Assessments of Different Methods for Testing Heteroresistance to Rifampicin in Tubercle Bacillus

This study was undertaken to compare the ability of four clinically used methods to detect the heteroresistance of the tubercle bacillus to Rifampicin (Rif). A total of 94 sputum smear-positive samples of re-treated tuberculosis (TB) patients were employed. Rif-resistant tubercle bacillus tests were carried out by four methods: Lowenstein-Jensen cultures (L-J), reverse transcription-polymerase chain reaction (RT-PCR), microscopic observation drug susceptibility (MODS), and high-resolution melting (HRM). The rates of detection of Rif-resistant bacteria by of L-J, RT-PCR, MODS, and HRM were 35.1% (33), 36.4% (35), 36.2% (34), and 16.0% (15), respectively. The rate of detection by RT-PCR was slightly higher than that of L-J and MODS (P > 0.05) and significantly higher than that of HRM (P < 0.01). The median detection time of L-J, RT-PCR, MODS, and HRM was 60 d, 1 d, 9 d, and 1 d, respectively. Smear-positive TB can be directly and rapidly detected using RT-PCR and MODS technologies. The positive rates of RT-PCR and MODS were not only highly consistent with that of L-J and remarkably higher than that of HRM, but also were obtained in a markedly shortened time. The combination of MODS and RT-PCR has a synergistic effect on the speed of detection of heteroresistance, which is of great value for the timely and accurate diagnosis, guiding the clinicians in formulating the optimal treatment of smear-positive pulmonary tuberculosis.