Clinical Urinary Tract Infections in Kidney Transplant Recipients With Initially Asymptomatic Bacteriuria: A Single-Center Retrospective Cohort Study

Abstract

Rationale & Objective

Management of asymptomatic bacteriuria in kidney transplant recipients remains uncertain. Our main objective was to evaluate whether patient- or episode-related factors could help identify episodes of asymptomatic bacteriuria associated with a higher risk of being followed by a symptomatic urinary tract infection.

Study Design

A single-center, retrospective cohort study.

Settings & Participants

Consecutive patients who received a kidney transplantation between January 1, 2008, and April 26, 2016, and experienced ≥1 episode of asymptomatic bacteriuria during the first 3 years posttransplantation.

Exposure

Recipient age, sex, diabetes, donor type, retransplant, urological abnormalities, thymoglobulin for induction, time since transplant, presence of ureteral stent, prior acute rejection, leukocyturia, hematuria, urinary nitrites, bacterial strain, prior urinary tract infection, resistance to antibiotics, antibiotic treatment.

Outcomes

The primary outcome was the occurrence of symptomatic urinary tract infection. The secondary outcome was antibiotic treatment of asymptomatic bacteriuria.

Analytical Approach

A Cox regression survival analysis model accounting for recurrent events and a logistic regression model.

Results

From a cohort of 508 patients, we included 597 episodes of asymptomatic bacteriuria detected in 119 outpatients. Antibiotics were prescribed in 26% of these episodes. Overall, 56 (9%) of episodes were followed by a symptomatic urinary tract infection. Pretransplant diabetes (hazard ratio [HR], 4.28; 95% confidence intervals [CI], 2.40-7.61), leukocyturia or hematuria (HR, 2.24; 95% CI, 1.27-3.96), and the presence of a ureteral stent (HR, 3.40; 95% CI, 1.33-8.70) were associated with development of a clinical urinary tract infection in patients with asymptomatic bacteriuria.

Limitations

The small number of events limits complete multivariable adjustment. It also prevents us from drawing a definite conclusion about the importance of a number of independent variables as risk factors for the outcome.

Conclusions

The benefit of treating episodes of asymptomatic bacteriuria with high-risk characteristics should be investigated in future trials.

Plain Language Summary

Urine infections are very frequent in patients who have received a kidney transplant. Bacteria are sometimes found in the urine of patients who report no symptoms. This is called asymptomatic bacteriuria. Asymptomatic bacteriuria is a risk factor for having an overt symptomatic urine infection, but previous small studies did not show any benefit of treatment. However, this may be different if only patients with asymptomatic bacteriuria at high risk of developing an overt infection were treated. In this study, we identified 3 features that put patients with asymptomatic bacteriuria at higher risk of developing overt infections: diabetes, presence of a stent in the ureter, and white or red blood cells in the urine when bacteriuria is detected. Examining the benefit of screening and treatment of asymptomatic bacteriuria in patients with these high-risk features warrants further investigation.