Tambyah P A, Halvorson K T, Maki D G
Department of Medicine, University of Wisconsin Medical School, University of Wisconsin, Madison, USA.
Mayo Clin Proc. 1999 Feb;74(2):131-6. doi: 10.4065/74.2.131.
To determine the pathogenesis of catheter-associated urinary tract infection (CAUTI) and the relative importance of each of the possible mechanisms of entry of infecting microorganisms to the catheterized urinary tract.
We conducted a prospective study of 1,497 newly catheterized patients. Paired quantitative urine cultures were obtained daily, from the catheter specimen port and from the collection bag, using a technique that could detect 1 colony-forming unit/mL. We assumed that with extraluminal infections, caused by microorganisms ascending from the perineum in the mucous film contiguous to the external surface of the catheter, the organisms would be detected first in bladder urine or in far higher concentrations in urine from the specimen port than from the collection bag. With intraluminal CAUTIs, caused by microorganisms gaining access to the catheter lumen because of failure of closed drainage or contamination of collection bag urine, the organisms would be detected first or in far larger numbers in a collection bag specimen.
The probable mechanism of infection could be determined for 173 of 250 organisms (69.2 %) identified in 235 new-onset CAUTIs. Among these 173 cases, 115 (66%) were extraluminally acquired, and 58 (34%) were derived from intraluminal contaminants. For these determinable cases, CAUTIs caused by gram-positive cocci (enterococci and staphylococci) and yeasts were far more likely to be extraluminally acquired (extraluminal:intraluminal, 2.9) than were gram-negative bacilli, which caused CAUTIs by both routes equally (extraluminal: intraluminal, 1.2; P = 0.007). Surprisingly, no significant differences were noted in pathogenetic mechanisms between men and women.
We conclude that, in both men and women, CAUTIs occur by both extraluminal and intraluminal portals of entry but derive preponderantly from organisms that gain access extraluminally. Strategies for prevention of CAUTIs must focus on new technologies to prevent access of organisms by all possible routes.
确定导尿管相关尿路感染（CAUTI）的发病机制以及感染微生物进入导尿尿路的每种可能机制的相对重要性。
我们对1497例新置入导尿管的患者进行了一项前瞻性研究。每天从导尿管标本端口和集尿袋中获取配对的定量尿培养物，采用能够检测到1个菌落形成单位/毫升的技术。我们假定，对于由微生物从会阴沿导尿管外表面相邻的粘膜膜向上蔓延引起的腔外感染，微生物首先会在膀胱尿液中被检测到，或者在来自标本端口的尿液中的浓度远高于来自集尿袋的尿液。对于由封闭引流失败或集尿袋尿液污染导致微生物进入导尿管腔引起的腔内CAUTI，微生物首先会在集尿袋标本中被检测到，或者数量远更多。
在235例新发CAUTI中鉴定出的250种微生物（69.2%）中的173种的感染可能机制可以确定。在这173例病例中，115例（66%）是腔外获得的，58例（34%）源自腔内污染物。对于这些可确定的病例，由革兰氏阳性球菌（肠球菌和葡萄球菌）和酵母菌引起的CAUTI远比革兰氏阴性杆菌更可能是腔外获得的（腔外：腔内，2.9），革兰氏阴性杆菌通过两种途径引起CAUTI的可能性相同（腔外：腔内，1.2；P = 0.007）。令人惊讶的是，男性和女性在发病机制上没有显著差异。
我们得出结论，在男性和女性中，CAUTI通过腔外和腔内进入途径发生，但主要源自腔外进入的微生物。预防CAUTI的策略必须侧重于新技术，以防止微生物通过所有可能途径进入。
