Objective  To evaluate the diagnostic efficacy of different pathogen detection methods in active tuberculosis (ATB) of kidney transplant recipients (KTRs) and analyze their diagnostic value in different types of clinical specimens.

Methods  A retrospective observational study was conducted, including adult KTRs with suspected ATB from the Eighth Medical Center of Chinese People's Liberation Army General Hospital from January 2020 to January 2025. Baseline data of the recipients were collected and analyzed, and the diagnostic criteria were based on a composite reference standard (including clinical diagnosis and bacteriological confirmation). The single-detection efficacy of acid-fast staining smear, mycobacterium tuberculosis culture, Xpert test for the detection of mycobacterium tuberculosis nucleic acid and resistance to rifampicin (Xpert MTB/RIF), as well as tuberculosis or non-tuberculosis mycobacterial DNA detection was compared. The differences in sensitivity among different methods were analyzed.

Results  A total of 95 KTRs with suspected ATB and 136 specimens were included. And 52 cases were diagnosed as ATB, among which 48 cases were confirmed by bacteriological means (92%). The sensitivity of Xpert MTB/RIF and DNA detection (0.55 and 0.52, respectively) was significantly higher than that of acid-fast staining smear (0.30) and mycobacterium tuberculosis culture (0.35) (P < 0.01). There was a statistically significant difference in the bacteriological diagnosis rate among different specimen types (P = 0.035). The detection sensitivity of each method was the highest in pus, puncture tissue and bronchoalveolar lavage fluid, followed by sputum and pleural and abdominal effusions, and the lowest in cerebrospinal fluid.

Conclusions  The sensitivity of nucleic acid amplification technology for immunosuppressed KTRs is slightly reduced, but it should still be recommended as the preferred initial screening tool. The comprehensive strategy of "multi-site sampling (prior to obtaining high bacterial load specimens) combined with multiple method detection" may improve the diagnostic efficacy.