机械通气病人气管内导管生物被膜的结构和病原学特征

Structural and pathogenic features of endotracheal tube biofilm in patients undergoing mechanical ventilation

目的 :确定机械通气病人气管内导管 (ETT)细菌生物被膜 (BF)形成的结构和病原学特征。方法 :前瞻性研究了 2 5支来自 2 2位平均插管 6 2 d(范围 1～ 16 9d)机械通气病人的拔除 ETT,扫描电镜 (SEM)和透射电镜 (TEM)用于检查 ETT- BF的结构特征 ,同时进行 ETT- BF定量细菌培养及耐药性检测。结果 :2 2支ETT(88% )分离出一系列微生物 ,包括革兰氏阴性杆菌、革兰氏阳性球菌和真菌 ,定量研究显示其密度可高达 4× 10 8cfu/ ml,铜绿假单胞菌在 1个管子内占优势而且存在于大部分 ETT中 ;SEM显示 EET(插管 >15 d)的内腔面覆盖一层融合的非结晶含菌基质 ,可见团状聚集的丛生细菌突出于管腔内 ;TEM显示在 ETT- BF广泛的基质中 ,散在分布着大量球菌和杆菌 ,在形态、大小和密度上有所不同 ,处于分裂相的细菌散布 BF全层 ,未发现核固缩现象 ;ETT- BF的累积呈现出一定的时间及重力相关过程。结论 :ETT内的细菌寄殖和

Objective: To determine the structural and pathogenic features of endotracheal tube biofilm (ETT BF) in patients undergoing mechanical ventilation. Methods: Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine BF in 25 ETT of extubation or change from 22 patients intubated for an average 62 days (rang1~169). ETT BF also were quantitatively cultured. Results: A range of microbial species, included gram negative bacilli, gram positive cocci and fungus, are isolated from 22 (88%) of 25 ETT. Quantitative bacterial counts can reach up to 4×10 8 cfu/ml. Pseudomonas aeruginosa is isolated with the highest count from one tube and present in the most of ETT. SEM show the inner surfaces of ETT (>15d) to be coated with confluent amorphous bacterium containing matrix. Some biofilm enclosed bacterial aggregates projected from the matrix into the lumen of the tube. TEM of BF sectional material shows large numbers of cocci and bacilli in a very extensive matrix. There are differences in shape, size and density of bacterium. The accumulation process of this BF layer is time related and gravity related. Conclusions: The ETT colonization and biofilm formation may be a significant factor in the pathogenesis of ventilator associated peneumonia (VAP).