Silver or nitrofurazone impregnation of urinary catheters has a minimal effect on uropathogen adherence.

PURPOSE: Bacterial adherence to the urinary catheter is an early step in biofilm formation and the pathogenesis of catheter associated urinary tract infection. We studied in vitro the effect of silver or nitrofurazone impregnation of urinary catheters on uropathogen ability to adhere to urinary catheters. MATERIALS AND METHODS: We studied commercially available nitrofurazone-silicone, silicone only, silver-silicone-hydrogel, silicone-hydrogel, silver-latex-hydrogel and latex-hydrogel catheters. Catheters were incubated in sterile broth for 0, 3, 5, 7 and 10 days, respectively, before inoculation and overnight incubation with Escherichia coli or Enterococcus faecalis. RESULTS: Adherence of E. coli and E. faecalis to nitrofurazone catheters was significantly decreased compared to that of silicone-only catheters when catheters were fresh. The anti-adherence effect of nitrofurazone on E. coli decreased with time but was still significant at 5 days. For E. faecalis the effect of nitrofurazone was lost by 3 days of pre-incubation. E. coli adherence was not significantly decreased on silver impregnated catheters compared to that on control catheters of the same base material. Silver was associated with a significant decrease in E. faecalis adherence to latex-hydrogel catheters but not to silicone-hydrogel catheters. The adherence of each species to silicone catheters with hydrogel was significantly lower than that to silicone-only control catheters. CONCLUSIONS: Silver impregnation had little effect on bacterial adherence in our model and nitrofurazone impregnation had a significant effect only for the first 5 days. Our results do not support a role for silver urinary catheters to prevent catheter associated urinary tract infection by decreasing bacterial adherence.

Inappropriate treatment of catheter-associated asymptomatic bacteriuria in a tertiary care hospital.

BACKGROUND: Evidence-based guidelines state that asymptomatic bacteriuria is not a clinically significant condition in men and nonpregnant women and that treatment is unlikely to confer clinical benefit. We hypothesized that, among patients with indwelling catheters or condom collection systems, many who receive a diagnosis of and are treated for catheter-associated urinary tract infection (CAUTI) actually have asymptomatic bacteriuria and, therefore, that antibiotic therapy is inappropriate. METHODS: We reviewed all urine culture results at a veterans affairs medical center during a 3-month period. Cultures yielding 10(4) colony-forming units/mL were included if the urine had been collected from a hospitalized patient with an indwelling (Foley) catheter or a condom collection system. We applied standardized definitions to determine whether the episode represented catheter-associated asymptomatic bacteriuria (CAABU) or CAUTI. Antibiotic therapy was considered appropriate for patients who met criteria for symptomatic UTI. RESULTS: Overall, 280 episodes met criteria for inclusion: 164 CAABU and 116 CAUTI. Of the 164 episodes of CAABU, 111 (68%) were managed appropriately (no treatment), whereas 53 (32%) were treated with antibiotics (inappropriate treatment). In multivariate analysis, older patient age, having predominantly gram-negative bacteriuria, and higher urine white blood cell count were significantly associated with inappropriate treatment of CAABU (P < .05, by logistic regression). CONCLUSIONS: Better recognition of CAABU and the distinction between this condition and CAUTI, consistent with evidence-based guidelines, may play a key role in reducing unneeded antibiotic usage in hospitalized patients.

Increased expression of type-1 fimbriae by nonpathogenic Escherichia coli 83972 results in an increased capacity for catheter adherence and bacterial interference.

BACKGROUND: In vitro, urinary catheter colonization by avirulent Escherichia coli 83972 impedes subsequent catheter colonization by a variety of uropathogenic organisms. However, E. coli 83972 shows a low efficacy of adherence to silicone urinary catheter material, possibly because the fim operon encoding adhesive type 1 fimbriae is incomplete. We hypothesized that improving the catheter adherence of E. coli 83972 would improve its bacterial interference properties. METHODS: We created adhesive mutants by transforming wild-type E. coli 83972 with fim(+) plasmids. Adherence to urinary catheters and ability to prevent uropathogenic E. coli from colonizing urinary catheters were studied by use of a sonication assay. RESULTS: The addition of a single-copy fim(+) plasmid increased adherence to urinary catheters 10-fold, and addition of an 18-copy fim(+) plasmid increased adherence 100-fold. The more adherent 18-copy fim(+) plasmid strain was more effective at blocking catheter colonization by pathogenic E. coli than was the wild-type parental strain. Neither Deltafim nor fim(+) E. coli 83972 adhered to shed urinary epithelial cells. CONCLUSIONS: Our results indicate that improving urinary catheter adherence augments the bacterial interference capabilities of benign E. coli 83972. Increased expression of type-1 fimbriae may enhance bacterial interference without conferring virulence on E. coli 83972.

Gram-negative intravascular catheter-related bacteremia in patients with spinal cord injury.

OBJECTIVE: To determine whether the prevalence of gram-negative catheter-related bloodstream infection (CRBSI) is higher in patients with spinal cord injury (SCI) than in patients without SCI. DESIGN: Retrospective chart review from August 1998 to August 2006. SETTING: A Veterans Affairs medical center, which serves as a tertiary care medical center to over 500 veterans with SCI and is the primary source of health care for veterans in southeast Texas. PARTICIPANTS: All hospitalized patients who had an International Classification of Diseases, Ninth Revision, code for bacteremia associated with their hospital stay. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: The proportion of CRBSI caused by gram-negative organisms in the SCI patients to the proportion of CRBSI caused by gram-negative organisms in the non-SCI patients. RESULTS: Eight (42%) of 19 episodes of CRBSI in the SCI were caused by a gram-negative organism as compared with 4 (11%) of 36 infections in the non-SCI group (P<.01). Factors associated with having a gram-negative organism rather than a gram-positive organism as the causative agent of CRBSI were SCI, femoral catheter site, prolonged hospitalization, decubitus ulcer, and urinary catheter. CONCLUSIONS: In our medical center, patients with SCI who develop CRBSI are more likely to have an infection with a gram-negative organism than are patients without SCI. This knowledge may guide initial empirical therapy of suspected bloodstream infection.