Risk of active tuberculosis infection in kidney transplantation recipients: A matched comparative nationwide cohort study

Diagnosis of Latent Tuberculosis Infection in Hemodialysis Patients: TST versus T-SPOT.TB

Hemodialysis (HD) patients should be screened for latent tuberculosis (TB) infection. We aimed to determine the frequency of latent TB infection in HD patients and to compare the effectiveness of the tests used. The files of 56 HD patients followed between 1 January 2021 and 1 October 2022 were retrospectively analyzed. Demographic data, the presence of the Bacillus Calmette-Guerin (BCG) vaccine, whether or not the patients had previously received treatment for TB before, the status of encountering a patient with active TB of patients over 18 years of age, without active tuberculosis and who had a T-SPOT.TB test or a Tuberculin Skin Test (TST) were obtained from the patient files. The presence of previous TB in a posterior-anterior (PA) chest X-ray was obtained by evaluating PA chest X-rays taken routinely. Of the patients, 60.7% (n = 34) were male and their mean age was 60.18 ± 14.85 years. The mean duration of dialysis was 6.43 ± 6.03 years, and 76.8% (n = 43) had 2 BCG scars. The T-SPOT.TB test was positive in 32.1% (n = 18). Only 20 patients (35.7%) had a TST and all had negative results. While the mean age of those with positive T-SPOT.TB results was higher (p = 0.003), the time taken to enter HD was shorter (p = 0.029). T-SPOT.TB test positivity was higher in the group that had encountered active TB patients (p = 0.033). However, no significant difference was found between T-SPOT.TB results according to BCG vaccine, albumin, urea and lymphocyte levels. Although T-SPOT.TB test positivity was higher in patients with a previous TB finding in a PA chest X-ray, there was no statistically significant difference (p = 0.093). The applicability of the TST in the diagnosis of latent TB infection in HD patients is difficult and it is likely to give false-negative results. The T-SPOT.TB test is not affected by the BCG vaccine and immunosuppression. Therefore, using the T-SPOT.TB test would be a more appropriate and practical approach in the diagnosis of latent TB in HD patients.

Mycobacterium Tuberculosis Infection after Kidney Transplantation: A Comprehensive Review

Tuberculosis (TB) in kidney transplant (KT) recipients is an important opportunistic infection with higher incidence and prevalence than in the general population and is associated with important morbidity and mortality. We performed an extensive literature review of articles published between 1 January 2000 and 15 June 2022 to provide an evidence-based review of epidemiology, pathogenesis, diagnosis, treatment and outcomes of TB in KT recipients. We included all studies which reported epidemiological and/or outcome data regarding active TB in KT, and we approached the diagnostic and treatment challenges according to the current guidelines. Prevalence of active TB in KT recipients ranges between 0.3–15.2%. KT recipients with active TB could have a rejection rate up to 55.6%, a rate of graft loss that varies from 2.2% to 66.6% and a mortality rate up to 60%. Understanding the epidemiological risk, risk factors, transmission modalities, diagnosis and treatment challenges is critical for clinicians in providing an appropriate management for KT with TB. Among diagnostic challenges, which are at the same time associated with delay in management, the following should be considered: atypical clinical presentation, association with co-infections, decreased predictive values of screening tests, diverse radiological aspects and particular diagnostic methods. Regarding treatment challenges in KT recipients with TB, drug interactions, drug toxicities and therapeutical adherence must be considered.

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.