whole search, and 59 studies were included. Each study's quality was assessed using JBI checklist. We employed STATA version 17 for statistical analysis. We assessed heterogeneity using I2 heterogeneity test. Publication bias was assessed using funnel plot and Egger's test. We estimated the pooled LTBI prevalence in CKD patients along with 95%CI.

Results

The pooled prevalence of LTBI among CKD patients using data collected from 53 studies having 12,772 patients was 30.2% (95%CI; 25.5, 34.8). The pooled prevalence among pre-dialysis, hemodialysis, peritoneal dialysis, and renal transplanted patients was 17.8% (95%CI; 3.3, 32.4), 34.8% (95%CI; 29.1, 40.5), 25% (95%CI; 11, 38), and 16% (95%CI; 7, 25), respectively. The pooled prevalence of LTBI stratified by the laboratory screening methods was 25.3% (95%CI: 20.3-30.3) using TST, 28.0% (95%CI; 23.9-32.0) using QFT, and 32.6%, (95%CI: 23.7-41.5) using T-SPOT.

Conclusion

There is high prevalence of LTBI among CKD patients mainly in patients on dialysis. Thus, early diagnosis and treatment of LTBI in CKD patients should be performed to prevent active TB in CKD patients.PROSPERO registration number: CRD42022372441.

Mycobacteria in Organ Transplant Recipients

This review describes the epidemiology and risk factors of tuberculosis (TB) in solid organ transplant recipients. We discuss the pre-transplant screening for risk of TB and management of latent TB in this population. We also discuss the challenges of management of TB and other difficult to treat mycobacteria such as Mycobacterium abscessus and Mycobacterium avium complex. The drugs for the management of these infections include rifamycins which have significant drug interactions with immunosuppressants and must be monitored closely.

Solid organ transplant recipients with tuberculosis disease in California, 2010 to 2020

Using California Tuberculosis (TB) Registry data from 2010-2020, we compared the presentation and outcomes of patients with TB aged >15 years with and without solid organ transplantation (SOT). We matched to the United Network for Organ Sharing registry for 1987-2020 and the estimated time from transplantation to the diagnosis of TB, the incidence of posttransplant TB, and the probability of death and graft failure in SOT recipients with TB, compared to those without TB. From 2010-2020, there were 148 posttransplant TB cases. Patients with posttransplant TB were more likely to have extrapulmonary disease and more than twice as likely to die as TB patients without SOT (relative risk [RR], 2.2; 95% confidence interval [CI], 1.6-2.9). The median time from transplantation to TB diagnosis was 1.2 years, with the shortest time among lung transplant recipients. The incidence of TB disease among Californians with SOT was 56.0 per 100 000 person-years. The risk of death was higher among SOT recipients with posttransplant TB than those without (adjusted hazard ratio, 2.8; 95% CI, 2.0-4.1); the risk of graft failure was higher among kidney transplant recipients with posttransplant TB than those without (adjusted hazard ratio, 3.4; 95% CI, 1.7-6.9). An increased risk of death and graft failure in SOT recipients with posttransplant TB highlights the need for enhanced pretransplant TB prevention.

Prevalence of latent tuberculosis infection and its risk factors in Japanese hemodialysis patients

BACKGROUND

The majority of active tuberculosis (TB) cases develop from latent tuberculosis infection (LTBI). Since the risk of TB in hemodialysis (HD) patients is particularly high, interferon-gamma release assay (IGRA) for LTBI screening in HD patients is considered important. However, the prevalence and characteristics of LTBI in Japanese HD patients remain obscure.

METHODS

We performed an observational cross-sectional study of LTBI using IGRA QFT-3G tests in 118 HD outpatients enrolled at 3 hospitals of varying location and function.

RESULTS

Of the 118 patients, 96 were QFT negative, 7 were QFT indeterminate, 14 were QFT positive, and 1 was QFT judgment impossible. No patient had active TB. Confirmed (QFT positive) and possible (QFT positive + indeterminate) LTBI patients totaled 14 (11.9%) and 21 (17.8%), respectively. The LTBI possible group was significantly older and had a significantly higher rate of nephrosclerosis versus the QFT-negative group. The indeterminate group had a significantly longer HD period. The QFT results were not remarkably affected by other clinical data, including hospital characteristics. The possible LTBI rate increased age-dependently, with higher values from 60 years of age.

