Classification refers to the orderly arrangement of the bacteria into groups.
The word, "mycoplasmas" is sometimes a general term to represent the smallest self-replicating organisms with the smallest genomes. The mycoplasmas are classified as Mollicutes. In Latin, this word translates to "soft skin".
At present, Mollicutes are the smallest free-living organisms.
The domain, bacteria, contains the class Mollicutes:
- Which contains the order Mycoplasmatales,
- Which contains the family Mycoplasmataceae (this is the family that has been identified to colonize or infect humans),
- Which contains the medically important genera, Mycoplasma and Ureaplasma. (The complete genera contain over 100 different species.)
While mycoplasmas may be found everywhere in nature, this course will focus on the cell wall-deficient, medically important bacteria, Mycoplasma and Ureaplasma. The following genera and species will be highlighted:
- Mycoplasma pneumoniae
- Mycoplasma genitalium
- Mycoplasma hominis
- Ureaplasma parvum
- Ureaplasma urealyticum
Note: While other related genera and species have been isolated from humans on occasion (ie, Acholeplasma laidlawii, Mycoplasma pirum, Mycoplasma amphoriforme, Mycoplasma fermentans, Mycoplasma penetrans) their significance is somewhat uncertain - and tied most often with immune status, such as in patients infected with human immunodeficiency virus (HIV).4 These bacteria will not be discussed further in this forum.
4. Tille PM. Bailey & Scott's Diagnostic Microbiology. 15th ed. Elsevier. 2022.
