Department of Critical Care, University of Pittsburgh, Pittsburgh, PA, USA.
Respir Care. 2009 Nov;54(11):1453-61.
Current strategies for diagnosing ventilator-associated pneumonia (VAP) favor the use of quantitative methods; however, semi-quantitative cultures of endotracheal aspirates are still commonly used.
The microbiological results of patients with suspected VAP who had both quantitative cultures with non-bronchoscopic bronchoalveolar lavage (BAL) and semi-quantitative cultures of endotracheal aspirate obtained within 24 hours of each other were retrospectively reviewed and compared, using a quantitative threshold of >or=10(4) colony-forming units/mL as a reference standard.
256 patients with paired cultures were identified. Concordance between endotracheal aspirate (any growth of pathogens) and non-bronchoscopic BAL was complete in 58.2% and completely discordant in 23.8%. The sensitivity and specificity of endotracheal aspirate were 65.4% and 56.1%, which improved to 81.2% and 61.9% when antibiotic management decisions were considered in the analysis. Twenty-six patients had endotracheal aspirate cultures that were falsely negative for pathogens, with 61.5% of these patients demonstrating growth of non-fermenting Gram-negative rods or methicillin-resistant Staphylococcus aureus (MRSA) on non-bronchoscopic BAL. Overall, 45 patients (17.5%) among the entire cohort had false positive endotracheal aspirate cultures, with 19 of these patients (42.2%) demonstrating growth of non-fermenting Gram-negative rods or MRSA.
Semi-quantitative cultures of endotracheal aspirate are poorly concordant with quantitative cultures obtained via non-bronchoscopic BAL. Although the performance of endotracheal aspirate improves when antibiotic treatment is considered, guiding therapy on the basis of semi-quantitative cultures may still result in failure to identify potentially multiple-drug-resistant pathogens, and would also tend to promote excessive antibiotic usage. Our data support the use of quantitative cultures in diagnosing VAP.
目前诊断呼吸机相关性肺炎（VAP）的策略倾向于使用定量方法；然而，气管内抽吸的半定量培养仍被广泛应用。
回顾性分析了 256 例在 24 小时内同时进行定量培养（非支气管镜肺泡灌洗（BAL））和气管内抽吸半定量培养的疑似 VAP 患者的微生物学结果，并以定量阈值 >或=10(4) 个菌落形成单位/ml 作为参考标准进行比较。
共确定了 256 例配对培养患者。气管内抽吸物（任何病原体生长）与非支气管镜 BAL 完全一致的比例为 58.2%，完全不一致的比例为 23.8%。气管内抽吸的敏感性和特异性分别为 65.4%和 56.1%，当分析中考虑抗生素管理决策时，其敏感性和特异性分别提高至 81.2%和 61.9%。26 例患者的气管内抽吸物培养结果对病原体呈假阴性，其中 61.5%的患者在非支气管镜 BAL 中表现为非发酵革兰氏阴性杆菌或耐甲氧西林金黄色葡萄球菌（MRSA）生长。总的来说，整个队列中有 45 例（17.5%）患者的气管内抽吸物培养结果为假阳性，其中 19 例（42.2%）患者表现为非发酵革兰氏阴性杆菌或 MRSA 生长。
气管内抽吸的半定量培养与非支气管镜 BAL 获得的定量培养结果一致性较差。尽管在考虑抗生素治疗时，气管内抽吸的表现有所改善，但基于半定量培养来指导治疗可能仍然无法识别潜在的多种耐药病原体，并且还可能导致过度使用抗生素。我们的数据支持使用定量培养来诊断 VAP。
