A rare cause of infection, Raoultella planticola: emerging threat and new reservoir for carbapenem resistance

Background Severe cases of infections caused by Raoultella planticola are constantly being reported from all over the world with the increase in drug-resistance patterns. In this study, we retrospectively evaluated the clinical characteristics of R. planticola infections with patients' demographics and antimicrobial susceptibilities of the R. planticola isolates. Methods R. planticola isolates were retrospectively evaluated. VITEK 2 (R) automated system was used for identification and antimicrobial susceptibility testing. Verification of the low-discriminated isolates was analyzed with MALDI-TOF method using VITEK MS (R) system. Gene-Xpert (R) system was used for detection of bla(IMP-1)-, bla(KPC)-; bla(NDM-1)-, bla(OXA-48)- and bla(VIM)-type carbapenemases. The data of the patients with R. planticola infection were collected from hospital records. Result During the 4-year period, 42 episodes of R. planticola infections were detected. MALDI-TOF was used for 11 of the low-discriminated isolates, and 1 of which identified as R. terrigena was excluded. Carbapenems and aminoglycosides were the most effective antimicrobial agents. Extended spectrum beta-lactamases were detected in seven of the isolates. Three carbapenem-resistant isolates were detected as bla(OXA-48)-type carbapenemase carrier. Nosocomial R. planticola infections constituted 80.9 % (n = 34) of the infections. Most common infections related with R. planticola were blood stream infections (n = 24) (p < 0.005). The presence of indwelling catheter and intensive care unit stay were the most common detected risk factors (p < 0.005). Diabetes mellitus and chronic renal insufficiency commonly accompanied the infections (p > 0.005). Conclusions Challenging infections caused by Raoultella spp., like those of multidrug resistant Klebsiella spp., will probably become a concern for clinicians as well as microbiologists. In literature, there were few cases, but we believe that the incidence of Raoultella spp. infections, which may result from misidentification, are more common than expected, and it is not unlikely that there will be a gradual increase and spread in multidrug-resistant isolates.