Sputum pathogen spectrum and clinical outcomes of upper respiratory tract infection in bronchiectasis exacerbation: a prospective cohort study

Upper respiratory tract infection (URTI) is common in humans. We sought to profile sputum pathogen spectrum and impact of URTI on acute exacerbation of bronchiectasis (AE). Between March 2017 and December 2021, we prospectively collected sputum from adults with bronchiectasis. We stratified AEs into events related (URTI-AE) and unrelated to URTI (non-URTI-AE). We captured URTI without onset of AE (URTI-non-AE). We did bacterial culture and viral detection with polymerase chain reaction, and explored the pathogen spectrum and clinical impacts of URTI-AE via longitudinal follow-up. Finally, we collected 479 non-AE samples (113 collected at URTI-non-AE and 225 collected at clinically stable) and 170 AE samples (89 collected at URTI-AE and 81 collect at non-URTI-AE). The viral detection rate was significantly higher in URTI-AE (46.1%) than in non-URTI-AE (4.9%) and URTI-non-AE (11.5%) (both <i>P </i>&lt; 0.01). Rhinovirus [odds ratio (OR): 5.00, 95% confidence interval (95%CI): 1.06–23.56, <i>P </i>= 0.03] detection was independently associated with URTI-AE compared with non-URTI-AE. URTI-AE tended to yield higher viral load and detection rate of rhinovirus, metapneumovirus and bacterial shifting compared with URTI-non-AE. URTI-AE was associated with higher initial viral loads (esp. rhinovirus, metapneumovirus), greater symptom burden (higher scores of three validated questionnaires) and prolonged recovery compared to those without. Having experienced URTI-AE predicted a greater risk of future URTI-AE (OR: 10.90, 95%CI: 3.60–33.05). In summary, URTI is associated with a distinct pathogen spectrum and aggravates bronchiectasis exacerbation, providing the scientific rationale for the prevention of URTI to hinder bronchiectasis progression.

上呼吸道感染（Upper Respiratory Tract Infection, URTI）在人群中十分常见。本研究旨在明确痰液病原体谱，以及URTI对支气管扩张急性加重（acute exacerbation of bronchiectasis, AE）的影响。研究于2017年3月至2021年12月期间，前瞻性收集支气管扩张成人患者的痰液样本。我们将AE分为与URTI相关的发作（URTI-AE）及与URTI无关的发作（non-URTI-AE），同时纳入未发生AE的URTI患者样本（URTI-non-AE）。本研究采用细菌培养与聚合酶链反应（polymerase chain reaction, PCR）开展病毒检测，并通过纵向随访分析URTI-AE的病原体谱及临床影响。最终共纳入479份非AE样本（其中113份来自URTI-non-AE患者，225份来自临床稳定期患者）及170份AE样本（其中89份来自URTI-AE患者，81份来自non-URTI-AE发作期患者）。URTI-AE组的病毒检出率（46.1%）显著高于non-URTI-AE组（4.9%）与URTI-non-AE组（11.5%），组间差异均具有统计学意义（均P<0.01）。以non-URTI-AE为对照，鼻病毒（rhinovirus）检出与URTI-AE独立相关（比值比（odds ratio, OR）=5.00，95%置信区间（95% confidence interval, 95%CI）=1.06~23.56，P=0.03）。与URTI-non-AE组相比，URTI-AE组的病毒载量、鼻病毒与偏肺病毒（metapneumovirus）的检出率以及细菌移位情况均更为显著。与未发生URTI-AE的患者相比，URTI-AE患者的初始病毒载量（尤其是鼻病毒、偏肺病毒载量）更高、症状负荷更重（三份经验证的问卷评分均更高）且恢复时间更长。既往发生过URTI-AE的患者未来再次发生URTI-AE的风险更高（OR=10.90，95%CI=3.60~33.05）。综上，URTI与特征性的病原体谱相关，且可加重支气管扩张急性加重，这为通过预防URTI以延缓支气管扩张病情进展提供了科学依据。