输尿管支架细菌生物膜观察及病原菌分布和耐药性

Pathogenic distribution and drug resistance of bacterial biofilm on ureteral stent

背景:输尿管支架被广泛用于肾盂输尿管交界处狭窄、原位尿流改道重建、输尿管或肾镜碎石、肾移植和肿瘤等泌尿系疾病,但长期留置输尿管支架可导致导管相关性尿路感染等并发症。目的:观察输尿管支架表面细菌生物膜的形态学特点,分析细菌生物膜的病原学分布特征及耐药性。方法:收集2016年1至12月重庆医科大学附属永川医院127例患者的输尿管支架标本,扫描电镜观察支架表面细菌生物膜的形态学特征,刚果红培养基分别筛选肾盂段、输尿管段和膀胱段支架的细菌生物膜菌株,同时进行尿培养,对检出的病原菌进行药敏试验分析。实验获得重庆医科大学附属永川医院伦理委员会批准,批准号:2014年科伦审22号。结果与结论:①在留置7,15,30d的输尿管支架表面均能够观察到细菌生物膜及数量不等的炎性附着物或结晶体,细菌生物膜的细菌被大量纤维膜包裹;留置7,15 d的输尿管支架表面可见呈片状散在分布的菌落,以杆菌为主;留置30 d的输尿管支架表面可见呈堆状分布的菌落,以球菌、杆菌为主;②127份输尿管支架标本中检出细菌生物膜106份,阳性率为83.5%,其中膀胱段阳性率最高,其次为肾盂段和输尿管段;尿培养阳性为25份,阳性率为19.7%,尿液培养的细菌生物膜阳性率明显低于输尿管支架培养结果(P<0.05);③106份阳性标本中检出细菌227株,其中革兰阴性菌株数显著高于革兰阳性菌株数(P<0.05);输尿管支架细菌生物膜和尿培养细菌均主要以大肠杆菌、铜绿假单胞菌、粪肠球菌和屎肠球菌最为常见;④输尿管支架管表面细菌生物膜菌株的耐药率高;⑤结果表明输尿管支架细菌生物膜是诱发导管相关性尿路感染的重要因素。

BACKGROUND: Ureteral stents have been extensively applied in the stenosis in the conjunction of the renal pelvis and ureter, the reconstruction of in situ urine flow, ureter or nephroscope lithotripsy, renal transplant, and tumors. However, the long-term retention of ureteral stents can induce catheter-associated urinary tract infection complications. OBJECTIVE: To investigate the morphological characteristics of bacterial biofilm on ureteral stent, and to analyze the features of pathogenic distribution and antimicrobial drug resistance to bacterial biofilm. METHODS: Specimens of ureteral stent were collected from 127 patients at Yongchuan Hospital, Chongqing Medical University between January and December 2016. The morphological characteristics of bacterial biofilm on the stent were observed under scanning electron microscope. Each specimen was divided into three parts(renal pelvis, ureter and bladder) for screening biofilm-forming bacteria strains separately by Congo red medium. The urine was bacterially cultured. Drug susceptibility test was done with the collected biofilm-forming bacteria strains. The study was approved by the Ethics Committee of Yongchuan Hospital, Chongqing Medical University(approval No. 201422). RESULTS AND CONCLUSION:(1) Bacterial biofilm was observed on the surface of ureteral stents at 7, 15 and 30 days of retention, with various numbers of inflammatory attachments or crystals. Bacteria on the bacterial biofilm were embraced by large amounts of fiber membranes. Patchy bacterial colonies were observed on the surface of the ureteral stent at 7 and 15 days of retention, which mainly focused on bacillus. Heap-shaped bacterial colonies were found on the surface of ureteral stents that were retained for 30 days, which mainly were bacillus and coccus.(2) A total of 106 bacterial biofilms were detected in the ureteral stent samples obtained from 127 pati ents. The positive rate was 83.5%, in which the bladder section had the highest positive rate, followed by the renal pelvis section and ureter section. There were 25 copies of positive urine culture, and the positive rate was 19.7%. The strains obtained from the bacterial biofilm on each section of the ureteral stents were significantly higher than that from the urine bacteria culture(P < 0.05).(3) A total of 227 strains were detected from 106 positive samples. Among these samples, the number of Gram-negative strains was significantly higher than that of Gram-positive strains(P < 0.05). Among culture bacteria of the bacterial biofilm on the ureteral stent and urine culture bacteria, colibacillus, pseudomonas aeruginosa, enterococcus faecalis and enterococcus faecium were the most common.(4) The biofilm-forming bacteria on the ureteral stent had a high drug resistance.(5) In summary, bacterial biofilm may be the important reason for catheter-associated urinary tract infection.