A prospective study on the pathogenesis of catheter-associated bacteriuria in critically ill patients.

BACKGROUND:Updating the pathogenesis of catheter-associated bacteriuria (CA-bacteriuria) in the intensive care unit (ICU) is needed to adapt prevention strategies. Our aim was to determine whether the main pathway of CA-bacteriuria in ICU patients was endoluminal or exoluminal. In a prospective study, quantitative urine cultures were sampled from catheter sampling sites, collector bags and the catheter outer surface near the meatus from days 1 to 15 after catheterization. The endoluminal pathway was CA-bacteriuria (defined as 102 CFU/mL) first in collector bags and then in catheters. The exoluminal pathway was CA-bacteriuria first in catheters, on day 1 in early cases and after day 1 in late cases. RESULTS:Of 64 included patients, 20 had CA-bacteriuria. Means of catheterization days and incidence density were 6.81 days and 55.2/1000 catheter-days. Of 26 microorganisms identified, 12 (46.2%) were Gram positive cocci, 8 (30.8%) Gram negative bacilli and 6 yeasts. Three (11.5%) CA-bacteriuria were endoluminal and 23 (88.5%) exoluminal, of which 10 (38.5%) were early and 13 (50%) late. Molecular comparison confirmed culture findings. A quality audit showed good compliance with guidelines. CONCLUSION:The exoluminal pathway of CA-bacteriuria in ICU patients predominated and surprisingly occurred early despite good implementation of guidelines. This finding should be considered in guidelines for prevention of CA-bacteriuria.