经尿道留置膀胱异物并注射产超广谱β-内酰胺酶大肠埃希菌建立尿路感染大鼠模型

A non-surgical rat model of foreign body-associated urinary tract infection with ESBLs-producing E.coli injection

目的目前传统尿路感染模型操作过程复杂、易于感染,而单纯经尿道注射细菌模型又不够稳定。文章探究采用经尿道留置膀胱异物加注射产超广谱β-内酰胺酶(ESBLs)大肠埃希菌的方法建立尿路感染大鼠模型的可行性。方法SD大鼠随机数字表法分为空白组,无异物7、14 d组,异物7、14 d组。异物组经尿道置入异物加注射产ESBLs大肠埃希菌菌液,无异物和空白组分别注入等量菌液和无菌等渗盐水。检测双侧肾重指数、血液白细胞及中性粒计数、尿液及肾细菌学和病理学变化。结果与空白组左、右肾重指数[(32.13±1.10)×10^(-2),(32.18±0.90)×10^(-2)]比较,异物7 d组左、右肾重指数[(42.83±1.43)×10^(-2),(41.28±1.55)×10^(-2)]增加(P<0.01),异物14 d组左、右肾重指数[(38.15±1.40)×10^(-2),(39.10±3.01)×10^(-2)]增加(P<0.01);与无异物7d组比较,异物7d组左、右肾重指数增加[(31.08±0.91)×10^(-2)vs (42.83±1.43)×10^(-2),(31.62±0.81)×10^(-2)vs (41.28±1.55)×10^(-2),P<0.01];与无异物14 d组比较,异物14 d组左、右肾重指数均增加[(32.97±0.64)×10^(-2)vs(38.15±1.40)×10^(-2),(33.17±0.27)×10^(-2)vs (39.10±3.01)×10^(-2),P<0.01]。空白组、无异物14d组肾及尿液均未培养出细菌;无异物7 d组尿液细菌培养(阳性率33.3%)、肾未培养出细菌;异物7、14 d组肾及尿液细菌培养,阳性率100%。异物组肾及尿液细菌培养计数结果:肾和尿液7 d培养计数分为106CFU/g、107CFU/mL,14 d培养计数分为103CFU/g、106CFU/mL。与空白组比较,异物7 d组白细胞总数升高(P<0.05),异物7 d组、异物14 d组中性粒百分率升高(P<0.01)。与无异物7 d组比较,异物7 d组白细胞总数、中性粒百分率升高(P<0.05);与无异物14 d组比较,异物14 d组中性粒百分率升高(P<0.01)。异物7 d组上皮细胞有严重的水肿和大量炎症细胞浸润、黏膜下细菌菌落、少许上皮细胞脱落,异物14 d组上皮细胞连续性完全中断、大量的上皮细胞脱落及炎症细胞浸润,黏膜下成团的细菌菌落。镜下肾HE染色:异物7 d组广泛的肾盏黏膜充血、水肿,黏膜下小脓肿、出血,大量炎症细胞浸润,肾小管部分上皮细胞坏死脱落;异物14 d组肾盏有炎症改变,肾小管萎缩、扩张、坏死脱落等管型改变,部分肾小球形态改变及周围少许纤维组织形成。结论经尿道留置膀胱异物加注射产ESBLS大肠埃希菌可建立高成功率、稳定的尿路感染大鼠模型。

Objective At present,the traditional model of urinary tract infection is not only complex in operation process but also easy to be infected,and the model with simple transurethral bacterial injection is not stable enough.This study established a rat model of foreign body-associated urinary tract infection.A spiral polyethylene tube(PT)was placed transurethrally into the bladder by transurethral inoculation with extended-spectrumβ-lactamases-producing Escherichia coli(ESBLs E.coli). Methods SD female rats were randomly divided into blank control group,no foreign body groups at 7 d and 14 d,foreign body groups at 7 d and 14 d.ESBLs E.coli was injected transurethrally by foreign body into the bladder in foreign body groups.The same volumes of ESBLs E.coli and sterile saline were injected respectively in no foreign body and blank groups.Examination was made on bilateral renal gravity index,the numbers of white blood cells and neutrophils,the bacteriological and pathological changes in urine and kidney. Results The bilateral renal gravity index,the percentage of neutrophils and and the positive rates of renal and urine bacteria culture in foreign body groups at 7 d and 14 d were significantly higher than those in blank control group and no foreign body groups(P<0.05).The number of white blood cells in foreign body group at 7 d was significantly higher than those of blank control and no foreign body group(P<0.05).The positive rates of renal and urine bacteria culture were 100%in the foreign body groups at 7 d and 14 d.The positive rate of urine bacteria culture in no foreign body at 7 d was 33.3%.Under the light microscope,there were inflammatory changes in the kidney and bladder tissues of the rats in foreign body groups,and a few fibrous tissues were formed around glomeruli in foreign body group at 14 d. Conclusion The establishment of a highly successful and stable rat model of urinary tract infection can be successfully achieved by injection of ESBLS E.coli through transurethral foreign body placed in bladder.