Combination of Tigecycline and Levofloxacin for Successful Treatment of Nosocomial Pneumonia Caused by New Delhi Metallo-β-Lactamase-1-ProducingRaoultella planticola

Raoultella planticola is a gram-negative bacterium that rarely causes diseases in humans. Here, we present a case of hospital-acquired pneumonia caused by R. planticola that likely originated in the gastrointestinal tract. To the best of our knowledge, this is the second report describing the detection of the gene New Delhi Metallo-β-lactamase-1 (blaNDM-1) in multidrug-resistant R. planticola. Clinical samples were collected for bacterial culture and antimicrobial susceptibility testing from a patient during hospitalization. The presence of blaNDM-1 was detected by PCR and sequencing. An NDM-1-positive R. planticola was isolated from the sputum and stool of the same patient. Further findings confirmed that blaNDM-1 was located on a plasmid. Isolates from the sputum and stool cultures were identical, suggesting that the R. planticola may have originated in the gastrointestinal tract. The patient completely recovered and was discharged after treatment with tigecycline combined with levofloxacin, for a week. In conclusion, R. planticola is a possibly underestimated pathogen that contributes to the spread of the blaNDM-1 gene. Early and precise identification of this pathogen can lead to better prognosis of the associated infections and an improved approach to controlling the spread of carbapenemase-resistant gram-negative bacteria.