烧伤患者气管套管内鲍曼不动杆菌生物膜形成及特征研究

目的观察鲍曼不动杆菌在烧伤患者气管套管（ETT）内细菌生物膜（BF）的形成过程及其特征。方法烧伤患者ETT内壁取样（临床菌株）,Vitek2快速细菌自动鉴定仪分离鉴定9株鲍曼不动杆菌且均为泛耐药菌株。临床菌株分别于体外培养12、24、48、72h,改良微孔法进行BF半定量黏附试验;FITC-ConA/PI荧光双染色后激光扫描共聚焦显微镜（CLSM）观察并测定成熟BF厚度;以标准菌株鲍曼不动杆菌（ATCC19606）作为对照。于ETT拔除时收集并制备套管内壁标本,扫描电子显微镜观察。结果 BF半定量黏附试验结果显示,临床菌株黏附力在体外培养24～48h时达到高峰,且各时相点均显著大于标准菌株（P〈0.05）;CLSM动态观察发现,临床菌株在体外培养48h左右形成成熟BF,其厚度均显著大于标准菌株（P〈0.05）;ETT内壁扫描电镜观察可见成熟BF呈团状簇集,细菌被大量胞外多糖复合物包埋并融合呈片状。结论鲍曼不动杆菌能在烧伤患者ETT内壁形成BF,且具有成熟早、数量多、黏附能力强的特点,是烧伤后ETT相关感染的重要原因。

Formation and characteristics of Acinetobacter baumannii bacterial biofilm on inner surfaces of endotracheal tubes of burn patients

Objective To observe the formation and characteristics of Acinetobacter baumannii bacterial biofilm (BF) on inner surfaces of endotracheal tubes of burn patients. Methods Samples of clinical strains were obtained from inner surfaces of endotracheal tubes of burn patients, and 9 drug resistant Acinetobacter baumannii strains were isolated and identified by Vitek2 Automated Identification System. Clinical strains were cultured in vitro for 12, 24, 48 and 72 h, respectively, and modified microtiter-plate method was employed for semi-quantification test of BF formation. The thickness of mature BF of samples was determined by confocal laser scanning microscopy (CLSM) with FITC ConA/PI immunofluorescence double staining. Acinetobacter baumannii standard stains (ATCC19606) were served as controls. Meanwhile, samples of inner surfaces of endotracheal tubes were collected at tube withdrawal, and were also observed by scanning electron microscopy. Results Compared with standard strains, the adherence capabilities of clinical strains isolated from the tubes were much more enhanced （P<0.05）, and the peak time of adherence for all strains was at 24-48 h post culture. CLSM revealed that mature BF of clinical strains was formed after culture for 48 h, and was much thicker than that of the standard strains (P<0.05). SEM revealed that mature BF assembled in mass, and the bacteria were embedded in the matrix. Conclusion Acinetobacter baumannii strains can form BF on the inner surfaces of endotracheal tubes of burn patients with favorable characteristics, which is a major cause for endotracheal tube associated infection in burn patients.