**2. Epidemiology**

Generally, UTIs comprise the 40% of hospital-acquired infections [5-9] and 80% of them are CAUTIs [10-11]. CAUTIs are directly related with the use of indwelling urinary cath‐ eters [12, 13]. Up to 25% of patients have an indwelling catheter placed at some time during their hospital stay [3]. CAUTIs are associated with increased morbidity, mortality, length of hospital stay and cost. It has been estimated that one episode of nosocomial ac‐ quired UTI adds 1–3 days of extra hospital stay [3]. Moreover, the annual cost of CAU‐ TIs is estimated to be \$340-370 million [14, 15].

© 2013 Efthimiou and Skrepetis; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The prevalence of nosocomial-acquired UTIs in Urology departments was estimated to be 10% in the Pan European Prevalence study and 14% in the Pan Euro Asian Prevalence study [16]. In the same study, the largest group was that of asymptomatic bacteriuria (29%) followed by cystitis (26%), pyelonephritis (21%), and urosepsis (12%). There were 0.61 catheters per patient. 51% of the catheters were transurethral with continuous drainage, 10% transurethral with open drainage, 2% clean intermittent catheterization, 11% suprapubic catheters, 12% nephrostomy tubes and 14% ureteral stents [16].

Origination of bacteria is from endogenous organisms either from rectum or colonizing the patient's perineum [23-25]. In one of these studies, colonization of periurethral area was more

Prevention of Catheter-Associated Urinary Tract Infections

http://dx.doi.org/10.5772/52957

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Bacteria adhere to catheters via a variety of molecules such are fibriae, heamagglutinin or capsular polysaccharide [26]. Once bacteria have attached to surfaces of catheters, they grow in glycocalyx-enclosed microcolonies and produce a biofilm on the catheter surface which is associated with CAUTIs [27]. Studies have shown that bacteria in this microenvironment are resistant to antibiotics for two reasons [28-30]. Firstly, they are metabolically inactive, perhaps due to low concentration of oxygen [28] and secondly, biofilm acts as a physical barrier to diffusion of antibiotics and host defense mechanisms [29-31]. On the contrary, planktonic-free floating bacteria in urine are susceptible to antibiotics [32-33]. It is worth noting that these two

Indwelling catheters not only act as a nidus for bacteria but they also cause physical trauma to normal urothelium, they may promote inflammatory reaction, alter metabolic activity and cell proliferation which facilitates bacterial infection [26]. Recently, an in vitro study which used bladder cancer cell cultures found that catheters are involved in disruption of bladder epithelial cell membranes as a result of physical abrasion which was followed by delayed

Figure 1 presents schematically all the possible mechanisms involved in pathogenesis of

The majority of uropathogens are fecal contaminants or skin residents from the patient's own native or transitory microflora that colonize the periurethral area. As it has already been mentioned CAUTIs caused by gram-positive cocci and yeasts are far more likely to be extraluminally acquired than were gram-negative bacilli, which caused CAUTIs by both routes

CAUTIs in short-term catheterization is usually produced by single species and *Escherichia coli* remains the most common infecting organism. However, a wide variety of other gram negative microorganisms may be isolated like *Klebsiela* spp., *Enterobacter* spp, and *Serratia* spp [35, 36]. Gram positive cocci including coagulase-negative staphylococci and *Enterococcus* spp have also been isolated [37, 38]. Other species commonly found in patients with short-term catheterization are *Proteus* spp. and *Morganella morganii* [37]. *Proteus mirabilis* is isolated more frequently than *E. coli* in men. Anaerobic organisms also contribute to infection [39]. Coloni‐ zation with methicillin-resistant *S. aureus* (MRSA) occurs frequently in institutions with endemic MRSA [40, 41]. Although initially biofilms contain single species of microbes, they

*P.aurignosa*, enterococci and *Candida* spp. are more commonly found in ICUs [17, 42]. *Provi‐ dencia stuartii* has been isolated in nursing home residents as a result of cross infection [43].

progressively become polimicrobic, especially in long term-catheterization [39].

prevalent in women than in men [23].

populations are not always identical.

**4. Microbiology of CAUTIs**

CAUTIs.

equally [23].

inflammation in response to bacterial infection [34].

Urinary catheters are responsible for nearly 97% of UTIs in ICUs [12, 13]. Recently published data, regarding device-associated infections within intensive care units (ICUs) collected by hospitals participating in the International Nosocomial Infection Control Consortium (INICC) between January 2003 and December 2008, showed an overall mean CAUTIs rate from 0.4 to 13.9 per 1000 urinary catheter-days [17]. The distribution was lower in the surgical-cardio‐ thoracic ICUs and higher in the Neurosurgical ICUs. Mean crude mortality and mean excess mortality rate for CAUTIs in ICUs were 32.9% and 18.5% respectively. Surgical-cardiothoracic and Neurosurgical ICUs had the highest urinary catheter utilization ratios (0.93 and 0.86 respectively). Pediatric ICUs had the lowest mean CAUTI and mean catheter utilization ratios (4.4 and 0.17 respectively) [17].

It has also been reported that 7.5% and 5.4% of nursing home residents in the USA and Europe respectively are long-term catheterized [18, 19]. Indwelling catheters in nursing home residents are used more commonly in men than in women with the most common indication that of urinary retention in men (87%) and in women (58%) [20]. In a web-based survey among nursing home residents, the percentage of residents with indwelling/suprapubic catheters and infections was 21.7% [21]. The overall incidence and prevalence of symptomatic UTs in the studied population were 29.2% and 1.64% respectively.
