BOSTON—Older age, female gender, and delayed graft function are among the independent risk factors for recurrent urinary tract infections (UTIs) among renal transplant recipients, according to a new prospective study presented at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy. The risk for future UTIs also is increased if the first UTI is caused by a multidrug-resistant pathogen.

The risk for recurrent UTIs increased by 2% for each year of age, researchers reported. Female patients had a 1.8 times increased risk compared with male patients. Delayed graft function, hepatitis C virus infection, and polycystic kidney disease as a cause of transplantation each was independently associated with a twofold-increased risk of recurrent UTIs. If the first UTI was caused by a multidrug-resistant pathogen, the risk was increased 5.6 fold.

“These findings are important because they point to ways of reducing the rates of recurrent urinary tract infections in renal transplant patients,” said lead investigator Carlos Cervera, MD, Associate Professor of Medicine in the Division of Infectious Diseases at the University of Barcelona in Spain. “You have take steps to lower risks. That may mean removing the urinary catheter as soon as possible and trying to reduce antibiotic use as much as possible.”

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Another preventive strategy may be to discharge renal transplant patients from the hospital as soon as possible, Dr. Cervera said.

UTIs are the most common infectious complication in renal transplant recipients, he said, adding that most UTIs occur within 12 months of transplantation. Renal transplant recipients have higher rates of UTIs, hospitalizations, and deaths due to gram-negative septicemia associated with pyelonephritis compared to patients on renal transplant waiting lists.

Dr. Cervera and his colleagues studied 473 renal transplant recipients (272 male) with a mean age of 51 years. Patients who experienced two or more UTI episodes were considered to have recurrent UTIs. Multidrug-resistant organisms were those that were resistant to three or more types of antibiotics or produced extended-spectrum beta-lactamases.

All patients received cefazolin immediately prior to surgery and trimethoprim/sulfamethoxazole (TMP/SMX) three times during the first six months post-transplantation for Pneumocystis jirovecii pneumonia prophylaxis. Patients with proven allergy to sulfamides received inhaled pentamidine. The mean follow-up for the study was 625 days.

The investigators identified 291 UTI episodes in 151 patients, which translated into a cumulative incidence of 32% and an incidence rate of 9.06 episodes per 10,000 transplant days.  Among these 151 patients, 37 (13%) had positive blood cultures. Recurrent UTIs occurred in 65 patients (14%). Escherichia coli were responsible for 43% of the episodes, followed by Klebsiella species (17%), Pseudomonas aeruginosa (14%), and enterococci (12%). Multidrug-resistant isolates represented 33% of the strains, and 44 patients (9%) were diagnosed as having their first UTI with a multidrug resistant pathogen.