Division of Pulmonary Diseases, Geneva University Hospitals, Geneva, Switzerland.
Center for Clinical Research & Division of Clinical-Epidemiology, Department of Health and Community Medicine, University of Geneva, University Hospitals of Geneva, Geneva, Switzerland.
Front Cell Infect Microbiol. 2021 Aug 19;11:704169. doi: 10.3389/fcimb.2021.704169. eCollection 2021.
Diagnosis of (MTB) infection can be confirmed by Xpert assays within hours. However, when sample size does not allow performing both culture and Xpert, or if Xpert is negative, then formal diagnosis of MTB relies on culture and time to detection of growth (TDG) becomes critical for clinical management.
To determine TDG in Xpert negative samples, or in samples in which Xpert could not be performed, in a low-incidence area for MTB.
Retrospective analysis (2015-2020) of a database including all cultures for mycobacteria in a University Hospital covering approximately 500'000 inhabitants. Analysis was restricted to culture positive (C+) samples for MTB for which 1/Xpert was negative or could not be performed because of limited sample volume, and 2/collected from subjects treated less than 24 hours. TDG was analyzed according to microscopy, origin of sample (pulmonary or not) and presence of cavitation.
Among 837 C+ samples for MTB, 236 samples (80% of respiratory origin) from 147 patients fulfilled study criteria; 78 samples (49 patients, 33%) were acid-fast bacilli (AFB) positive. Median (IQR) TDG was 25 (17; 40) days for all samples. TDG exceeded 28 days in 43% of samples and was significantly shorter in AFB+ AFB- samples, and samples from cavitary non cavitary or extra-thoracic disease.
In Xpert negative samples, or samples for which Xpert could not be performed, TDG exceeded 4 weeks in 43% of samples. AFB+ and samples from cavitary lung disease had a significantly shorter TDG.
分枝杆菌（MTB）感染的诊断可在数小时内通过 Xpert 检测得到确认。然而，当样本量不足以同时进行培养和 Xpert 检测，或者 Xpert 检测结果为阴性时，MTB 的正式诊断依赖于培养，而检测到生长的时间（TDG）对于临床管理变得至关重要。
在 MTB 低发病率地区，确定 Xpert 检测结果为阴性的样本，或无法进行 Xpert 检测的样本的 TDG。
回顾性分析（2015-2020 年）了一家覆盖约 500000 居民的大学医院分枝杆菌培养的数据库，包括所有分枝杆菌培养结果。分析仅限于培养阳性（C+）的 MTB 样本，这些样本 1/Xpert 检测结果为阴性或由于样本量有限而无法进行 Xpert 检测，2/来自治疗时间少于 24 小时的患者。根据显微镜检查、样本来源（肺部或非肺部）和空洞存在情况分析 TDG。
在 837 例 MTB 的 C+培养样本中，147 例患者的 236 例（80%来自肺部）符合研究标准；78 例（49 例，33%）样本抗酸杆菌（AFB）阳性。所有样本的中位数（IQR）TDG 为 25（17；40）天。43%的样本 TDG 超过 28 天，AFB+和 AFB-样本、空洞性和非空洞性或胸外疾病样本的 TDG 明显较短。
在 Xpert 检测结果为阴性的样本或无法进行 Xpert 检测的样本中，43%的样本 TDG 超过 4 周。AFB+和空洞性肺病样本的 TDG 明显较短。