CONCLUSIONS

The prevalence of LTBI is high in Japanese HD patients, especially from the age of 60 years. Older age was a significant risk factor for LTBI, with prediction difficult using other clinical data. Extended HD may mask IGRA results. Therefore, aggressive screening for LTBI is advised in all HD patients regardless of hospital region or type, especially in patients over 60 years of age or newly commencing HD.

Hemodialysis acutely altered interferon-gamma release assay test result and immune cell profile

Patients receiving hemodialysis (HD) are at risk of TB development. IGRA-positive patients showed significant decrease in quantitative IGRA result with alterations in CD3⁺CD4⁺CD45RO⁺, NK cell, and monocyte subsets immediately upon HD procedure. Our result suggested that the timing of IGRA testing is crucial in end-stage renal disease population.

Latent tuberculosis screening before kidney transplantation in the South of Brazil

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.

Infectious disease consultation is effective in boosting vaccine coverage in patients awaiting kidney transplantation: A French prospective study

Recommended preventive strategies before kidney transplantation include screening and treatment of latent tuberculosis infection (LTBI), and updating of the recommended vaccines. We prospectively evaluated in dedicated infectious diseases consultations, from 2014 to 2018, the clinical and vaccination data of new adult kidney allograft candidates. Patients were offered an updated vaccination schedule, if appropriate, and were screened for LTBI using chest imaging and interferon gamma release assay (IGRA). Overall, 467 patients with median age of 58 [46-66] years were evaluated, of whom 302 patients (65%) were men (sex ratio 1.83), and 333 (71%) were on dialysis. Main causes of renal insufficiency were diabetes (25%) and autoimmune nephropathies (18%). The vaccination coverage was low and varied according to the different types of vaccines and patients. Vaccination or immunization rates were 24%, 6%, 54%, and 51% for tetanus-diphtheria-polio-acellular pertussis, Pneumococcus, hepatitis B, and seasonal influenza, respectively. ID consultation successfully rose patients' vaccinations coverage, in fulfillment with recommendations, in 465 (99%) patients. LTBI treatment was administered in 78 (16.7%) patients and caused drug-related adverse events in 9 (11%). A dedicated infectious disease consultation should become a critical tool for coordinating infection prevention strategies.

KDIGO Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation

The 2020 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation is intended to assist health care professionals worldwide who evaluate and manage potential candidates for deceased or living donor kidney transplantation. This guideline addresses general candidacy issues such as access to transplantation, patient demographic and health status factors, and immunological and psychosocial assessment. The roles of various risk factors and comorbid conditions governing an individual's suitability for transplantation such as adherence, tobacco use, diabetes, obesity, perioperative issues, causes of kidney failure, infections, malignancy, pulmonary disease, cardiac and peripheral arterial disease, neurologic disease, gastrointestinal and liver disease, hematologic disease, and bone and mineral disorder are also addressed. This guideline provides recommendations for evaluation of individual aspects of a candidate's profile such that each risk factor and comorbidity are considered separately. The goal is to assist the clinical team to assimilate all data relevant to an individual, consider this within their local health context, and make an overall judgment on candidacy for transplantation. The guideline development process followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Guideline recommendations are primarily based on systematic reviews of relevant studies and our assessment of the quality of that evidence, and the strengths of recommendations are provided. Limitations of the evidence are discussed with differences from previous guidelines noted and suggestions for future research are also provided.

Preventing tuberculosis in paediatric kidney transplant recipients: is there a role for BCG immunisation pre-transplantation in low tuberculosis incidence countries?

The risk of tuberculosis (TB) disease is increased in children with chronic kidney disease (CKD), even higher in stage 5 CKD/kidney failure and especially high after kidney transplantation due to immunosuppression. TB disease may follow recent primary infection, or result from reactivation of latent infection. Reactivation is more common in adults, while progression following primary infection makes up a greater proportion of disease in children. Recommendations for preventing TB disease in some low TB incidence countries have previously included offering Bacillus Calmette-Guérin (BCG) vaccine to all children listed for kidney transplant if they had not received this as part of previous national immunisation programmes. Based on the available evidence, we recommend modifying this practice, focusing instead on awareness of risk factors for TB exposure, infection and disease and the use of appropriate testing strategies to identify and treat TB infection and disease.

