Use of Filtration and Cost-Effective Molecular Laboratory Detection of the Mycobacteria tuberculosis Complex

• Main Authors: Hui-Zin Tu, 竇慧琴
• Other Authors: Yusen Eason Lin
• Format: Others
• Language: en_US
• Online Access: http://ndltd.ncl.edu.tw/handle/13541277374782866799

碩士 === 國立高雄師範大學 === 環境教育研究所 === 96 === Pseudo-outbreaks of tuberculosis (TB) occurred in Taiwan caused management problems because many patients may undergo preliminary anti-tuberculosis therapy and isolation. Thus, it is important to develop accurate and rapid procedures to detect TB. The false positive results may be due to acid-fast stain of non-tuberculosis mycobacterium (NTM) with the laboratory tap water that is used to process the specimens. NTM is often found in tap water and can be lead to a false positive acid-fast stain result. Thus, the effectiveness of point-of-use 0.2 μm water filter to reduce false positive acid-fast stain was evaluated. Detection of deoxyribonucleic acid (DNA) in 361 acid-fast positive respiratory specimens for M. tuberculosis complex was also evaluated with the homogenous strand displacement amplification (SDA) technology and fluorescent energy (ET). Using mycobacteria cultures as gold standard, the false positive rate of samples treated by filtered water (1.2%, 7/562) is significant lower than samples treated by tap water (10.7%, 60/562) and deionized water (8.7%, 49/562). The specificity and positive predictive value for samples treated with filtered water (98.6% and 88.3%, respectively) is significantly higher than that for samples with tap water (87.6% and 40.6%, respectively) and deionized water (89.9% and 46.2%, respectively). When the PCR assay was used in smear positive specimens, the overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) was 87.2%, 97.6%, 97.7% and 86.6%, respectively. The sensitivity and negative predictive value (NPV) could increase to 91.8% and 91.0% if clinical manifestation was included. We demonstrated that use of point-of-use filter removed NTM from water and led to significantly lower false positive results in acid-fast stain for TB in laboratory with high probability of NTM contamination in its tap water. SDA assay for detection of M. tuberculosis complex was accurate and rapid.