A microbiology technologist is reading an anaerobic plate from an intestinal abscess.There is growth on the Bacteroides bile esculin (BBE) plate: gray colonies with a brown color in the area around the colonies.There is also a dark precipitate in the medium in the areas of heavy growth.The microbiologist Gram stains the colonies and observes gram-negative coccobacilli.What is the presumptive identification of this organism?

Question

Quizplus · Accepted Answer

Colonies of the B.fragilis group on the BBE agar plate are gray and a minimum of 1 mm in diameter.The originally light-yellow medium turns brown in the area around the colonies.A dark precipitate in the medium around the areas of heavy growth is suggestive of the species B.fragilis, although some strains of B.ovatus also cause stippling.

A Microbiology Technologist Is Reading an Anaerobic Plate from an Intestinal