Tuberculosis in solid organ transplant patients

Clinical characteristics of tuberculous infection following renal transplantation

OBJECTIVE

This study investigated the clinical characteristics of patients with tuberculosis (TB) following renal transplantation (RT) in order to identify markers or signs that can facilitate early diagnosis.

METHODS

A retrospective analysis was performed on 12 cases of Mycobacterium tuberculosis infection treated at our hospital between 2005 and 2020.

RESULTS

The incidence of TB after RT at our hospital was 0.9%, and the median postoperative onset time was 22 months. The average age of patients included in our analysis was 44.2 ± 9.4 years; 11 of the 12 patients were male, and most patients had (low) fever as the first or only manifestation. Five patients had respiratory symptoms; 5 had typical computed tomography (CT) presentation; and 2 had a confirmed history of TB. Two sputum smears from 12 patients were positive by acid fast staining, and M. tuberculosis was detected in peripheral blood samples by metagenomic next-generation sequencing (NGS). One patient had a positive result in the purified protein derivative (PPD) test, 7 were positive with the interferon gamma release assay (IGRA), 8/12 patients were confirmed to have TB infection by NGS and 1 was confirmed positive by lung biopsy.

CONCLUSION

Because of the use of immunosuppressive agents, most patients with TB following RT have atypical clinical symptoms and CT findings, and may have a high probability of a false negative result with the traditional PPD test and a low probability of M. tuberculosis detection, making early diagnosis difficult. Therefore, in RT recipients with prolonged fever of unknown origin and unusual clinical manifestations, especially those who are unresponsive to antibiotic treatment, a diagnosis of TB should be considered. The interferon gamma release assay and NGS are relatively new detection methods with high sensitivity and specificity; these along with regular, repeated testing by various approaches can aid the early diagnosis of TB.

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.

Treatment of tuberculosis infection complicated with liver transplant

Liver transplant is considered the best choice for treating various end-stage liver diseases either at home or abroad. Among patients of liver transplant complicated with tuberculosis (TB), the incidence and mortality of postoperative active TB are bound to increase remarkably. Diagnosing and treating TB in patients with end-stage liver diseases who received immunosuppressants after liver transplant are difficult because of the absence of specific clinical manifestations while being complicated with TB, reduced sensitivity to cellular immunoassay, and interaction between anti-TB drugs and immunosuppressants. Therefore, the screening of high-risk groups, improvement in diagnostic accuracy, preoperative treatment, and reduced interaction between anti-TB drugs and immunosuppressants can help optimize diagnosis and treatment regimes and thus further improve the prognosis of patients.

Novel benzimidazole–oxadiazole hybrid molecules as promising antimicrobial agents

In the present study, we describe the design and expeditious synthesis of novel 2-aryl-5-(3-aryl-[1,2,4]-oxadiazol-5-yl)-1-methyl-1H-benzo[d]imidazole hybrid molecules as promising antimicrobial agents.

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.

Risk factors for hepatotoxicity in solid organ transplants recipients being treated for tuberculosis

BACKGROUND

Tuberculosis (TB) is associated with high morbidity and mortality in solid organ transplant (SOT) recipients. Also, SOT patients have a 20- to 74-fold increase in the chance of developing TB compared to the general population. Here we evaluated the incidence of hepatotoxicity in SOT recipients on treatment for TB and determined risk factors for liver toxicity in these patients.

PATIENTS AND METHODS

Retrospective cohort conducted in a reference hospital for SOT in Southern Brazil. All SOT recipients who underwent TB treatment during the years 2000-2012 were considered for the study.

RESULTS

A total of 69 patients were included in the study and 23 had liver toxicity (incidence 33.3%). Independent risk factors for hepatotoxicity were rifampin use at doses of ≥600 mg daily (P = .016; OR 2.47; 95% CI, 1.18-5.15) and lung transplantation (P = .017; OR 2.05; 95% CI, 1.14-3.70). Kidney transplantation appeared as a protective factor (P = .036; OR 0.50; 95% CI, 0.26-0.96). Mortality was higher in the patients who had hepatotoxicity (43.5%), compared with those who did not (19.6%).

CONCLUSION

In this study, the use of rifampin at doses of 600 mg daily or higher was found to be an independent risk factor for liver toxicity in SOT recipients. The importance of additional risk factors for hepatotoxicity, such as lung transplantation as well as the protective role of kidney transplantation, should be better investigated in SOT recipients being treated for TB.

Clinical features and outcomes of tuberculosis in transplant recipients as compared with the general population: a retrospective matched cohort study

There are no previous studies comparing tuberculosis in transplant recipients (TRs) with other hosts. We compared the characteristics and outcomes of tuberculosis in TRs and patients from the general population. Twenty-two TRs who developed tuberculosis from 1996 through 2010 at a tertiary hospital were included. Each TR was matched by age, gender and year of diagnosis with four controls selected from among non-TR non-human immunodeficiency virus patients with tuberculosis. TRs (21 patients, 96%) had more factors predisposing to tuberculosis than non-TRs (33, 38%) (p <0.001). Pulmonary tuberculosis was more common in non-TRs (77 (88%) vs. 12 TRs (55%); p 0.001); disseminated tuberculosis was more frequent in TRs (five (23%) vs. four non-TRs (5%); p 0.005). Time from clinical suspicion of tuberculosis to definitive diagnosis was longer in TRs (median of 14 days) than in non-TRs (median of 0 days) (p <0.001), and invasive procedures were more often required (12 (55%) TRs and 15 (17%) non-TRs, respectively; p 0.001). Tuberculosis was diagnosed post-mortem in three TRs (14%) and in no non-TRs (p <0.001). Rates of toxicity associated with antituberculous therapy were 38% in TRs (six patients) and 10% (seven patients) in non-TRs (p 0.014). Tuberculosis-related mortality rates in TRs and non-TRs were 18% and 6%, respectively (p 0.057). The adjusted Cox regression analysis showed that the only predictor of tuberculosis-related mortality was a higher number of organs with tuberculosis involvement (adjusted hazard ratio 8.6; 95% CI 1.2-63). In conclusion, manifestations of tuberculosis in TRs differ from those in normal hosts. Post-transplant tuberculosis resists timely diagnosis, and is associated with a higher risk of death before a diagnosis can be made.

Genetic variants of innate immune receptors and infections after liver transplantation

Infection is the leading cause of complication after liver transplantation, causing morbidity and mortality in the first months after surgery. Allograft rejection is mediated through adaptive immunological responses, and thus immunosuppressive therapy is necessary after transplantation. In this setting, the presence of genetic variants of innate immunity receptors may increase the risk of post-transplant infection, in comparison with patients carrying wild-type alleles. Numerous studies have investigated the role of genetic variants of innate immune receptors and the risk of complication after liver transplantation, but their results are discordant. Toll-like receptors and mannose-binding lectin are arguably the most important studied molecules; however, many other receptors could increase the risk of infection after transplantation. In this article, we review the published studies analyzing the impact of genetic variants in the innate immune system on the development of infectious complications after liver transplantation.