Risk of tuberculosis after lung transplantation: the value of pretransplant chest computed tomography and the impact of mTOR inhibitors and azathioprine use

CT in the detection of latent tuberculosis: a systematic review

AIM

To evaluate the use of computed tomography (CT) and low-dose CT in the detection of latent tuberculosis (TB).

MATERIALS AND METHODS

A systematic search of literature in adherence with the PRISMA guidelines was carried out. Quality assessment of the included studies was conducted.

RESULTS

The search strategy identified a total of 4,621 studies. Sixteen studies were considered eligible and included in the review. There was high heterogeneity among all studies. CT was identified as much more sensitive for the detection of latent TB in all studies despite chest radiography often being recommended in guidelines to assess patients for latent TB. Low-dose CT showed promising results in four of the studies; however, these results were limited due to small sample sizes.

CONCLUSION

CT is much superior to chest radiography consistently identifying additional cases of latent TB. There are limited high-quality publications available using low-dose CT but findings thus far suggest low-dose CT could be used as an alternative to standard-dose CT for the detection of latent TB. It is recommended that a randomised controlled trial investigating low-dose CT should be carried out.

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.

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.

Thiopurines are an independent risk factor for active tuberculosis in inflammatory bowel disease patients

The use of thiopurines is an independent risk factor for active tuberculosis in patients with inflammatory bowel disease.

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.

Evaluation of Everolimus Activity against Mycobacterium tuberculosis Using In Vitro Models of Infection

Even though Everolimus has been investigated in a phase II randomized trial as a host-directed therapy (HDT) to treat tuberculosis (TB), an oncological patient treated with Everolimus for a neuroendocrine pancreatic neoplasia developed active TB twice and a non-tuberculous mycobacterial (NTM) infection in a year and a half time span. To investigate this interesting case, we isolated and genotypically characterized the Mycobacterium tuberculosis (Mtb) clinical strain from the patient and tested the effect of Everolimus on its viability in an axenic culture and in a peripheral blood mononuclear cell (PBMCs) infection model. To exclude strain-specific resistance, we tested the activity of Everolimus against Mtb strains of ancient and modern lineages. Furthermore, we investigated the Everolimus effect on ROS production and autophagy modulation during Mtb infection. Everolimus did not have a direct effect on mycobacteria viability and a negligible effect during Mtb infection in host cells, although it stimulated autophagy and ROS production. Despite being a biologically plausible HDT against TB, Everolimus does not exert a direct or indirect activity on Mtb. This case underlines the need for a careful approach to drug repurposing and implementation and the importance of pre-clinical experimental studies.

Disseminated tuberculosis in a lung transplant recipient presenting as tenosynovitis, subcutaneous nodules, and liver abscesses

Tuberculosis is of particular concern in lung transplant recipients. We present the case of a patient who received a double lung transplant from a deceased donor from Mexico and developed disseminated tuberculosis 60 days post-transplant manifested as tenosynovitis, liver abscesses, and subcutaneous nodules with no definitive lung allograft involvement. The recipient did not have evidence of tuberculosis on explanted lungs, had a negative interferon gamma release assay pre-transplant, and did not have risk factors for this infection. Mycobacterium tuberculosis should remain in the differential diagnosis of early post-transplant infections with atypical presentations, evidence of dissemination, or lack of improvement with appropriate antimicrobial coverage, even in the absence of typical lung findings.

Prevalence and Risk Factors of Active Tuberculosis in Patients with Rheumatic Diseases: A Multi-center, Cross-Sectional Study in China

Evidence of active tuberculosis (ATB) in patients with rheumatic diseases are research priorities but limited data from China have been reported. Research targeting patients not taking anti-TNF biologics are especially insufficient. We aimed to investigate the prevalence and risk factors of ATB in this at-risk population. We conducted a tertiary hospital-based, multi-center, cross-sectional study by using stratified multi-stage cluster sampling strategy to screen ATB in patients with rheumatic diseases. We estimated the prevalence of ATB in patients with rheumatic diseases and identified risk factors among those who were not taking anti-TNF biologic. A total of 13,550 patients with rheumatic diseases were enrolled, and the result showed the standardized prevalence of ATB according to the composition ratio of various types of rheumatic disease was 882/100000 (95% confidence interval (CI): 706-1057). Multivariable logistic regression analysis in patients not taking anti-TNF biologics showed that the independent risk factors of ATB were having systemic lupus erythematosus (SLE) (OR=2.722, 95% CI: 1.437-5.159, p=0.002), having Behcet's disease (BD) (OR= 5.261, 95% CI: 2.071-13.365, p<0.001), taking azathioprine(AZA) within the past two years (OR=2.095, 95% CI: 0.986-4.450, p=0.054), exposing to glucocorticoids ≥30mg/d for more than four weeks within the past two years (OR=2.031, 95% CI: 1.247-3.309, p=0.004) and having evidences of previous TB (OR= 6.185, 95% CI: 3.487-10.969, p<0.001). The prevalence of ATB was higher in patients with rheumatic diseases compared to the general population. Patients with SLE or BD, prolonged exposure to moderate to high dose of glucocorticoids and previous TB were independent risk factors for ATB.

