Background: The role of asymptomatic bacteriuria in kidney transplant recipients is unknown. There is no clear evidence of its effect on transplanted kidney.
Methods: We studied urine cytokines profile among kidney transplant recipients with bacteriuria found in screening examination. Urine cultures were collected in 269 patients with stable graft function and serum creatinine level <2 mg/dl, during their routine visits. Interleukin (IL)-6 and IL-8 levels were measured in urine samples from patients with asymptomatic bacteriuria, symptomatic urinary tract infection and patients without bacteriuria (control group). Changes in serum creatinine level in patients with asymptomatic bacteriuria and in the control group were observed during 12 months follow up.
Results: Urinary tract infection (UTI) was diagnosed in five patients and asymptomatic bacteriuria in 22 patients. Urine IL-6 level was significantly higher in symptomatic UTI group (median 15.71 pg/mg) but there were no differences between group of patients with asymptomatic bacteriuria (3.92 pg/mg) and control group (2.54 pg/mg). Urine IL-8 level was higher in symptomatic UTI group (median 146.8 pg/mg) and was also significantly higher in asymptomatic bacteriuria group (33.49 pg/mg) in comparison to control group (2.97 pg/mg; P=0.0002). During 1-year follow up, incidence of UTI was higher in the asymptomatic bacteriuria group than in the control group but graft function was not different in both groups.
Conclusions: Elevated urine IL-8 level in kidney transplant patients with asymptomatic bacteriuria may reflect impaired immune response to bacterial infection and occult inflammatory process in urinary tract.