Pang Yu, Su Biyi, Zheng Huiwen, Zhang Zhiguo, Ma Aijing, Wang Yufeng, Zhao Yanlin
National Center for Tuberculosis Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
State Key Laboratory of Respiratory Diseases, Department of Clinical Laboratory, Guangzhou Chest Hospital, Guangzhou, China.
Biomed Res Int. 2016;2016:5972021. doi: 10.1155/2016/5972021. Epub 2016 Dec 19.
Despite the demonstration of excellent performance, mycobacterial growth in BACTEC MGIT 960 can go undetected. The aim of this study was to investigate the prevalence of "false-negative" culture sample in Beijing and the potential factors associated with the detection failures by MGIT 960. Of the 577 sputum samples tested, 141 (24.4%) were culture-positive for mycobacteria, of which 133 (94.3%) were automatically determined by MGIT 960 system and 8 (5.7%) were positive for visual growth (false negative by MGIT). Statistical analysis showed that positive grade of specimen had no influence on the false-negative rate by MGIT 960 system ( = 2.207, = 0.820). In addition, the mean time to detection (TTD) was 241.4 (range: 224-261) hours for false-negative group and 186.8 (range: 173-199) hours for positive group. The difference in TTD between false-negative and positive groups was statistically significant ( < 0.01). In conclusion, our data demonstrate that the automatic MGIT missed a small portion of bacteriological mycobacterial patients. In addition, the poor growth rate rather than the low grade of AFB smear is associated with the detection failure by MGIT. Our findings highlight the notion that manual inspection for all instrument-negative MGIT tubes will bring about considerable benefit to patients and clinicians.
尽管已证明BACTEC MGIT 960性能出色，但分枝杆菌在其中的生长仍可能未被检测到。本研究的目的是调查北京地区“假阴性”培养样本的患病率以及与MGIT 960检测失败相关的潜在因素。在检测的577份痰标本中，141份（24.4%）分枝杆菌培养呈阳性，其中133份（94.3%）由MGIT 960系统自动判定，8份（5.7%）为肉眼可见生长阳性（MGIT假阴性）。统计分析表明，标本的阳性等级对MGIT 960系统的假阴性率没有影响（χ² = 2.207，P = 0.820）。此外，假阴性组的平均检测时间（TTD）为241.4（范围：224 - 261）小时，阳性组为186.8（范围：173 - 199）小时。假阴性组和阳性组的TTD差异具有统计学意义（P < 0.01）。总之，我们的数据表明，MGIT自动检测遗漏了一小部分细菌学确诊的分枝杆菌患者。此外，生长速度慢而非抗酸杆菌涂片等级低与MGIT检测失败有关。我们的研究结果凸显了对所有仪器判定为阴性的MGIT培养管进行人工检查将给患者和临床医生带来显著益处的观点。
