Microbiology of genus Raoultella, clinical features and difficulties in its diagnosis

The genus Raoultella, which belongs to the Enterobacteriaceae family, encompasses gramnegative, oxidase-negative, aerobic, encapsulated and motionless bacilli. Currently, four species of this genus have been described: Raoultella terrigena (R. terrigena), Raoultella planticola (R. planticola), Raoultella ornithinolytica (R. ornithinolytica) and Raoultella electrica (R. electrica), out of which R. planticola and R. ornithinolytica are the most important because of their probable association as pathogenic agents. The incidence of this genus has been underestimated, given that detecting it is really difficult, since it is misidentified as Klebsiella spp. by using manual and automated conventional phenotypic methods. The rapid and correct detection has been increasing since the advent of mass spectrometers (MALDI-TOF MS), which have been used for the differentiation of Klebsiella spp. and Raoultella spp. Currently 80 cases of bacteremia secondary to Raoultella spp. have been identified with different sites of primary infection, which is why it is important to emphasize proper detection in hospitals and healthcare facilities.