IL-18 and related function proteins associated with tuberculosis severity and screening for active TB among patients with non-mycobacterial community-acquired pneumonia (CAP)

Background

Differentiation of active pulmonary tuberculosis (TB) from non-mycobacterial community-acquired pneumonia (CAP) still remains a diagnostic challenge.

Objective

The study aimed to quantify the IL-18, IFN-γ, IL-18BP, IL-37, and IP-10 levels in serum and Mycobacterium tuberculosis (M.tb) antigens-stimulated blood cultures from TB or CAP patients and explore if the proteins can be a useful basis for discriminating these diseases.

Methods

In total, 124 Polish adults, including mild/moderate (M/MTB) or advanced (ATB) TB patients, and CAP patients, were enrolled in the study. The concentrations of IL-18, IL-18BP, IFN-γ, IL-37, and IP-10 in sera and M.tb-stimulated cultures were measured by ELISA.

Results

The most specific and sensitive serum proteins discriminating TB from CAP were IP-10 and IL-18BP; however, IP-10 had the highest AUC in the ROC curve for the diagnosis. Serum IP-10 and IL-18BP levels increased significantly in M/MTB or ATB groups. The IL-18BP elevation in ATB group was accompanied by an increase in IL-18. No single protein measured in M.tb-stimulated cultures differed TB from CAP patients.

Conclusions

The combined analysis of serum IL-18BP and IP-10 might be considered as an auxiliary tool in the differentiation of TB from CAP.

The Diagnosis and Treatment of Tuberculosis

BACKGROUND

Around 10 million people worldwide contract tuberculosis every year. According to the World Health Organization (WHO), approximately one-quarter of the world's population is latently infected with Mycobacterium tuberculosis. In Ger- many, the incidence of tuberculosis was in decline over several decades but rose in 2015 to 7.3 new cases per 100 000 persons. In 2018, a total of 5429 new cases were documented, corresponding to 6.5 new cases per 100 000 persons.

METHODS

This article is based on literature retrieved by a selective search in PubMed and on the authors' clinical experience.

RESULTS

Tuberculosis involves the lungs in almost 75% of patients but can generally involve any organ. In Germany, the majority of patients come from high-incidence countries. If a patient's differential diagnosis includes tuberculosis, the main tests for the detection of the pathogen in sputum and tissue samples are culture (the gold standard), microscopy, and nucleic acid amplification tests. Imaging studies are also used for diagnosis and follow-up. The standard treatment consists of a combination of isoniazid, rifampicin, ethambutol, and pyrazinamide, followed by a combination of isoniazid and rifampicin only. Liver damage is one of the more common adverse effects of this treatment, arising in 2.4% of patients. Multidrug-resistant tuberculosis, which is rare in Germany (around 100 cases per year), should be treated in special- ized centers.

CONCLUSION

Rapid diagnosis and targeted treatment are essential to prevent an unfavorable course of the disease as well as its transmission to other individuals. In patients presenting with unclear symptoms, tuberculosis should always be considered as a differential diagnosis. The diagnosis of latent tuberculosis and decision-making regarding its treatment are difficult because of the lack of specific biomarkers and of relevant data from clinical trials.

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.

The Application of T.SPOT-TB Assay for Early Diagnosis of Active Tuberculosis in Chronic Kidney Disease Patients Receiving Immunosuppressive Treatment

Background: The current study investigated the clinical application of the T-SPOT.TB assay for detecting tuberculosis (TB) infection in chronic kidney disease patients treated with immunosuppressive therapy. Methods: Clinical data from 91 patients were retrospectively analyzed. The rate of positive T-SPOT.TB results and spot numbers were compared before and after treatment. Clinical characteristics that may affect the test results were also investigated. Results: Two active TB cases were observed after immunosuppressive treatment, and eight patients with negative T-SPOT.TB results at baseline had positive results after treatment. No significant changes in spot numbers were observed for patients who were positive at baseline. Compared with pretreatment baseline, patients who received medium/high doses of corticosteroids had a greater number of T-SPOT.TB positive results (p = 0.016) and CFP-10 spots (p = 0.041) after treatment. For patients who received combination therapy with medium/high doses of corticosteroids, the T-SPOT.TB positive rate (p = 0.046) and CFP-10 spot number (p = 0.041) were increased after treatment, with no significant changes in the total number of spots or ESAT-6 spots. For those who received combination therapy with low doses of corticosteroids and those who received single immunosuppressive medication, there were no significant differences in the T-SPOT.TB positive rate, total spot number, or numbers of ESAT-6 and CFP-10 spots. Conclusion: The increase in positive T-SPOT.TB results was mainly associated with medium/high doses of glucocorticoids. The active TB cases might represent new infections. Regular monitoring using the T-SPOT.TB assay will help in the early detection of active TB.

