They now are the most common post-transplant uropathogen.
TORONTO—Enterococcus has emerged as the predominant pathogen associated with symptomatic UTIs in the first six months after renal transplantation, data show.
George Alangaden, MD, associate professor of medicine at Wayne State University School of Medicine in Detroit, and his colleagues reviewed the records of the 207 patients (43% women) at their institution who underwent a renal transplant between July 1, 2001 and December 31, 2005 and developed symptomatic UTIs (those with asymptomatic bacteriuria were excluded). All patients received perioperative cefazolin and pneumocystis prophylaxis with trimethoprim/ sulfamethoxazole (TMP/SMX) for six months.
Symptomatic UTIs occurred in 47 patients (23%), of which 31 (66%) were female, the researchers reported here at the Infectious Diseases Society of American annual meeting. Among the 95 episodes of symptomatic UTI, 72 occurred in females; women also accounted for 18 of 21 of patients with more than one UTI.
Of the 95 symptomatic UTIs, 18% occurred within four weeks, 17% between one and six months, and 65% occurred six months or more after transplantation. Overall, the most common uropathogens were E. coli (39%), Enterococcus sp. (20%), Klebsiella sp. (9%), Enterobacter sp. (7%), Pseudomonas aeruginosa (6%), and Candida sp. (6%). Among six isolates from candidal UTIs, four were Candida glabrata.
Dr. Alangaden said it was notable that within the first six months after renal transplantation, Enterococcus accounted for 27% of UTIs, and 70% of those occurred within four weeks post-transplant compared with just 15% of UTIs in the first six months due to E. coli. Conversely, after six months, 52% of the UTIs were caused by E. coli compared with 16% caused by Enterococcus. The investigators observed vancomycin resistance in 26% of the Enterococcus isolates. Among the 37 E. coli isolates, 27% were resistant to TMP/SMX, 41% were resistant to ampicillin, 11% were resistant to ciprofloxacin, and 11% were resistant to an aminoglycoside.
“It is well known that UTIs occur predominantly in women,” Dr. Alangaden said. “In our study, recurrent UTIs occurred most often in female recipients who experienced an episode of rejection. Although Enterococcus is one of the uropathogens isolated from UTIs among renal transplant recipients, we were surprised that it has replaced E. coli as the commonest uropathogen within the first six months following renal transplantation.”
The reasons for this emerging trend are unclear, but Dr. Alangaden observed: “It is likely the emergence of Enterococcus may be due to multiple risk factors, including the fact that soon after transplant these patients are within the hospital environment with indwelling vascular catheters, urinary stents, urinary catheters, and exposure to antibiotics.”
Clinicians may need to consider appropriate empiric antimicrobial coverage to include Enterococcus and antibiotic-resistant E. coli when treating symptomatic UTIs in renal transplant recipients.
“The most important measure to avoid the emergence of these resistant uropathogens would be prudent antibiotic usage. Furthermore, additional studies are needed to provide guidance for appropriate antibiotic use in the management of asymptomatic bacteriuria in renal transplant recipients, and that is something that we are in the process of evaluating in a prospective manner,” Dr. Alangaden said.