Miller M A, Prior R B, Horvath F J, Hjelle J T
Department of Basic Sciences, University of Illinois College of Medicine, Peoria 61656.
Am J Kidney Dis. 1990 Feb;15(2):117-22. doi: 10.1016/s0272-6386(12)80508-7.
Urinary tract infections (UTI) due to gram-negative bacteria are a serious complication in patients with polycystic kidney disease (PKD). Endotoxin, a component of the cell wall of gram-negative bacteria, has been reported to be pro-cystogenic in experimental animals. Because endotoxin levels in urines (endotoxiuria) from PKD patients have not been reported, the Limulus amebocyte lysate (LAL) assay, which detects picogram quantities of endotoxin, was used to probe for this cyst-promoting chemical. Fifteen PKD patients (seven females, eight males), asymptomatic for UTI, were tested and compared with 10 female and 10 male controls. All urines were assessed for (1) evidence of aerobic bacteria by routine quantitative cultures, (2) bacteria and pyuria by microscopic examination of gram-stained urine, and (3) bacterial endotoxin by the LAL assay. LAL tests were positive in 73% (11/15) of PKD patients, but only 25% (5/20) of controls (P = 0.0058). There was no significant difference in test positivity between PKD females (71%) and males (75%). There was no correlation of age, degree of renal dysfunction, or urine osmolality with endotoxiuria. Routine quantitative cultures were negative for gram-negative bacteria in PKD patients and all controls (except one female), as were microscopic findings for intact bacteria and pyuria. Thus endotoxiuria, in the absence of classical signs, symptoms, and microbiological findings of UTI, raises the possibility that endotoxin is available intrarenally to promote cystogenesis even before a potential susceptibility of PKD patients to classical UTI is manifested. Sources of urinary endotoxin observed in PKD patients, such as cryptic intrarenal sites or leakage from the gastrointestinal (GI) tract, remain to be defined.
革兰氏阴性菌引起的尿路感染（UTI）是多囊肾病（PKD）患者的一种严重并发症。内毒素是革兰氏阴性菌细胞壁的一种成分，据报道在实验动物中具有促囊肿形成作用。由于尚未有关于PKD患者尿液中内毒素水平（内毒素尿）的报道，因此采用能检测皮克量内毒素的鲎试剂（LAL）检测法来探寻这种促进囊肿形成的化学物质。对15例无UTI症状的PKD患者（7名女性，8名男性）进行了检测，并与10名女性和10名男性对照者进行比较。对所有尿液进行了以下评估：（1）通过常规定量培养检测需氧菌；（2）通过革兰氏染色尿液显微镜检查检测细菌和脓尿；（3）通过LAL检测法检测细菌内毒素。LAL检测在73%（11/15）的PKD患者中呈阳性，但在对照者中仅为25%（5/20）（P = 0.0058）。PKD女性（71%）和男性（75%）之间的检测阳性率无显著差异。年龄、肾功能不全程度或尿渗透压与内毒素尿之间无相关性。PKD患者和所有对照者（除一名女性外）的常规定量培养结果显示革兰氏阴性菌均为阴性，完整细菌和脓尿的显微镜检查结果也是如此。因此，在没有UTI的典型体征、症状和微生物学检查结果的情况下，内毒素尿增加了一种可能性，即甚至在PKD患者表现出对经典UTI的潜在易感性之前，内毒素就可在肾脏内发挥作用促进囊肿形成。PKD患者中观察到的尿液内毒素来源，如隐匿的肾内部位或胃肠道（GI）道渗漏，仍有待确定。
