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

Abstract

BACKGROUNDCatheterization facilitates continuous bacteriuria, for which the clinical significance remains unclear. This study aimed to determine the clinical presentation, epidemiology, and dynamics of bacteriuria in a cohort of long-term catheterized nursing home residents.METHODSProspective urine culture, urinalysis, chart review, and assessment of signs and symptoms of infection were performed weekly for 19 study participants over 7 months. All bacteria ≥ 1 × 103 cfu/mL were cultured, isolated, identified, and tested for susceptibility to select antimicrobials.RESULTSIn total, 226 of the 234 urine samples were polymicrobial (97%), with an average of 4.7 isolates per weekly specimen. A total of 228 urine samples (97%) exhibited ≥ 1 × 106 CFU/mL, 220 (94%) exhibited abnormal urinalysis, 126 (54%) were associated with at least 1 possible sign or symptom of infection, and 82 (35%) would potentially meet a standardized definition of catheter-associated urinary tract infection (CAUTI), but only 3 had a caregiver diagnosis of CAUTI. Bacterial isolates (286; 30%) were resistant to a tested antimicrobial agent, and bacteriuria composition was remarkably stable despite a combined total of 54 catheter changes and 23 weeks of antimicrobial use.CONCLUSIONBacteriuria composition was largely polymicrobial, including persistent colonization by organisms previously considered to be urine culture contaminants. Neither antimicrobial use nor catheter changes sterilized the urine, at most resulting in transient reductions in bacterial burden followed by new acquisition of resistant isolates. Thus, this patient population exhibits a high prevalence of bacteriuria coupled with potential indicators of infection, necessitating further exploration to identify sensitive markers of true infection.FUNDINGThis work was supported by the NIH (R00 DK105205, R01 DK123158, UL1 TR001412).

Keywords: Bacterial infections; Infectious disease; Medical devices; Microbiology; UTI/pyelonephritis.

Figure 1. Epidemiology and dynamics of catheter-associated bacteriuria.

The complete longitudinal data for 4 study participants (letters) at each study visit (numbers, starting with 0 for baseline) are presented. The first row of pie charts displays the bacterial species that were identified by standard culture methods at each visit, the second row displays the urinalysis test strip results, and the third row displays the potential signs and symptoms of infection that were present at each study visit. White circles with black outlines indicate study visits at which assessments were negative, while empty spaces indicate study visits at which a particular assessment could not be made. Brackets indicate a caregiver-diagnosed CAUTI, asterisks indicate antimicrobial use, and the ^ symbol indicates when the participant’s catheter was changed. Misc, Gram⁺ bacteria that were PYR^–Catalase^–Streptex^–; MSSA, methicillin-sensitive Staphylococcus aureus; MRSA, methicillin-resistant Staphylococcus aureus; CNS, coagulase^– Staphylococcus; Pseudomonas other, Gram^– bacteria with good identification to genus via API-20E but were not P. aeruginosa by PCR; Other, any Gram^– organism that could not be identified by API-20E.

Figure 2. Impact of catheter changes and antibiotic use on colonization density.

The total number of unique bacterial species isolated from each weekly urine sample (0–10 species) are displayed for all study participants (A–S) across each study visit (0–30 visits). Symbol color indicates whether an event occurred since the prior visit that could impact colonization density.