Mycoplasma refers to a genus of bacteria that lack a cell wall and possess a three-layered cellular membrane. They can be parasitic or saprotrophic. Several species are sexually transmitted and pathogenic in humans. Others are found on cats, dogs, and barnyard fowl.
It includes the species:
In 1967, the order Mycoplasmatales was incorporated into the class Mollicutes. Many species are sexually transmitted and cause pelvic inflammatory disease.