Enterobacter

Enterobacter is a genus of Gram-negative, facultatively anaerobic, rod-shaped bacteria in the family Enterobacteriaceae. Members are typically motile with peritrichous flagella and may be encapsulated. They are lactose fermenters and occur in a variety of environments, including soil, water, plants, and the gastrointestinal tracts of humans and animals. The genus includes several medically relevant species, most notably those within the Enterobacter cloacae complex. Taxonomic revisions have moved some species historically placed in Enterobacter to other genera; for example, Enterobacter aerogenes has been reclassified as Klebsiella aerogenes in some taxonomic systems.

Enterobacter spp. are opportunistic pathogens commonly implicated in healthcare-associated infections such as urinary tract infections, pneumonia, bacteremia, wound infections, and intra-abdominal infections. They readily form biofilms on indwelling devices such as catheters and ventilators, which can complicate treatment. They are generally susceptible to a range of antibiotics, but many strains produce AmpC beta-lactamases and can harbor extended-spectrum beta-lactamases (ESBLs) and, less often, carbapenemases, contributing to multidrug resistance.

For laboratory identification, Enterobacter are Gram-negative, facultatively anaerobic rods that ferment lactose. On culture, they typically grow as smooth, moist colonies on blood and MacConkey agar, producing pink colonies on MacConkey due to lactose fermentation. They are oxidase-negative and catalase-positive, and antibiotic susceptibility testing guides therapy.