''Plesiomonas shigelloides'' is a species of bacteria and the only member of its genus. It is a

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

, rod-shaped bacterium which has been isolated from freshwater, freshwater fish, shellfish, cattle, goats, swine, cats, dogs, monkeys, vultures, snakes, toads and humans. It is considered a fecal coliform. ''P. shigelloides'' is a global distributed species, found globally outside of the polar ice caps. ''P. shigelloides'' has been associated with the diarrheal disease state in humans, but has been identified in healthy humans as well. It can enter the body either through contact with water contaminated by fecal matter or through seafood originating from a contaminated source.

Classification

''P. shigelloides'' was originally considered part of the family ''Vibrionaceae'', but is generally accepted to be part of ''Enterobacteriaceae'' due to the similarity of its 5S rRNA sequence to other members of ''Enterobacteriaceae'.'' The rRNA sequence of ''P. shigelloides'' has been found to be most similar to '' Proteus mirabilis,'' and as a result it is now considered part of the tribe ''Proteeae'' within the family ''Enterobacteriaceae''. ''P. shigelloides'' is the only known member of its genus.

Ecology

Growth

''P. shigelloides'' is incapable of surviving in saltwater environments where the concentration of salt is greater than 4% and has been found to tolerate pH ranges between 4.5 and 9. It grows optimally between 35 °C and 39 °C, and has been found to survive in the temperature range of 8 °C to 45 °C. The effects of pH, salinity, temperature, turbidity, and conductivity on concentrations of ''P. shigelloides'' in freshwater conditions is not currently understood.

Identification

Some ''Plesiomonas'' strains share antigens with '' Shigella sonnei'' and '' Shigella flexneri'' and cross-reactions with ''Shigella'' antisera may occur. ''Plesiomonas'' can be distinguished from ''Shigella'' in diarrheal stools by an oxidase test: ''Plesiomonas'' is oxidase positive and ''Shigella'' is oxidase negative. ''Plesiomonas'' is easily differentiated from ''Aeromonas sp.'' and other oxidase-positive organisms by standard biochemical tests.

Pathogenicity

Human infection

''P. shigelloides'' has been isolated from a wide variety of human clinical specimens including both intestinal (usually feces or rectal swabs) and extra-intestinal. It has been isolated from the feces of humans, both with and without diarrhea, and/or vomiting (

gastroenteritis Gastroenteritis, also known as infectious diarrhea, is an inflammation of the Human gastrointestinal tract, gastrointestinal tract including the stomach and intestine. Symptoms may include diarrhea, vomiting, and abdominal pain. Fever, lack of ...

). Although reports have found a link between ''P. shigelloides'' and diarrhea or

, research has not yet determined whether this bacteria is always responsible for these conditions.

Infection of other animals

Although ''P. shigelloides'' is primarily associated with the diarrheal disease state in humans, certain animals including cats and dogs have been found to frequently carry the bacterium while in a healthy state. Freshwater fish can often be infected with ''P. shigelloides'' which can be lethal depending on the concentration of the bacterium in their bodies.

References

External links

Type strain of ''Plesiomonas shigelloides'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q3768142 Pathogenic bacteria Bacteria described in 1954