Department of Microbiology, Seth G.S. Medical College and KEM Hospital, Mumbai, Maharashtra, India.
Department of Microbiology, Seth G.S. Medical College and KEM Hospital, Mumbai, Maharashtra; Telangana Diagnostics Central Laboratory, Hyderabad, Telangana, India.
Int J Mycobacteriol. 2023 Apr-Jun;12(2):151-156. doi: 10.4103/ijmy.ijmy_86_23.
In patients unable to expectorate good quality sputum or with minimal to none sputum production, bronchoscopic specimens may be collected. The objective of the study is to determine the use of Xpert MTB/RIF assay and line probe assay (LPA) in the diagnosis of pulmonary TB (PTB) using specimens collected by bronchoscopy in a tertiary care center.
Bronchoscopy specimens received in the TB laboratory were processed by microscopy, Xpert MTB/RIF assay, LPA, and mycobacteria growth indicator tube (MGIT) culture. Results of MGIT culture are considered gold standard.
Of the 173 specimens tested, MTB was detected in 48 (27.74%) samples by any of the above methods. Positivity in bronchoalveolar lavage was 31.4% (44/140) and in bronchial wash was 12.1% (4/33). Detection by microscopy, Xpert assay, and culture was 20 (11.56%), 45 (26.01%), and 38 (21.96%), respectively. Culture detected MTB in three additional specimens compared to Xpert assay. Xpert assay detected MTB in 45 (26%) specimens which include 10 specimens which were negative by culture. LPA detected MTB in 18 (90%) out of 20 smear-positive specimens. RIF resistance was detected in 20 (41.7%) specimens by Xpert and/or MGIT culture drug susceptibility testing (DST). Isoniazid (INH) resistance was detected in 19 specimens by LPA and MGIT culture DST.
Bronchoscopy can provide alternative respiratory specimens for diagnosing PTB in patients with difficulty to expectorate sputum. The utility of Xpert MTB/RIF as a rapid, sensitive, and specific test should always be supplemented with culture in difficult-to-obtain and precious respiratory specimens. LPA plays an important role in rapid detection of INH monoresistance.
对于无法咳出高质量痰液或痰液产生极少的患者，可以通过支气管镜采集标本。本研究的目的是确定在一家三级护理中心使用支气管镜采集标本，通过 Xpert MTB/RIF 检测和线探针检测（LPA）来诊断肺结核（PTB）。
TB 实验室收到的支气管镜标本通过显微镜检查、Xpert MTB/RIF 检测、LPA 和分枝杆菌生长指示管（MGIT）培养进行处理。MGIT 培养结果被认为是金标准。
在 173 个测试标本中，通过上述任何一种方法在 48 个（27.74%）标本中检测到 MTB。支气管肺泡灌洗液的阳性率为 31.4%（44/140），支气管冲洗液的阳性率为 12.1%（4/33）。显微镜检查、Xpert 检测和培养的阳性率分别为 20（11.56%）、45（26.01%）和 38（21.96%）。与 Xpert 检测相比，培养法在另外 3 个标本中检测到 MTB。Xpert 检测在 45 个（26%）标本中检测到 MTB，其中包括 10 个培养阴性的标本。LPA 在 20 个（90%）涂片阳性标本中检测到 MTB。Xpert 和/或 MGIT 培养药敏试验（DST）在 20 个（41.7%）标本中检测到 RIF 耐药。LPA 和 MGIT 培养 DST 在 19 个标本中检测到 INH 耐药。
支气管镜可为难以咳痰的患者提供替代的呼吸道标本来诊断 PTB。Xpert MTB/RIF 作为一种快速、敏感、特异的检测方法，在难以获得和珍贵的呼吸道标本中，应始终与培养法联合使用。LPA 在快速检测 INH 单耐药方面发挥着重要作用。
