Raoultella
Raoultella is a genus of Gram-negative, non-motile, facultatively anaerobic bacteria belonging to the family Enterobacteriaceae. These bacteria are commonly found in aquatic environments, soil, and also as opportunistic pathogens in clinical settings.
Classification and Taxonomy
Raoultella was initially classified within the Klebsiella genus. However, based on phylogenetic analyses and distinct biochemical characteristics, it was reclassified as a separate genus. Notable species within the Raoultella genus include Raoultella ornithinolytica, Raoultella terrigena, Raoultella planticola, and Raoultella electrica.
Characteristics
- Gram-negative rods
- Non-motile
- Facultatively anaerobic (can grow with or without oxygen)
- Oxidase-negative
- Catalase-positive
- Ferment lactose
- Produce gas from glucose fermentation
- Generally possess mucoid colonies due to capsule production
Clinical Significance
While often found in the environment, Raoultella species can act as opportunistic pathogens, particularly in immunocompromised individuals. They have been implicated in various infections, including:
- Pneumonia
- Bacteremia (bloodstream infections)
- Urinary tract infections (UTIs)
- Wound infections
Raoultella species can exhibit antibiotic resistance, including resistance to carbapenems and other beta-lactam antibiotics, posing a challenge for treatment. Identification of Raoultella is crucial for appropriate antibiotic selection and infection control measures.
Identification
Traditional biochemical tests can be used for initial identification, but molecular methods, such as 16S rRNA gene sequencing and MALDI-TOF mass spectrometry, provide more accurate and rapid identification of Raoultella species.