Complicated Catheter-Associated Urinary Tract Infections Due toEscherichia coliandProteus mirabilis

Abstract

SUMMARY Catheter-associated urinary tract infections (CAUTIs) represent the most common type of nosocomial infection and are a major health concern due to the complications and frequent recurrence. These infections are often caused by Escherichia coli and Proteus mirabilis. Gram-negative bacterial species that cause CAUTIs express a number of virulence factors associated with adhesion, motility, biofilm formation, immunoavoidance, and nutrient acquisition as well as factors that cause damage to the host. These infections can be reduced by limiting catheter usage and ensuring that health care professionals correctly use closed-system Foley catheters. A number of novel approaches such as condom and suprapubic catheters, intermittent catheterization, new surfaces, catheters with antimicrobial agents, and probiotics have thus far met with limited success. While the diagnosis of symptomatic versus asymptomatic CAUTIs may be a contentious issue, it is generally agreed that once a catheterized patient is believed to have a symptomatic urinary tract infection, the catheter is removed if possible due to the high rate of relapse. Research focusing on the pathogenesis of CAUTIs will lead to a better understanding of the disease process and will subsequently lead to the development of new diagnosis, prevention, and treatment options.

Evaluation of pathogenicity islands in uropathogenic Escherichia coli isolated from patients with urinary catheters

“…Over one million cases of CAUTIs are reported annually, and CAUTIs account for about 80% of all nosocomial UTIs cases [3]. Escherichia coli is the most common cause of UTIs, accounting for 80%-90% of all UTIs seen among outpatients [4].…”

Implementing an evidence-based practice protocol for prevention of catheterized associated urinary tract infections in a progressive care unit

“…The use of indwelling urethral catheters should be limited to preoperative use for surgical procedures, urine output monitoring in critically ill patients, acute urinary retention, and to assist in pressure ulcer healing for incontinent patients [2] . In 2009, the Center for Disease Control (CDC) listed recommendations for appropriate use, and the examples given were consistent with those of Jacobsen.…”

“…Symptoms of a UTI can range from mild (fever, urethritis, and cystitis) to severe (renal scarring, acute pyelonephritis, and bacteremia). Left untreated, these infections can lead to urosepsis and death [2] . These infections are painful for patients and costly for hospitals due to increased length of stay and use of additional resources.…”

Catheter –Associated Urinary Tract Infection, Management, And Preventions

“…In the mouse model of UTI, inoculation of E.coli into bladder is followed by invasion of the superficial bladder cells and the formation of intracellular bacterial colonies that, in response to infection, exfoliate and are removed with the flow of urine [17].To avoid clearance of exfoliation, these intracellular uropathogens can reemerge and establisha persistent, quiescent bacterial reservoir within the bladder mucosa that may serve as a source for recurrent acute infections [17].Although internalization of uropathogenicE, coli into bladder and renal epithelial cells been observed in vitro and in vivo, there is only sparse evidence that intracellular bacterial colonies observed in mouse occur in humans [18,19].and only indirect evidence that intracellular bacterial colonies observed in mouse occur in humans [20].It is possible that invasion of uropathogens into uroepthelial cells is the trigger for urinary symptoms since pyuria often accompanies ASB in both catheterized and noncatheterized patients [1].Strains of E.coli associated with symptomatic lower or upper tract infection in healthy hosts are more likely to have certain putative virulence determinants such as P fimbriae, composed with colonic strains and those causing ASB .However, many symptomatic UTIs are caused by E. Coli with evidence profile similar to that in strains causing ASB, and these putative virulence factors can be found in strains causing ASB, or in colonic flora [21,22].…”

“…facilitates ascension of uropathogens from the meatus to the bladder the catheter -mucosa interface, provides a pool of organisms in the drainage bag, if the closed system is not maintained. Which can ascendintraluminally to the bladder, compromises complete voiding and constitutes a frequently manipulated foreign body on which pathogens are deposited via the hands of personnel.Indwelling catheter provide a surface for the attachment of host binding receptors that are recognized by bacterial adhesins, thus enhancing microbial adhesion, as well as disrupting the uroepithelial mucosa to expose new binding sites for bacterial adhesions [19].Bacteria attached to the catheter surface form exopolysaccharides that entrap bacteria, which replicate and form microcolonies that mature into biofilms on the inner and outer surfaces of the catheter [19].These biofilms protect uropathogens from antibiotics and the host immune response and facilitate transfer of antibiotic resistant genes [19].Some uropathogens in biofilms,such as Proteus sp., have the ability to hydrolyze urea to free ammonia and rise the urinary pH ,with precipitation of minerals such ashydroxyapatite or struvite creating encrustatation that can block catheter flow [27,19].The source of uropathogens in catheterized patients includes patients' endogenous flora, health care personnel, or inanimate objects [27].Not unexpectedlyuro pathogen virulence determinants such P fimbriae appear to be of less importance in pathogenesis of nosocomial UTIs compared with uncomplicated UTIs [22].Approximately two thirds(79% for gram-positive cocci and 54% gram-neagative bacilli) of the uropathogens causing CAbacteriuria in patients with in dwellimguretheral catheters are extraluminally acquired(ascension along catheteruretheral mucosa interface) and one third are intraluminally acquired ,although in some trials the proportion of strains originating from the drainage bag is much less, Rectal and periuretheral colonization with the infecting strain often precedes CA-bacteriuria, especially in women [28,29].The relative importance of the intraluminal pathway has much to do the frequency with which closed drainage systems are breached, which has been shown to be associated with UTI. The negative impact of the catheter is demonstrated by the finding that despite the continuous drainage of urine through the catheter,in patients with catheter urine colony count as low as 3 to 4 CFU/ml who are not given antibiotics, the level of bacteriuria or candiduriauniformaly rises to greater than 10 5 CFU/ml,within 24 to 48 hours in those who remain catheterized [30].…”