Raoultella

Raoultella is a genus of Gram-negative, nonmotile, encapsulated rods in the Enterobacteriaceae family. The species within Raoultella were formerly classified as Klebsiella, and the genus was established in 2001 following phylogenetic analyses. The best-known species are Raoultella planticola, Raoultella ornithinolytica, and Raoultella terrigena. The genus is named in honor of French microbiologist Didier Raoult.

Habitat and ecology: Members of Raoultella are primarily environmental bacteria found in soil, water, and associations with plants. They can be isolated from food and clinical samples but are generally considered environmental or opportunistic.

Clinical relevance: Raoultella species can cause human infections, particularly in people with underlying conditions or compromised immunity. Reported clinical manifestations include bacteremia, pneumonia, urinary tract infections, wound infections, and intra-abdominal infections. In hospital settings, they are recognized as opportunistic pathogens. Most isolates remain susceptible to many antibiotics, but instances of antimicrobial resistance, including beta-lactamase production, have been reported; treatment should be guided by susceptibility testing.

Laboratory identification: In clinical laboratories, Raoultella may resemble Klebsiella and other Enterobacteriaceae. Accurate identification often requires molecular methods (such as 16S rRNA sequencing or rpoB) or matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).