Exposure to Mycobacterium tuberculosis during flexible bronchoscopy in patients with unexpected pulmonary tuberculosis

Objective: Recent guidelines recommend the use by healthcare personnel of a fit-tested N95 particulate respirator or higher-grade respiratory precaution in a patient undergoing bronchoscopy when pulmonary tuberculosis (PTB) is suspected. However, PTB may be unexpectedly diagnosed in this setting and therefore not evaluated, resulting in the unexpected exposure to Mycobacterium tuberculosis (MTB) of healthcare workers in the bronchoscopy suite. Here, we examined the incidence of unexpected exposure to MTB during flexible bronchoscopy and determined the exposure-related factors. Methods: Between 2011 and 2013, a retrospective study was conducted to evaluate unexpected diagnoses of PTB in the bronchoscopy suite. During the study period, 1650 consecutive patients for whom previous CT scans were available and who underwent bronchoscopy for respiratory disease other than PTB were included. The results of bronchial washing, bronchoalveolar lavage, and post-bronchoscopic sputum were reviewed. Results: PTB was unexpectedly diagnosed in 76 patients (4.6%). The presence of anthracofibrosis [odds ratio (OR), 3.878; 95% confidence interval (CI), 1.291–11.650; P = 0.016), bronchiectasis (OR, 1.974; 95% CI, 1.095–3.557; P = 0.024), or atelectasis (OR, 1.740; 95% CI, 1.010–2.903; P = 0.046) as seen on chest CT scan was independently associated with unexpected PTB. Patients with both anthracofibrosis and atelectasis were at much higher risk of unexpected PTB (OR, 4.606; 95% CI, 1.383–15.342; P = 0.013). Conclusions: The risk of MTB exposure by healthcare personnel in the bronchoscopy suite due to patients with undiagnosed PTB has been underestimated. Therefore, in geographic regions with an intermediate PTB prevalence, such as South Korea (97/100,000 persons per year), higher-grade respiratory precaution, such as a fit-tested N95 particulate respirator, should be considered to prevent occupational exposure to MTB during routine bronchoscopy, especially in patients with CT-confirmed anthracofibrosis, bronchiectasis, or atelectasis.

研究目的：现行临床指南建议，当怀疑患者罹患肺结核（pulmonary tuberculosis, PTB）时，医护人员在为其实施支气管镜检查时，需使用经适合性检验合格的N95颗粒物防护口罩（fit-tested N95 particulate respirator）或更高等级的呼吸道防护装备。然而，在该操作场景中，肺结核可能被意外确诊，导致术前未进行相关排查，进而使支气管镜检查室的医护人员意外暴露于结核分枝杆菌（Mycobacterium tuberculosis, MTB）。本研究旨在探讨柔性支气管镜检查期间意外暴露于MTB的发生率，并明确与暴露相关的危险因素。

研究方法：本研究为2011年至2013年间开展的回顾性研究，旨在评估支气管镜检查室中意外确诊的肺结核病例。研究期间，共纳入1650例连续入组患者，所有患者均具备既往胸部CT扫描资料，且因非肺结核类呼吸系统疾病接受支气管镜检查。本研究回顾分析了患者的支气管灌洗液、支气管肺泡灌洗液及支气管镜术后痰液的检测结果。

研究结果：共76例患者（占比4.6%）意外确诊为肺结核。胸部CT扫描显示存在炭末沉着性纤维化（odds ratio, OR=3.878；95%置信区间（confidence interval, CI）=1.291~11.650；P=0.016）、支气管扩张（OR=1.974；95%CI=1.095~3.557；P=0.024）或肺不张（OR=1.740；95%CI=1.010~2.903；P=0.046），与意外肺结核确诊独立相关。同时存在炭末沉着性纤维化与肺不张的患者，意外确诊肺结核的风险显著升高（OR=4.606；95%CI=1.383~15.342；P=0.013）。

研究结论：医护人员在支气管镜检查室中因未确诊肺结核患者而暴露于MTB的风险此前被低估。因此，在肺结核患病率中等的地理区域（如韩国，年患病率为97/10万），常规支气管镜检查期间，尤其是针对CT证实存在炭末沉着性纤维化、支气管扩张或肺不张的患者，应考虑采用更高等级的呼吸道防护措施，例如经适合性检验合格的N95颗粒物防护口罩，以预防医护人员发生职业性MTB暴露。