Molecular Epidemiology of Rifampicin-Resistant Mycobacterium tuberculosis by GeneXpert MTB/RIF Assay in Renal Transplant Recipients: A Single-Center Experience

Objectives: There are scarce data on the incidence and resistance pattern of rifampicin-resistant Mycobacterium tuberculosis among kidney transplant recipients. Materials and Methods: This is a retrospective, single-center study of kidney transplant recipients suspected of M. tuberculosis infection. The GeneXpert assay we used detected mutations in the rpoB gene that confer rifampicin resistance using 5 overlapping probes (A, B, C, D, and E). The probes can detect mutations in the codons 507 to 511 (probe A), 511 to 518 (probe B), 518 to 523 (probe C), 523 to 529 (probe D), and 529 to 533 (probe E). We also detailed the treatment protocol and outcomes of kidney transplant recipients infected with rifampicin-resistant M. tuberculosis. Results: In total, 2700 samples were processed during the period from October 2018 to February 2022 with successful results in 2640 samples (97.04%). One hundred and ninety (7.19%) samples were positive for M. tuberculosis, and rifampicin resistance was detected in 12 (0.45%) cases (11 pulmonary, 1 genitourinary). The most common rpoB mutation was located in the region of probe E (75.0%), followed by probe A (16.6%) and in 1 combination probe DE (8.33%). The rpoB mutations were not observed in probe B and probe C. Six patients received bedaquiline-based treatment for a short course of 11 months, whereas the other 6 patients required a long course of 18 to 20 months. Three patients died, 2 were lost to follow-up, and 7 were cured. During treatment, 4 patients experienced acute rejection, and 1 graft loss was reported. Conclusions: We report for the first time the incidence and pattern of rifampicin resistance among kidney transplant recipients with tuberculosis infection. Further investigations are required for exploring the molecular and clinical phenotypes.