Rapamycin modulates pulmonary pathology in a murine model of Mycobacterium tuberculosis infection

Tuberculosis (TB) treatment regimens are lengthy, causing non-adherence to treatment. Inadequate treatment can lead to relapse and the development of drug resistance TB. Furthermore, patients often exhibit residual lung damage even after cure, increasing the risk for relapse and development of other chronic respiratory illnesses. Host-directed therapeutics are emerging as an attractive means to augment the success of TB treatment. In this study, we used C3HeB/FeJ mice as an experimental model to investigate the potential role of rapamycin, a mammalian target of rapamycin inhibitor, as an adjunctive therapy candidate during the treatment of Mycobacterium tuberculosis infection with moxifloxacin. We report that administration of rapamycin with or without moxifloxacin reduced infection-induced lung inflammation, and the number and size of caseating necrotic granulomas. Results from this study strengthen the potential use of rapamycin and its analogs as adjunct TB therapy, and importantly underscore the utility of the C3HeB/FeJ mouse model as a preclinical tool for evaluating host-directed therapy candidates for the treatment of TB.

Summary: Rapamycin, an mTOR inhibitor, with or without moxifloxacin, reduces lung inflammation and the number and size of caseating necrotic granulomas in Mycobacterium tuberculosis-infected C3HeB/FeJ mice.

Incidence rate of active tuberculosis in solid organ transplant recipients: Data from a nationwide population cohort in a high-endemic country

BACKGROUND

The management of active tuberculosis (TB) in solid organ transplantation (SOT) recipients is challenging given the pharmacological interaction and the potential delays in diagnosis due to atypical presentation. The incidence rates (IRs) of post-SOT TB from the whole recipients' cohort in a high-endemic country have not been evaluated.

METHODS

We established a SOT cohort (n = 15 598) and confirmed cases of TB between 2011 and 2015 from the Korean National Health Insurance Database using ICD-10 codes. After excluding 1302 and 180 SOT-recipients due to age (<18 years) and presence of pre-SOT TB and/or treatment for latent TB during wash-out period between 2006 and cohort entry, we analyzed 14 116 SOT recipients and 70 580 individuals with no history of SOT matched by age and sex. The hazard ratios (HRs) of IRs were adjusted for age, sex, low-income status, diabetes mellitus, chronic co-morbidities, and anti-TNF-α therapy.

RESULTS

The IR of TB was significantly higher (adjusted HR [aHR]: 6.1, 95% confidence interval [CI]: 4.5-7.6) in SOT recipients (4.9/1000 person-years) than in non-SOT individuals (0.8/1000 person-years). Of the transplanted organs, the pancreas (pancreas alone and simultaneous pancreas-kidney) and lung had the highest IR (aHR: 16.3 [6.1-42.2] and 16.1 [5.9-43.8], respectively). The use of anti-thymocyte globulin and azathioprine was associated with a higher IR (aHR: 1.53 [1.01-2.43] and 3.92 [1.21-12.47], respectively), but basiliximab was associated with a lower IR (aHR: 0.67 [0.48-0.98]).

CONCLUSION

The IR of TB in SOT recipients, especially in the pancreas and lung, was significantly higher than that in the non-SOT population.

Mycobacteria: Selection of Transplant Candidates and Post-lung Transplant Outcomes

Mycobacterium is a large, clinically relevant bacterial genus made up of the agents of tuberculosis and leprosy and hundreds of species of saprophytic nontuberculous mycobacteria (NTM). Pathogenicity, clinical presentation, epidemiology, and antimicrobial susceptibilities are exceptionally diverse between species. Patients with end-stage lung disease and recipients of lung transplants are at a higher risk of developing NTM colonization and disease and of severe manifestations and outcomes of tuberculosis. Data from the past three decades have increased our knowledge of these infections in lung transplant recipients. Still, there are knowledge gaps to be addressed to further our understanding of risk factors and optimal treatments for mycobacterial infections in this population.

Tuberculosis in Biologic-naïve Patients With Rheumatoid Arthritis: Risk Factors and Tuberculosis Characteristics

OBJECTIVE

To investigate risk factors and characteristics of active tuberculosis (TB) in biologic-naïve patients with rheumatoid arthritis (RA).

