27 Jun 2022

Serratia species

An aerobic gram-negative bacillus that grows readily on most microbiological media producing either a white, pink (pyrimine) or red (prodigiosin) colony. Pigment production occurs between 12oC and 36oC. Unlike prodigiosin, pyrimine is water soluble and is capable of diffusing into the medium, turning it pink. Species are capable of growth between 4oC and 40oC but some of the important pathogens are incapable of growth above 35oC. They may produce either a fishy-urinary odor (trimethylalamine) or a musty-potato-like odor (2-methoxy-3-isopropyl-pyrazine). They can be isolated from food, soil, water, plants, insects, and sewage. Some species are potential pathogens for insects, animals, and humans and are an important cause of nosocomial (hospital-acquired) infections in humans.