Urinary Tract Infection due to Corynebacterium urealyticum in Kidney Transplant Recipients: An Underdiagnosed Etiology for Obstructive Uropathy and Graft Dysfunction—Results of a Prospective Cohort Study
1Infectious Diseases Unit, and Departments of 2Microbiology and 3Nephrology, University Hospital 12 de Octubre, Madrid, Spain
Background.
Corynebacterium urealyticum is a cause of urinary tract infection and encrusting cystitis or pyelitis. Information about this infection in renal transplant recipients is based on case reports. We communicate the first prospective epidemiological study for this population.
Methods.We selected a cohort of 163 renal transplant recipients who were screened for urinary tract infection due to C. urealyticum. Long‐term incubation and special media were used for culture of C. urealyticum. The cohort was observed for a mean of 26.2 months (standard deviation, 8.7; range, 1–36 months). Risk factors and outcomes were assessed.
Results.At baseline, 16 (9.8%) of 163 patients had C. urealyticum bacteriuria (6 were asymptomatic, 9 had acute cystitis, and 1 had encrusting pyelitis). Independent risk factors (assessed by multivariate analysis) for urinary tract C. urealyticum infection were: antibiotic administration during the previous month (odds ratio, 8.04; 95% confidence interval, 1.57–41.06; 
), history of nephrostomy (odds ratio, 51.59; 95% confidence interval, 3.62–736.06; 
), and skin colonization (odds ratio, 208.35; 95% confidence interval, 21.54–2015.22; 
). Presence of urinary tract infection symptoms for >1 month (odds ratio, 27.7; 95% confidence interval, 2.55–300.5; 
) and obstructive uropathy (odds ratio 25.9; 95% confidence interval, 4.43–152.31; 
) were more frequent during follow‐up in patients with C. urealyticum bacteriuria.
Conclusions.When specifically tested for, C. urealyticum bacteriuria is more prevalent than previously thought in renal transplant recipients, and it is closely related to obstructive uropathy. Future studies are necessary to establish the relevance of treating the infection during follow‐up after renal transplantation.
Received 13 August 2007; accepted 7 November 2007; electronically published 8 February 2008.