Evaluation of Patients' Skin, Environmental Surfaces, and Urinary Catheters as Sources for Transmission of Urinary Pathogens

 

Background: Patients with urinary tract infection (UTI) or asymptomatic bacteriuria (ASB) are considered an important reservoir for transmission of urinary pathogens. However, there is limited information on the frequency of contamination of patients and their environment with urinary pathogens. 

Objective: To determine the frequency of skin and environmental contamination with urinary pathogens in patients with UTI or ASB and to test the hypothesis that presence of a urinary catheter is associated with increased contamination. 

Methods: We performed a prospective study of patients with bacteriuria (>10⁵ colony-forming units per mL) at 2 Cleveland hospitals from July through October, 2010. Sterile swabs were used to obtain cultures from skin, environmental surfaces, and urinary catheters (if present). Identification and susceptibility testing and molecular typing were performed to correlate organisms cultured from skin and environmental sites with concurrent urine isolates. Proportions of positive cultures were compared for patients with or without urinary catheters and for gram-negative versus gram-positive pathogens.

Results: Of 54 patients with bacteriuria, the mean age was 68 (range 25-96) and 34 (63%) had indwelling urinary catheters. Thirty-nine patients (72%) had gram-negative urinary pathogens (most commonly Klebsiella pneumoniae) and 16 had gram-positive pathogens (13 Enterococcus spp. and 3 Staphylococcus aureus). Contamination of skin sites, environmental sites, and the urinary catheter with organisms matching concurrent urine isolates occurred significantly more often for gram-positive versus gram-negative pathogens (P <0.006 for each comparison) (Figure). Frequencies of contamination did not differ significantly for patients with or without urinary catheters.

Conclusions: In patients with UTI or ASB, urinary pathogens frequently contaminate the skin, high-touch environmental surfaces, and urinary catheters. Contamination was significantly more common for gram-positive versus gram-negative pathogens. These sites may provide an important source for transmission of urinary pathogens.