Prospective assessment of catheter-associated bacteriuria in nursing home residents: clinical presentation, epidemiology, and colonization dynamics

Background: Long-term catheterization facilitates continuous bacteriuria, for which the clinical significance is unclear. The objectives of this study were to determine the clinical presentation, epidemiology, and dynamics of bacteriuria in a cohort of catheterized nursing home residents. Methods: Prospective weekly urine collection, culture, urinalysis, chart review, and assessment of possible signs and symptoms of infection for 19 study participants over 260 weeks. All bacteria ≥103 cfu/ml were isolated, identified, and subjected to select antimicrobial testing. Results: From 234 urine samples, 1,092 bacteria were isolated and 286 (26%) were resistant to a tested antimicrobial. 226 urines were polymicrobial (97%), with an average of 4.7 isolates per weekly specimen. 233 urines (99%) exhibited >103 CFU/ml, 220 (94%) exhibited abnormal urinalysis, 77 (33%) were associated with at least one sign or symptom of infection, 51 (22%) met a standardized definition of CAUTI, and 3 (1%) had a corresponding caregiver diagnosis of CAUTI. Bacteriuria composition was remarkably stable, but catheter changes and antimicrobial treatment resulted in a net increase of 1.9 and 0.3 isolates per participant, respectively, and represented a source of new acquisition of antimicrobial resistant bacteria. Conclusions: Catheterized individuals exhibit a high baseline prevalence of bacteriuria involving pathogenic bacteria and potential indicators of infection. Bacteriuria composition is largely polymicrobial and stable, and includes organisms previously considered to be urine culture contaminants. However, catheter changes and antimicrobial treatment may do more harm than good in this patient population. Funding: This work was supported by the NIH (R00 DK105205, R01 DK123158, UL1 TR001412)