METHODS

We conducted a population-based case-control study using the Swedish Rheumatology Quality Register, the National Patient Register, and the Tuberculosis Register to identify RA patients with active TB and matched RA controls without TB between 2001-2014. Clinical data were obtained from medical records. TB risk was estimated as adjusted OR (aOR) with 95% CI using univariate and multivariable logistic regression analyses.

RESULTS

After validation of diagnoses, the study included 31 RA patients with TB and 122 matched RA controls. All except 3 cases had reactivation of latent TB. Pulmonary TB was most prevalent (84%). Ever use of methotrexate was not associated with increased TB risk (aOR 0.8, 95% CI 0.3-2.0), whereas ever treatment with leflunomide (aOR 6.0, 95% CI 1.5-24.7), azathioprine (aOR 3.8, 95% CI 1.1-13.8), and prednisolone (PSL; aOR 2.4, 95% CI 1.0-6.0) was. There were no significant differences between maximum dose of PSL, treatment duration with PSL before TB, or cumulative dose of PSL the year before TB diagnosis between cases and controls. Obstructive pulmonary disease was associated with an increased TB risk (aOR 3.9, 95% CI 1.5-10.7).

CONCLUSION

Several RA-associated factors may contribute to increased TB risk in biologic-naïve patients with RA, making the risk of TB activation difficult to predict in the individual patient. To further decrease TB in patients with RA, the results suggest that screening for latent TB should also be considered in biologic-naïve patients.

Active tuberculosis in inflammatory bowel disease patients under treatment from an endemic area in Latin America

BACKGROUND

There has been an increase in cases of inflammatory bowel disease (IBD) in recent years. There is also greater access and availability of immunosuppressive and biological agents, which increase the risk of opportunistic infection despite improving the quality of life and promoting mucosal healing. Tuberculosis (TB) remains a public health problem, and it has a high incidence in several countries. Therefore, knowledge of the risk of developing TB in patients with IBD is important.

AIM

To evaluate the risk of active TB in patients with IBD under treatment from an endemic area in Latin America.

METHODS

A standard questionnaire included demographic variables, clinical aspects of IBD disease, history of active TB during treatment, active TB characteristics and evolution, initial screening and results and time from the start of anti-tumor necrosis factor alpha (TNFα) to TB development.

RESULTS

Azathioprine, anti-TNFα and the combination of these two drugs were associated with a higher risk of active TB incidence. The TNFα blockers increased the relative risk of developing active TB compared to other treatments. All four multivariable models showed that the use of TNFα blockers alone or in combination with azathioprine was an important risk factor for the incidence of active TB. After adjustment for sex, age, type of IBD and latent TB, anti-TNFα with azathioprine increased the relative risk to 17.8 times more than conventional treatment. Late TB, which was diagnosed 3 mo after the start of anti-TNFα, was the most frequent.

CONCLUSION

Treatment with anti-TNFα increased the risk of active TB in IBD patients from an endemic area in Latin America. This risk was increased when anti-TNFα was combined with azathioprine. The time from the beginning of the treatment to the active TB diagnosis suggests a new TB infection.

Empiric vs screening-based use of isoniazid for tuberculosis prophylaxis: Safety and effectiveness in lung transplant recipients in Saudi Arabia

Background

Tuberculosis (TB) is a major complication following transplantation. The likelihood of TB may be increased in transplant patients living in TB‐endemic areas such as Saudi Arabia. In areas where TB is less common, guidelines recommend isoniazid (INH) for TB prophylaxis depending on patient and donor screening results. However, in TB‐endemic regions, studies have supported its use in all transplant patients regardless of TB screening results. This study aimed to compare the safety and effectiveness of administering INH prophylaxis therapy based on the TB screening results of lung transplant (LT) recipients.

Methods

We conducted a single‐center retrospective cohort study on LT recipients. The outcomes were compared between patients who were administered screening‐based prophylaxis (SBP) with INH based on their tuberculin skin tests (TSTs) or QuantiFERON results and those who were administered empirical prophylaxis (EP) with INH regardless of TB screening results. The primary endpoint was the incidence of TB infection, and the secondary endpoints were INH‐induced hepatotoxicity and INH resistance.

Results

A total of 50 patients received SBP and 30 received EP. TB incidences were 8% and 0%, respectively (P = .0487). One of these patients had INH resistance, and one patient experienced INH‐induced hepatotoxicity (P = .1591); both were in the SBP group.

Conclusion

The low rates of TB infection, INH‐induced hepatotoxicity, and INH resistance in the EP group suggest that INH prophylaxis appears to prevent TB and can be safely used in all LT recipients. However, prospective studies using large sample sizes are required to confirm these findings.

