Objectives This study aimed to determine whether collecting a lower respiratory tract sample (LRTS) for bacterial microscopy, culture, and resistance (MCR) testing affects outcomes in patients with CAP. Methods A cohort study including adults admitted to hospital with CAP. The primary outcome was the duration of narrow-spectrum antibiotic treatment. Secondary outcomes included intravenous and total antibiotic durations, time to discharge, and 90-day mortality. Propensity score matching (PSM) balanced covariates between those who did and did not have an LRTS taken. Subgroup analyses focused on CAP due to Streptococcus pneumoniae or Haemophilus influenzae. Results After PSM, the cohort consisted of 1,434 patients. LRTS collection did not impact narrow-spectrum antibiotic use but was associated with longer intravenous (0.6 days longer, p=0.001) and total antibiotic treatments (10.4 vs 9.9 days, p=0.036). Time-to-event analysis showed lower probability of early discharge for those with an LRTS (HR 0.88, 95%CI 0.79-0.98) and higher probability for those with CAP due to S. pneumoniae or H. influenzae (HR 1.44, 95%CI 1.22-1.71). Survival analysis showed lower 90-day mortality for patients with an LRTS (HR 0.78, 95%CI 0.61-0.99) and for those with CAP due to S. pneumoniae or H. influenzae (HR 0.38, 95%CI 0.24-0.62). Conclusions LRTS collection did not directly affect the use of narrow-spectrum antibiotics but was associated with extended antibiotic treatments overall. Additionally, LRTS collection was linked to longer hospital stays and reduced mortality. Until more sensitive methods for determining CAP aetiology become available, LRTS MCR testing should remain a standard investigation for patients admitted with CAP.

中文翻译：

---

下呼吸道样本培养对社区获得性肺炎结局的影响：一项倾向评分匹配的队列研究


目的 本研究旨在确定收集下呼吸道样本 （LRTS） 进行细菌显微镜检查、培养和耐药性 （MCR） 检测是否会影响 CAP 患者的预后。方法 一项队列研究，包括因 CAP 入院的成年人。主要结局是窄谱抗生素治疗的持续时间。次要结局包括静脉注射和总抗生素持续时间、出院时间和 90 天死亡率。倾向得分匹配 （PSM） 平衡了参加和未参加 LRTS 的人之间的协变量。亚组分析侧重于肺炎链球菌或流感嗜血杆菌引起的 CAP。结果 PSM 后，该队列由 1,434 例患者组成。LRTS 收集不会影响窄谱抗生素的使用，但与静脉注射时间延长 （延长 0.6 天，p=0.001） 和总抗生素治疗 （10.4 天 vs 9.9 天，p=0.036） 相关。事件发生时间分析显示，LRTS 患者提前出院的可能性较低 （HR 0.88,95% CI 0.79-0.98），而肺炎链球菌或流感嗜血杆菌引起的 CAP 患者的可能性较高 （HR 1.44,95%CI 1.22-1.71）。生存分析显示，LRTS 患者 （HR 0.78,95% CI 0.61-0.99） 和肺炎链球菌或流感嗜血杆菌引起的 CAP 患者 （HR 0.38,95% CI 0.24-0.62） 的 90 天死亡率较低。结论 LRTS 收集不直接影响窄谱抗生素的使用，但总体上与延长抗生素治疗相关。此外，LRTS 收集与更长的住院时间和降低死亡率有关。在确定 CAP 病因的更敏感方法可用之前，LRTS MCR 检测应仍是 CAP 入院患者的标准检查。