Latent tuberculosis infection in transplant candidates: a systematic review and meta-analysis on TST and IGRA

INTRODUCTION

The diagnostic accuracy of interferon-gamma release assays (IGRAs) and the tuberculin skin test (TST) for latent tuberculosis infection (LTBI) in transplant candidates is uncertain.

METHODS

Pubmed, Embase and Cochrane library were searched to identify relevant studies. Quality of included studies was assessed with RevMan5 software (via GUADAS2 checklist). Accuracy measures of IGRAs and TST assays (sensitivity, specificity and others) were pooled with random effects model. Data were analyzed by STATA and Meta-DiSc.

RESULTS

Twenty-eight studies were selected for full review, and 16 were included in the final analysis. The pooled sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR) for TST were 46% [95% confidence interval (CI) 38-54%], 86% (95% CI 75-93%), 46.3% (95% CI 40-52), 88.7% (95% CI 87-89), 3.3 (95% CI 1.6-6.4), 0.63 (95% CI 0.52-0.77) and 5 (95% CI 2-12), respectively. For QFT-G, the pooled sensitivity, specificity, PPV, NPV, PLR, NLR, and DOR were 58% (95% CI 41-73%), 89% (95% CI 77-95%), 72.7% (95% CI 68-76), 80.6% (95% CI 78-82), 5.3 (95% CI 2.0-14.0), 0.47 (95% CI 0.30-0.75) and 11 (95% CI 3-46), respectively. Likewise, for T-SPOT.TB, the pooled sensitivity, specificity, PPV, NPV, PLR, NLR, and DOR were 55% (95% CI 40-70%), 92% (95% CI 87-95%), 60.4% (95% CI 47-72), 90.2% (95% CI 86-92), 6.7 (95% CI 4.0-11.1), 0.52 (95% CI 0.31-0.85) and 16 (95% CI 7-37), respectively.

CONCLUSIONS

IGRAs were more sensitive and specific than the TST with regard to the diagnosis of LTBI in the transplant candidates. They have added value and can be complementary to TST.

Epidemiology, detection, and management of tuberculosis among end-stage renal disease patients

Tuberculosis (TB) remains an important problem among end-stage renal disease (ESRD) patients. We reviewed the epidemiology of TB and ESRD, investigations of TB exposures in US dialysis facilities, and published guidelines to inform screening and treatment practices among US ESRD patients. Compared to TB in the general population, ESRD patients have 6-25-fold higher TB incidence rates, and mortality during treatment is 2-3-fold higher. Most TB cases among ESRD patients (~90%) occur among non-US-born persons, and an analysis of genotyping data suggests that 80% of all cases result from latent TB infection (LTBI) reactivation. Published TB contact investigations in dialysis facilities have reported cases among ESRD patients and healthcare workers. However, transmission of TB is rare: there were no reports of secondary cases of TB because of exposure to an index-case patient and there were few TB infections, which was demonstrated by low occurrence of newly positive tuberculin skin tests (12%-16%) and conversions (8%-17%) among contacts. Targeted TB education, screening, and treatment for ESRD patients at highest risk for TB exposure (eg, non-US-born persons), using interferon-gamma release assays and short course LTBI regimens (ie, isoniazid-rifapentine weekly for 12 weeks or rifampin daily for 4 months) may be an effective overall strategy for reducing TB burden in ESRD patients.

