Clinical characteristics of Raoultella ornithinolytica bacteremia.

PURPOSE: Raoultella ornithinolytica is not well known as a clinical pathogen. We performed a retrospective review of R. ornithinolytica bacteremia to investigate its clinical features, antimicrobial susceptibility, and overall patient outcomes.

METHODS: R. ornithinolytica bacteremia cases were collected from an electronic database of all cases of bacteremia over a 10-year period. Medical records were retrospectively reviewed. Demographic data, clinical information, the presence of underlying comorbidities, the results of antimicrobial susceptibility testing, and the antimicrobial regimen administered were investigated.

RESULTS: R. ornithinolytica was isolated from blood culture specimens in 16 cases. The majority of these patients had an underlying malignant condition of advanced stage (15 patients, 94 %). Seven of these patients had a solid tumor with lesions or metastases that extended to the bile duct or biliary tract. Neutropenic fever following hematologic stem cell transplantation was found in three cases. No resistance to piperacillin/tazobactam or imipenem was found. Four cases showed resistance to cefoxitin, while one of these cases showed resistance to multiple cephalosporins. In overall outcomes, seven patients (44 %) did not recover from the infection and subsequently expired.

CONCLUSIONS: R. ornithinolytica bacteremia occurs mainly in patients with underlying malignancies. The overall outcome was not favorable, despite favorable antimicrobial susceptibility test results. The findings of this study contradict those of other studies that demonstrated that infection from Raoultella species have good prognoses.