Rahnella aquatilis Bacteremia in an Oncologic Patient with Intestinal Obstruction. Identification of Unusual Bacteria is not Always Easy. Literature Review

Rahnella aquatilis is a gram-negative rod that belongs to the Enterobacteriaceae family. Few cases of infections by this bacteria have been reported in humans. Most of them are opportunistic infections in immunocompromised patients, but some cases have also been described among immunocompetent subjects. In this article, we present a case of bacteremia originated by this microorganism in a patient with advanced stage breast cancer. The patient was receiving palliative treatment, and presented a long-term intestinal obstruction. Initial identification of this bacterium was uncertain with biochemical methods, and the strain was identified as Rahnella aquatilis by MALDI-TOF mass spectrometry (MS). The identification of Rahnella was definitely confirmed by 16S sequencing. In addition, a review of cases of infection by R. aquatilis has been made in the literature. We tried to show the patients and what types of infections are caused by Rahnella.