Chronic Kidney Disease

The definition and classification of chronic kidney disease (CKD) have evolved over time, but current international guidelines define this condition as decreased kidney function shown by glomerular filtration rate (GFR) of less than 60 mL/min per 1·73 m², or markers of kidney damage, or both, of at least 3 months duration, regardless of the underlying cause. Diabetes and hypertension are the main causes of CKD in all high-income and middle-income countries, and also in many low-income countries. Incidence, prevalence, and progression of CKD also vary within countries by ethnicity and social determinants of health, possibly through epigenetic influence. Many people are asymptomatic or have non-specific symptoms such as lethargy, itch, or loss of appetite. Diagnosis is commonly made after chance findings from screening tests (urinary dipstick or blood tests), or when symptoms become severe. The best available indicator of overall kidney function is GFR, which is measured either via exogenous markers (eg, DTPA, iohexol), or estimated using equations. Presence of proteinuria is associated with increased risk of progression of CKD and death. Kidney biopsy samples can show definitive evidence of CKD, through common changes such as glomerular sclerosis, tubular atrophy, and interstitial fibrosis. Complications include anaemia due to reduced production of erythropoietin by the kidney; reduced red blood cell survival and iron deficiency; and mineral bone disease caused by disturbed vitamin D, calcium, and phosphate metabolism. People with CKD are five to ten times more likely to die prematurely than they are to progress to end stage kidney disease. This increased risk of death rises exponentially as kidney function worsens and is largely attributable to death from cardiovascular disease, although cancer incidence and mortality are also increased. Health-related quality of life is substantially lower for people with CKD than for the general population, and falls as GFR declines. Interventions targeting specific symptoms, or aimed at supporting educational or lifestyle considerations, make a positive difference to people living with CKD. Inequity in access to services for this disease disproportionally affects disadvantaged populations, and health service provision to incentivise early intervention over provision of care only for advanced CKD is still evolving in many countries.

An Evidence-Based Approach to Conducting Systematic Reviews on CKD

With the growing need to integrate best evidence to inform clinical care, systematic reviews have continued to flourish. Although this type of review is integral to the synthesis of evidence-based information, systematic reviews are often conducted omitting well-established processes that ensure the validity and replicability of the study; elements of which are integral based on standards developed by the Cochrane Collaboration and the National Academy of Medicine. This review article will share best practices associated with conducting systematic reviews on the topic of CKD using an 8-step process and an evidence-based approach to retrieving and abstracting data. Optimal methods for conducting systematic review searching will be described, including development of appropriate search strategies and utilization of varied resources including databases, grey literature, primary journals, and handsearching. Processes and tools to improve research teams' coordination and efficiency, including integration of systematic review protocols and sophisticated software to streamline data management, will be investigated. In addition to recommended strategies for surveying and synthesizing CKD literature, techniques for maneuvering the complex field of Nephrology will also be explored.

A retrospective review of the two-step tuberculin skin test in dialysis patients

BACKGROUND

Reactivation of latent Mycobacterium tuberculosis infection (LTBI) is a health concern for patients on dialysis or receiving a kidney transplant, as these patients are often immunosuppressed. The most frequently used test for LTBI screening in this population is the tuberculin skin test (TST). The diagnostic accuracy (sensitivity and specificity) of the TST in a contemporary North American or Western European dialysis population is unknown.

OBJECTIVES

Our objective was to determine the diagnostic accuracy and clinical utility of the two-step TST in patients receiving dialysis.

DESIGN

This is a retrospective cohort study.

SETTING

This study is set at four tertiary dialysis units across Winnipeg, Manitoba.

PATIENTS

There are 483 chronic hemodialysis and peritoneal dialysis patients in the study.

MEASUREMENTS

The measurements are sensitivity and specificity of the TST with respect to abnormal chest X-ray.

METHODS

All patients received a two-step TST and assessment of risk factors for prior tuberculosis (TB) infection between February 2008 and December 2008. This cohort was retrospectively linked to our tuberculosis registry to ascertain if prophylaxis was received for LTBI.

RESULTS

At an induration cutoff of 5 mm, 62 (13 %) patients had a positive two-step TST. Patients with a known Bacillus Calmette-Guérin (BCG) vaccination were more likely to test positive (50 % of those with a positive TST had a BCG versus 34 % with a negative TST, p = 0.05). Using a diagnostic gold standard of an abnormal chest X-ray as a proxy for LTBI, the sensitivity of the TST was only 14 % and the specificity was 88 %. Only 8 of 62 patients with a positive TST (13 %) received prophylaxis for LTBI. None of the patients who tested negative were treated.

