SYNOPSIS OFCOMMONFOODBORNEBACTERIA
These synopses are provided to give the reader glimpses of bacterial groups that are discussed throughout the textbook. They are not meant to be used for culture identifications. For the latter, one or more of the cited references should be consulted. Some of the phylogenetic features of these bacteria are presented in the Appendix
Acinetobacter (A • ci • ne’to • bac • ter; Gr. akinetos, unable to move). These Gram-negative rods show some affinity to the family Neisseriaceae, and some that were formerly achromobacters and moraxellae are placed here. Also, some former acinetobacters are now in the genus Psychrobacter. They differ from the latter and the moraxellae in being oxidase negative. They are strict aerobes that do not reduce nitrates. Although rod-shaped cells are formed in young cultures, old cultures contain many coccoid-shaped cells. They are widely distributed in soil and water and may be found on many foods, especially refrigerated fresh products.
Aeromonas(ae•ro•mo’nas;gasproducing).ThesearetypicallyaquaticGram-negativerodsformerly in the family Vibrionaceae but now in the family Aeromonadaceae.32 As the generic name suggests, they produce copious quantities of gas from the fermented sugars. They are normal inhabitants of the intestines of fish, and some are fish pathogens.
Alcaligenes (al • ca • li’ge • nes; alkali producers). Although Gram negative, these organisms sometimes stain Gram positive. They are rods that do not, as the generic name suggests, ferment sugars but instead produce alkaline reactions, especially in litmus milk. Nonpigmented, they are widely distributed in nature in decomposing matter of all types. Raw milk, poultry products, and fecal matter are common sources.
Alteromonas(al•te•ro•mo’nas;anothermonad).Thesearemarineandcoastalwaterinhabitantsthat are found in and on seafoods; all species require seawater salinity for growth. They are Gram-negative motile rods that are strict aerobe.
Arcobacter (Ar’co • bac • ter; L. arcus, bow). This genus was created during revision of the genera Campylobacter, Helicobacter, and Wolinella,45 and the three species were once classified as Campylobacter. They are Gram-negative curved or S-shaped rods that are quite similar to the campylobacters except they can grow at 15◦C and are aerotolerant. They are found in poultry, raw milk, shellfish, and water; and in cattle and swine products