Case Report of False Rifampin Resistance with Xpert® MTB/RIF from an HIV Infected Patient

Background Tuberculosis is one of the main infectious diseases threatening human health, especially in HIV co-infected patients. Xpert® MTB/RIF assay amplifies the rpoB gene of MTB was recommended by the World Health Organization as the initial diagnostic test in cases of suspected infections with Mycobacterium tuberculosis (MTB) or HIV-coinfected TB. Methods A 44-year-old male HIV-positive patient co-infected with MTB presented with low-grade fever for 3 months. Rifampicin (RIF) resistance was detected in the celiac pus but not in the pleural effusion using Xpert® MTB/RIF assay. The same samples were then sequenced by next-generation sequencing (NGS) and in-house PCR for rpoB gene. Results The results of NGS and in-house PCR, however, were paradoxical in the same samples with low or no mutation sequences of RIF resistance. The patient's tuberculosis (TB) therapy was optimized based on first-line anti-TB drugs and antiretroviral treatment. The patient improved with this therapy. Conclusions Even with high specificity, false positive results remain possible and RIF resistance detection by Xpert must be considered for clinical interpretation.