LIMITATIONS

There is a lack of a truly accurate gold standard for LTBI.

CONCLUSIONS

The TST has limited diagnostic and clinical utility for LTBI screening in patients on dialysis. Further research into the diagnostic accuracy of interferon-gamma release assays and a revision of LTBI screening guidelines in patients on dialysis should be considered.

Maintenance of Mycobacterium tuberculosis-specific T cell responses in End Stage Renal Disease (ESRD) and implications for diagnostic efficacy

End-stage renal disease (ESRD) patients exhibit elevated risk of tuberculosis (TB) reactivation, but current diagnostics, including the interferon gamma release assay (IGRA), exhibit poor sensitivity in ESRD. We tested 80 ESRD patients and found an 18.75% prevalence of IGRA positivity. A subset of patients was assessed for Mtb-specific expression of 44 cytokines/chemokines, and CD4+ T cell phenotype and function. Similar to non-ESRD IGRA+ individuals, Mtb-specific IFNγ, IL-1RA, IP-10, MCP-3 and IL-2 responses were identified in the ESRD IGRA+ group. 27% of the ESRD IGRA- group exhibited MCP-3 or IL-2 Mtb-specific responses, which may identify cases of latent TB infection in ESRD. Stimulation of PBMC with PPD demonstrated similar CD4+ T cell production of IFNγ, TNFα and GM-CSF by ESRD patients. The reported low sensitivity of the IGRA in ESRD cohorts is therefore unlikely to be due to poor T cell cytokine secretion, and may instead reflect defects in antigen presentation.

Tuberculosis and chronic kidney disease: an emerging global syndemic

The link between chronic kidney disease (CKD) and tuberculosis (TB) has been known for more than 40 years, but the interaction between these 2 diseases is still poorly understood. Dialysis and renal transplant patients appear to be at a higher risk of TB, in part related to immunosuppression along with socioeconomic, demographic, and comorbid factors. Meanwhile, TB screening and diagnostic test performance is suboptimal in the CKD population, and there is limited evidence to guide protocols. Given the increasing prevalence of CKD in TB endemic areas, a merging of CKD and TB epidemics could have significant public health implications, especially in low- to middle-income countries such as India and China, that are experiencing rapid increases in CKD prevalence and account for more than one-third of global TB prevalence. To begin addressing TB-CKD, a clear understanding of the relationship between these 2 conditions needs to be established, and consistent, evidence-based screening and treatment guidelines need to be developed.

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.

Demographics and prevalence of positive QuantiFERON-TB Gold In-Tube test in renal transplant candidates

BACKGROUND

Latent tuberculosis infection (LTBI) screening prior to solid organ transplantation is standard of care. QuantiFERON-TB Gold In-Tube (QFT-GIT) test is the preferred diagnostic test for renal transplant candidates (RTC). QFT-GIT reversions and the potential delay of living-donor kidney transplantation (LDKT) because of QFT-GIT positivity have not been examined previously in RTC.

METHODS

We evaluated the prevalence of positive QFT-GIT in RTC from January 1 through December 31, 2011. In addition, we examined the demographic and renal disease data differences between QFT-GIT-positive and -negative patients, changes in QFT-GIT results, and positive QFT-GIT results reverting to negative. Lastly, we evaluated if QFT-GIT-positive patients were less likely to undergo LDKT within 6 months of QFT-GIT testing.

RESULTS

In total, 722 RTC were analyzed, 16% of whom had positive QFT-GIT. The QFT-GIT-positive patients were more likely to be older and foreign-born, P < 0.0001. Haitians had the highest prevalence. Of the 119 QFT-GIT-positive patients, 25% had low/intermediate-positive results and were more likely to revert to negative, compared with patients with high-positive QFT-GIT results (50% vs. 0%, P = 0.01). A trend was seen toward fewer QFT-GIT-positive patients undergoing LDKT, compared with QFT-GIT-negative patients (0% vs. 3%, P = 0.09).

CONCLUSIONS

Our high prevalence was likely a result of the high number of foreign-born RTC. Half of our small subset of low/intermediate-positive QFT-GIT patients reverted to negative. QFT-GIT-positive patients were more likely to have their LDKT delayed.

