Low virulence? Clinical characteristics of Raoultella planticola bacteremia

Numerous case reports regarding Raoultella planticola infection have accumulated in the literature; however, its significance as a clinical pathogen remains unknown. We performed a retrospective review of R. planticola bacteremia to characterize its clinical features, antimicrobial susceptibility, and patient outcome.

Raoultella planticola bacteremia cases were culled from an electronic database of all bacteremia cases occurring over a 4-year-period. Medical records were retrospectively reviewed and demographic data, clinical findings, presence of underlying disease, results of antimicrobial susceptibility testing, and the antibiotic regimens administered during the treatment were evaluated.

Raoultella planticola was isolated from blood culture specimens in 20 cases. The majority of these patients had underlying malignant conditions (17 patients, 85%). The most prevalent causes of malignancy were adenocarcinoma involving the gallbladder or bile duct (7 patients) and hematologic malignancies (6 patients). No cases with resistance to carbapenem or third generation cephalosporins were found. All 14 patients with R. planticola as the sole microbial isolate recovered with the use of empirical antibiotics. Of the six patients with polymicrobial infection, three did not recover and subsequently expired.

Raoultella planticola bacteremia seemed to occur mainly in immunocompromised patients, and was also frequently found in patients with lesions involving the gallbladder or bile duct. The overall outcome was favorable when R. planticola was treated with administration of empirical antibiotics. Mixed outcomes were found when blood cultures yielded multiple species of microbes.