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.

Trends in diagnostic methods and treatment of latent tuberculosis infection in a tertiary care center from 2000 to 2017

Screening for latent tuberculosis infection (LTBI) is indicated before immunosuppressive therapies but is complicated by lack of a gold standard and limited by, e.g., immunosuppression. This study aimed to investigate a series of patients diagnosed with LTBI during screening before immunosuppressive therapy, describing how the use of diagnostic tests and treatment evolved over time. This retrospective cohort study included all individuals diagnosed with LTBI during screening before intended immunosuppressive therapy in a tertiary care hospital between January 2000 and December 2017. Evidence for LTBI, including history, tuberculin skin test (TST), QuantiFERON (QFT) result and suggestive lesions on chest radiography (CXR), and CT scan if available, was analyzed. The study included 295 individuals with LTBI, with median follow-up of 3.8 years (IQR 1.7–7.4 years). During screening, TST, QFT, and CXR were positive in 80.8%, 53.4%, and 22.7%, respectively. Chest CT revealed lesions associated with past tuberculosis infection in around 70%, significantly more frequent than CXR. In patients diagnosed with LTBI, we observed that the use of TST declined over time whereas the use of QFT increased, and that isoniazid was replaced with rifampicin as preferential treatment. Preventive treatment was started in 82.3%, of whom 88.6% completed treatment. During follow-up, no individuals developed active tuberculosis. The diagnosis of LTBI was based on history, TST, QFT, and/or CXR in nearly every possible combination, but mostly on TST and QFT. The most striking trends were the decreased use of TST, increased use of QFT, and the replacement of isoniazid with rifampicin for treatment.

Prevention Strategies to Minimize the Infection Risk Associated with Biologic and Targeted Immunomodulators

The introduction of biologic and targeted immunomodulators is a significant breakthrough in the therapeutic area of various fields of medicine. The occurrence of serious infections, a complication of secondary immunosuppression associated with these agents, leads to increased morbidity and mortality. Implementing preventive strategies could minimize infection-related complications and improve therapeutic outcomes. The purpose of this review is to focus on current evident approaches regarding screening, monitoring, preventing (immunization and chemoprophylaxis), and management of infections in patients who are candidates for about 70 biologic and targeted immunomodulators. Recommendations are based on relevant guidelines, especially the ESCMID Study Group for Infections in Compromised Hosts (ESGICH) Consensus Document series published in 2018.

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.

Mycobacterium tuberculosis infections in solid organ transplantation: Guidelines from the infectious diseases community of practice of the American Society of Transplantation

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of tuberculosis in the pre- and post-transplant period. The challenges of screening for both latent and active TB in the setting of transplantation are reviewed. The use of interferon gamma release assays for detection of latent tuberculosis is discussed and compared to tuberculin skin testing. Given the limitations of both testing modality, it is important to consider exposure history and chest imaging. The clinical manifestations of active tuberculosis in transplantation are covered. New recommendations for treatment of latent tuberculosis and active tuberculosis are included.

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.

Trends of Medication Usage and Associated Outcomes for Taiwanese Patients with Inflammatory Bowel Disease from 2001 to 2015

BACKGROUND

No nationwide, long-term follow-up study has assessed medication-associated outcomes for Asian patients with inflammatory bowel disease (IBD). This study examined medication-associated outcomes for Taiwanese patients with IBD.

METHODS

In this nationwide cohort study, 3806 patients who had received catastrophic illness registration for IBD from 2001 to 2015 were enrolled.

RESULTS

A higher accumulated dosage of 5-aminosalicylic acid (5-ASA) was associated with decreased risks of hospitalization (hazard ratio (HR) = 0.6) and operation (HR = 0.5). Thiopurine was associated with increased risks of hospitalization (HR = 2.1 in the high-dosage group) and tuberculosis (TB; HR = 3.6) reactivation but not with operation risk. A higher accumulated dosage of anti-TNF-α agents was associated with increased risks of hospitalization (HR = 3.3), operation (HR = 2.9), hepatitis B (HR = 4.3), and TB (HR = 5.1) reactivation. Corticosteroids were associated with increased risks of hospitalization (HR = 3.5 in the high-dosage group), risk of operation, hepatitis B (HR = 2.8) and TB (HR = 2.8) reactivation.

CONCLUSIONS

5-ASA usage is associated with decreased risks of hospitalization and operation for patients with IBD, whereas thiopurine, corticosteroids, and anti-TNF-α agents are associated with increased risks of hospitalization and hepatitis B and TB reactivation.

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.

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.