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.

Superior Sensitivity of Ex Vivo IFN-γ Release Assays as Compared to Skin Testing in Immunocompromised Patients

Comparative assessment of the tuberculin skin testing (TST) and commercial IFN-γ release-assays (IGRAs) is hampered by the use of different antigens (tuberculin PPD in TST vs. ESAT-6/CFP-10 in IGRAs). Thus, PPD was used as a common stimulus to compare performance of the TST and three IGRAs in 72 controls, 101 hemodialysis patients and 100 renal transplant recipients. Results of the TST were compared with PPD-induced IFN-γ induction in vitro detected by ELISPOT, ELISA or a flow-cytometric FACS assay. Percentages of positive tests were significantly lower in TST (9.2%) compared to ELISA (55.3%), ELISPOT (45.3%) and FACS (44.9%, p < 0.0001). Agreement between TST and IGRAs was highest for controls (κ = 0.19-0.32) and poor in immunocompromised patients (κ = 0 for transplant patients, κ = 0.06-0.13 for hemodialysis patients). Discrepant results were largely TST negative and IGRA positive. Among IGRAs, agreement was highest between ELISPOT and FACS (κ = 0.61). Unlike TST, all IGRAs were associated with variables of mycobacterial exposure. Among IGRAs, the FACS assay was least affected by the level of immunosuppression. In conclusion, both the percentage of positive results and between-test-agreement were higher with IGRAs as compared to TST. This indicates superiority of IGRAs in detecting a PPD-specific immune response which may also apply for immunity toward Mycobacterium tuberculosis-specific antigens.

Feasibility of the interferon-gamma enzyme-linked immunospot assay in chronic renal failure patients and immunocompetent subjects: a head-to-head comparison

Diagnosis of latent Mycobacterium tuberculosis infection (LTBI) by the tuberculin skin test (TST) is hampered due to anergy and impaired sensitivity in chronic renal failure (CRF) patients. We aimed to compare the diagnostic performance of the TST with that of interferon-gamma immunospot (T-SPOT.TB®) assay in diagnosing LTBI in CRF and immunocompetent (IC) patients. A total of 74 CRF and 75 IC patients prospectively underwent the TST and T-SPOT.TB. Latent M. tuberculosis infection estimated by TST and T-SPOT.TB was detected in 69% and 43 of CRF; 52 and 35% of IC patients, respectively. The sensitivity and specificity of the T-SPOT.TB were 73 and 74% in IC, whereas 50 and 55% in CRF patients. In conclusion, the prevalence of LTBI was noteworthy in both IC and CRF patients. T-SPOT.TB was less sensitive and specific than the IC group in CRF patients. Both T-SPOT.TB and TST were not associated with the TB exposure.

American Society of Nephrology Quiz and Questionnaire 2013: transplantation

The nephrology quiz and questionnaire remains an extremely popular session for attendees of the Annual Meeting of the American Society of Nephrology. As in past years, the conference hall was overflowing with interested audience members. Topics covered by expert discussants included electrolyte and acid-base disorders, glomerular disease, ESRD/dialysis, and transplantation. Complex cases representing each of these categories along with single best answer questions were prepared by a panel of experts. Before the meeting, program directors of United States nephrology training programs answered questions through an Internet-based questionnaire. A new addition to the nephrology quiz and questionnaire was participation in the questionnaire by nephrology fellows. To review the process, members of the audience test their knowledge and judgment on a series of case-oriented questions prepared and discussed by experts. Their answers are compared in real time using audience response devices with the answers of nephrology fellows and training program directors. The correct and incorrect answers are then briefly discussed after the audience responds, and the results of the questionnaire are displayed. This article recapitulates the session and reproduces its educational value for the readers of CJASN. Enjoy the clinical cases and expert discussions.

Epidemiology of tuberculosis cases with end-stage renal disease, California, 2010

BACKGROUND/AIMS

Few studies have compared population-based tuberculosis (TB) incidence rates by end-stage renal disease (ESRD) status. No studies have compared TB genotypes by ESRD status to determine whether TB disease resulted from recent transmission or reactivation of latent TB infection (LTBI). We calculated TB incidence rates and compared demographic and clinical characteristics and genotypes among TB cases by ESRD status.

