bacterial variants that do not have rigid cell walls but that may contain varying amounts of cell wall material; they are spheric to coccobacillary in shape and vary in size from small bodies that pass through filters, which retain bacteria to bodies that are larger than the bacterial form; they are gram-negative and resistant to penicillin. The variants differ greatly from the parent bacterial cells in mode of reproduction, physiology, growth requirements, and individual and colonial morphology; they are generally considered to be nonpathogenic, even if derived from a pathogenic bacterium. [L. fr. Lister Institute]
