Pantoea bacteria belong to a large group of organisms of the Enterobacteriaceae family, also called enteric bacilli. All members of Enterobacteriaceae are Gram-negative bacilli or coccobacilli ranging from 0.3 µm to 1.0 µm wide by 0.6 µm to 6.0 µm long. When Gram-stained, all Enterobacteriaceae look alike. Enterobacteriaceae species do not form spores and grow best without oxygen, although they are able to grow with oxygen present in their environment.
Enterobacteriaceae bacteria are found in water, soil, and GI tract of humans and animals. The prefix entero- refers to the gastrointestinal (GI) tract. Thus, the name Enterobacteriaceae implies that members of this family are bacteria having association with the GI tract.
Enterobacteriaceae are associated with various human and animal diseases, including abscesses, GI tract infections, meningitis, septicemia, pneumonia, urinary tract infections, and wound infections. They are among the most common hospital-acquired infections. Most GI infections are caused by organisms in four groups (genera): Escherichia, Salmonella, Shigella, and Yersinia, although other members of the family have been implicated in diarrheal diseases.3 Most extraintestinal infections are caused by Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis, Pantoea agglomerans, Enterobacter aerogenes, and Enterobacter cloacae.
To date, the genus Pantoea consists of 22 species and 2 subspecies. Although members of the genus Pantoea are primarily plant pathogens, they occur in many ecological habitats, including in association with soil, water, dairy products, meat, fish, humans, and animals. Plant surfaces, seeds, human clinical specimens, animals, and raw and frozen vegetables harbor Pantoea agglomerans. In cotton, Pantoea agglomerans causes internal lint rot. No external boll damage is observed. Damage can be severe. Internal lint damage occurrs in bolls tips that formed abnormal fissures or openings nearest the sutures. The bolls may contain abnormal tip structure. Pantoea dispersa has been recovered from plant surfaces, seeds, and humans. Pantoea citrea, Pantoea punctata, and Pantoea terrea have been isolated from Japanese mandarin oranges. Pantoea terrea has also been isolated from soil. Pantoea ananas has been isolated from pineapples, and rice seeds. Pantoea stewartii has been isolated from grasses, pineapples and beetles.1, 3 It is also the causative agent of Stewart's wilt and leaf blight in corn. In nature it is largely dependent on its corn flea beetle vectors, predominantly Chaetocnema pulicaria. It is thought to persist in the alimentary tracts of adult flea beetles that overwinter in the soil, thus enabling its transmission to new plants in the spring.10
Some Pantoea species have been shown to be beneficial in association with plants. P. vagans is used as a biocontrol agent to protect against fire blight and P. agglomerans can protect against plant pathogens like Pseudomonas syringae.11
Most strains of Pantoea agglomerans, previously called Enterobacter agglomerans, feed on decaying organic material. Some strains have shown to be able to survive for 750 hours in seawater. This organism has been recovered from dead mahi-mahi (dolphin fish, Coryphaena hippurus) in which it causes bleeding in the eyes.2. In humans, Pantoea agglomerans has been recovered from wounds which have been acquired through cuts and thorn pricks. Cases of septic arthritis (inflammation of the joint) and osteomyelitis (inflammation of the bone) caused by Pantoea agglomerans have developed after plant thorn injuries and wood splinter injuries. Most serious infections have occurred in persons with diminished host defenses. Meningitis of the newborn has also been documented. Often, blood poisoning (bacteremia) with Pantoea agglomerans is accompanied by fever, shaking chills, and general toxicity. Eye and skin infections are particularly prominent.4, 5
Pantoea agglomerans produces the broad-spectrum antibiotic andrimid. This potent antibiotic kills a wide range of bacteria by blocking a critical step in fatty acid biosynthesis.7,8
The human pathogens include species such as P. septica and P. brenneri. Recently, Pantoea anthophila was isolated from hypersaline water from the lake on Laysan, Northwestern Hawaiian Islands.