半定量鲎试验测定支气管肺泡灌洗液中内毒素浓度诊断阴性菌肺炎

Determination of concentration of endotoxin in bronchoalveolar lavage fluid in the diagnosis of gram-negative pneumonia by semi-quantitative Limulus amebocyte lysate assay

目的为确定支气管肺泡灌洗液（BALF）中内毒素浓度增高诊断革兰阴性菌肺炎的准确性。方法对ICU内21例疑似肺部感染患者进行了28次BALF定量细菌培养、半定量鲎溶解物（LAL）试验和革兰染色检查。结果BALF中内毒素浓度≥1：16诊断阴性菌肺炎的敏感性为100．0％，特异性为88．9％。BALF中内毒素浓度增高与微生物学证实阴性菌肺炎之间呈良好诊断一致性（t＝9，87，P＜0.01）。BALF的革兰染色检出值与微生物学之间的一致性较差（t=1．19，P＞0．05）。结论结果提示，BALF中内毒素浓度≥1：16快速诊断阴性菌肺炎的准确性明显优于革兰染色检查，该方法有助于早期抗菌药物治疗的选择。

objective To determine the accuracy of elevated concentration of endotoxin in bronchoalveolar lavage fluid (BALF) in the diagnois of gram - negative pneumonia. Methods Quantitative culture, semi - quantitative endotoxin assay and Gram stain examination of BAL from twenty - one hospitalized adults in ICU with suspected lung infection were done for 28 times, Results A cutoff value of > 1: 16 for the concentration of endotoxin in BALF yielded the best concordance for the diagnosis of gram - negative pneumonia (sensitivity, 100%; specificity, 88. 9% ). Good diagnostic agreement was found between elevated concentration of endotoxin in BALF and microbiologically confirmed gram - negative pneumonia(t = 9. 87, P< 0. 01 ). Poor diagnostic agreement was observed between BALF Gram stain results and microbiologically confirmed gram - negative pneumonia (t = 1. 19, P > 0. 05 ). Conclusion The results suggest that the elevated concentration of endotoxin in BALF> 1: 16 is superior to Gram stain for the rapid identification of patients with gram - negative pneumonia, and this test helps early administration of antimicrobial treatment.