A genus of gram-negative, facultatively anaerobic, rod-shaped bacteria that occurs in fish and other aquatic animals and in a variety of mammals, including man. Its organisms probably do not belong to the normal intestinal flora of man and can cause diarrhea.

A family of gram-negative bacteria whose members predominate in the bacterial flora of PLANKTON; FISHES; and SEAWATER. Some members are important pathogens for humans and animals.

A genus of gram-negative, facultatively anaerobic, rod-shaped bacteria that occurs singly, in pairs, or in short chains. Its organisms are found in fresh water and sewage and are pathogenic to humans, frogs, and fish.

Infections caused by bacteria that show up as pink (negative) when treated by the gram-staining method.

An increased liquidity or decreased consistency of FECES, such as running stool. Fecal consistency is related to the ratio of water-holding capacity of insoluble solids to total water, rather than the amount of water present. Diarrhea is not hyperdefecation or increased fecal weight.

A lactose-fermenting bacterium causing dysentery.