METHODS

This analysis was based on prospective surveillance for TB cases during 2010 in California. Clustered genotype was defined as ≥2 culture-positive TB cases with matching genotypes in the same county. The χ(2) or Wilcoxon rank-sum test was used to compare variables.

RESULTS

During 2010, 83 TB cases with ESRD and 2,244 cases without ESRD were reported in California; TB incidence rates were 110.3/100,000 and 6.0/100,000, respectively. ESRD case patients versus patients without ESRD were more likely to be older (median age 66 vs. 49 years; p < 0.001), foreign-born persons who had arrived in the USA >5 years before TB diagnosis (97 vs. 75%; p < 0.001) and dead at TB diagnosis (7 vs. 2%; p = 0.01). ESRD patients were less likely to have a positive tuberculin skin test (50 vs. 80%; p < 0.001), positive acid-fast bacilli sputum smears (33 vs. 53%; p = 0.01) and cavities on chest radiography (6 vs. 21%; p = 0.01). No differences in proportions of clustered TB genotypes were detected (20 vs. 23%; p = 0.54).

CONCLUSIONS

Rates of TB are 18 times higher in California's ESRD population, and TB disease likely occurred due to LTBI reactivation because few patients had clustered genotypes. Efforts to prevent TB among ESRD patients may require the use of newer diagnostic tests and promotion of LTBI treatment.

DNA-based nanosensors for next-generation clinical diagnostics via detection of enzyme activity

Specific and sensitive detection of DNA-modifying enzymes represents a cornerstone in modern medical diagnostics. Many of the currently prevalent methods are not preferred in the clinics because they rely heavily on pre-amplification or post-separation steps. This editorial highlights the potential of adopting DNA-based nanosensors for the assessment of the activities of DNA-modifying enzymes, with emphasis on the topoisomerase and tyrosyl-DNA phosphodiesterase families. By underlining the existing challenges, we expect that the DNA-nanosensors may soon be promoted to clinical diagnostics via enzyme detection.

Challenging issues in tuberculosis in solid organ transplantation

Solid organ transplant (SOT) recipients are at risk for opportunistic infections including tuberculosis. Although guidelines on the management of latent tuberculosis and active tuberculosis are available, there remain a number of clinical areas with limited guidance. We discuss challenges in the diagnosis, management, and treatment of latent and active tuberculosis in SOT candidates and recipients who reside in low-tuberculosis-prevalence areas. We discuss the diagnosis of latent tuberculosis in SOT candidates/recipients using tuberculin skin tests and interferon-γ release assays and risk stratification of SOT candidates/recipients that would identify individuals at high risk for latent tuberculosis despite negative test results. Through a careful review of posttransplant tuberculosis cases, we identify a history of treated tuberculosis in SOT recipients as a risk factor for development of posttransplant active tuberculosis. Finally, we include comparisons of recommendations by several large transplant organizations and identify areas for future research.

Heparin-binding haemagglutinin, a new tool for the detection of latent Mycobacterium tuberculosis infection in hemodialysis patients

Background

Patients with end-stage renal disease (ESRD) and latently infected with Mycobacterium tuberculosis (LTBI) are at higher risk to develop tuberculosis (TB) than healthy subjects. Interferon-gamma release assays (IGRAs) were reported to be more sensitive than tuberculin skin tests for the detection of infected individuals in dialysis patients.

Methods

On 143 dialysis patients prospectively enrolled, we compared the results from the QuantiFERON®-TB Gold assay (QFT), to those of an IGRA in response to in vitro stimulation of circulating mononuclear cells with the mycobacterial latency antigen Heparin-Binding Haemagglutinin purified from Mycobacterium bovis BCG (native HBHA, nHBHA).

Results

Seven patients had a past history of active TB and 1 had an undetermined result with both IGRAs. Among the other 135 patients, 94 had concordant results with the QFT and nHBHA-IGRA, 40.0% being negative and therefore not latently infected, and 29.6% being positive and thus LTBI. Discrepant results between these tests were found for 36 patients positive only with the nHBHA-IGRA and 5 only with the QFT.

Conclusions

The nHBHA-IGRA is more sensitive than the QFT for the detection of LTBI dialysis patients, and follow-up of the patients will allow us to define the clinical significance of discrepant results between the nHBHA-IGRA and the QFT.