The value of Xpert MTB/RIF assay of urine samples in the early diagnosis of smear-negative urinary tuberculosis

Abstract

Background According to reports, between 30 and 40 percent of extrapulmonary tuberculosis (EPTB) cases are caused by urinary tract tuberculosis (UTB). It is critical to identify UTB quickly since it frequently precedes delayed medical attention, which can have detrimental effects. This study examined the use of Xpert MTB/RIF, a PCR test that can detect MTB as well as resistance to an important drug, rifampicin (RIF), in UTB particularly, for the early identification of UTB. Methods 180 participants with clinically presumptive UTB whose urine samples were chosen for urine sediment smear, culture, Xpert MTB/RIF, and TB-DNA testing at Henan Chest Hospital between January 2019 and July 2022. Evaluation of test performance using Composite Reference Standards (CRSs). We studied and compared the positivity rate for various tests using the t-test. The effectiveness of smear, culture, Xpert MTB/RIF, and TB-DNA was assessed using McNemar test. Results In this subject, a total of 108 participants were diagnosed with UTB, and the positivity rate was 67.1%. Compared with CRS, the positivity rate of Xpert MTB/RIF, smear, culture, and TB-DNA was 29.69% (19/64, P < 0.001), 7.56% (9/119, P < 0.1), 12.12% (4/33, P > 0.05), and 18.75% (6/32, P < 0.1), respectively. The sensitivity of Xpert MTB/RIF assay was significantly better than that of smear and culture tests (78.9% vs. 77.8%, P < 0.05; 78.9% vs. 75%, P < 0.05). Under CRS, the positivity rate for Xpert, culture, and TB-DNA was 31.6% (6/19, P < 0.1), 6.2% (1/16, P > 0.05), and 26.7% (4/15, P > 0.05) for TB-DNA, respectively, compared to smear negative. Xpert MTB/RIF assay specificity was significant for culture and TB-DNA (53.6% vs. 25%, P < 0.01; 53.6% vs. 38.9%, P < 0.05), and Xpert MTB/RIF assay FPV was significant for culture and TB-DNA (53.6% vs. 0%, P < 0.001; 53.6% vs. 0%, P < 0.001). Conclusion Xpert MTB/RIF outperforms smear, cultures, and TB-DNA in detecting UTB, plus Xpert MTB/RIF is better suited for early diagnosis in smear-negative UTB.

Evaluasi sensitivitas dan spesifisitas Xpert MTB RIF dan Xpert MTB RIF Ultra pada berbagai spesimen untuk mendiagnosis tuberkulosis ekstra paru: Sebuah telaah literatur sistematis

“…Hasil penelusuran literatur pemeriksaan Xpert MTB RIF terhadap cairan urin didapatkan 5 studi yang melibatkan 103 subjek penelitian dengan nilai rerata sensitivitas mencapai 65.20% (33.3-100%) dan spesifisitas mencapai 95.06% (77-100%). Hasil studi pada penelitian ini terhadap hasil pemeriksaan Xpert MTB RIF pada spesimen urin mendapatkan hasil yang membandingkan pemeriksaan Xpert MTB RIF dengan Acid-fast Bacilli (AFB), kultur dan pemeriksaan MTB deoxyribonucleic acid (TB DNA) PCR, sensitivitas pemeriksaan Xpert MTB RIF adalah 78.9% dengan spesifisitas 68.6%, nilai ini lebih baik dari pemeriksaan AFB (77.8/33.6%) dan berada di bawah pemeriksaan TB-DNA (83.3/38.5%) (Wang, Tan, Lei, Yuan, Li, Zhao, & Wang, 2022).…”