National Center for Tuberculosis and Lung Diseases, Tbilisi, Georgia, USA.
PLoS One. 2012;7(2):e31563. doi: 10.1371/journal.pone.0031563. Epub 2012 Feb 9.
The WHO has recommended the implementation of rapid diagnostic tests to detect and help combat M/XDR tuberculosis (TB). There are limited data on the performance and impact of these tests in field settings.
The performance of the commercially available Genotype MTBDRplus molecular assay was compared to conventional methods including AFB smear, culture and drug susceptibility testing (DST) using both an absolute concentration method on Löwenstein-Jensen media and broth-based method using the MGIT 960 system. Sputum specimens were obtained from TB suspects in the country of Georgia who received care through the National TB Program.
Among 500 AFB smear-positive sputum specimens, 458 (91.6%) had both a positive sputum culture for Mycobacterium tuberculosis and a valid MTBDRplus assay result. The MTBDRplus assay detected isoniazid (INH) resistance directly from the sputum specimen in 159 (89.8%) of 177 specimens and MDR-TB in 109 (95.6%) of 114 specimens compared to conventional methods. There was high agreement between the MTBDRplus assay and conventional DST results in detecting MDR-TB (kappa = 0.95, p<0.01). The most prevalent INH resistance mutation was S315T (78%) in the katG codon and the most common rifampicin resistance mutation was S531L (68%) in the rpoB codon. Among 13 specimens from TB suspects with negative sputum cultures, 7 had a positive MTBDRplus assay (3 with MDR-TB). The time to detection of MDR-TB was significantly less using the MTBDRplus assay (4.2 days) compared to the use of standard phenotypic tests (67.3 days with solid media and 21.6 days with broth-based media).
Compared to conventional methods, the MTBDRplus assay had high accuracy and significantly reduced time to detection of MDR-TB in an area with high MDR-TB prevalence. The use of rapid molecular diagnostic tests for TB and drug resistance should increase the proportion of patients promptly placed on appropriate therapy.
世界卫生组织（WHO）建议实施快速诊断检测，以发现并帮助治疗广泛耐药和耐多药结核病（TB）。然而，在现场环境中，这些检测的性能和影响的数据有限。
本研究比较了市售的 Genotype MTBDRplus 分子检测与常规方法，包括在 Löwenstein-Jensen 培养基上使用绝对浓度法和在 MGIT 960 系统中使用基于肉汤的方法对 AFB 涂片、培养和药敏试验（DST）的检测性能。痰标本取自格鲁吉亚国家结核病规划下接受治疗的结核病疑似患者。
在 500 份 AFB 涂片阳性的痰标本中，458 份（91.6%）痰培养阳性的结核分枝杆菌标本和有效的 MTBDRplus 检测结果均为阳性。MTBDRplus 检测直接从 177 份标本中的 159 份（89.8%）和 114 份标本中的 109 份（95.6%）中检测到异烟肼（INH）耐药和耐多药，与传统方法相比。MTBDRplus 检测与常规 DST 结果在检测耐多药结核病（MDR-TB）方面具有高度一致性（kappa=0.95，p<0.01）。katG 密码子中最常见的 INH 耐药突变是 S315T（78%），rpoB 密码子中最常见的利福平耐药突变是 S531L（68%）。在 13 份来自痰培养阴性的结核病疑似患者的标本中，有 7 份 MTBDRplus 检测结果阳性（3 份为耐多药）。与使用标准表型检测相比（固体培养基 67.3 天，基于肉汤的培养基 21.6 天），MTBDRplus 检测显著缩短了耐多药结核病的检测时间（4.2 天）。
与传统方法相比，MTBDRplus 检测在耐多药结核病高发地区具有较高的准确性，并显著缩短了耐多药结核病的检测时间。快速分子诊断检测在结核病和耐药性方面的应用应增加及时进行适当治疗的患者比例。
