Mycoplasmas are the smallest bacteria capable of self-replication. They lack cell walls and are bounded only by a plasma membrane, making them pleomorphic in shape. Many species are pathogens of plants, animals, and humans, causing diseases like atypical pneumonia in humans from M. pneumoniae, bovine pleuropneumonia from M. mycoides, and chronic respiratory disease in chickens from M. gallisepticum. Mycoplasmas have complex growth requirements and can be difficult to culture, but are widespread in nature.

1. Mycoplasmas
(pleuropneumonia like
organisms”(PPLO)
In 1898, Nocard and Roux were the first to isolate a
mycoplasma species in culture from bovine.

2. Mollicutes (The Mycoplamas)
• The class Mollicutes has five orders and six families. The best studied genera
are found in the orders
• Mycoplasmatales (Mycoplasma, Ureaplasma)
• Entomoplasmatales (Entomoplasma, Mesoplasma, Spiroplasma)
• Acholeplasmatales (Acholeplasma)
• Anaeroplasmatales (Anaeroplasma, Asteroleplasma)
• Haloplasmatales (Haloplasma)
• Although they evolved from ancestors with gram positive cell walls, they now
lack cell walls and cannot synthesize peptidoglycan precursors.
• Many can pass through a bacterial filter
• Thus they are penicillin resistant but susceptible to lysis by osmotic shock and
detergent treatment.

3. (lipoprotein)

4. • Because they are bounded only by a plasma membrane, these prokaryotes are
pleomorphic and vary in shape from spherical or pear-shaped organisms, about
0.3 to 0.8 min diameter, to branched or helical filaments
• They are among the smallest bacteria capable of self-reproduction
• Although most are non-motile, some can glide along liquid-covered surfaces
• Most are facultative anaerobes, but a few are obligate anaerobes.
• When growing on agar, most species form colonies with a “fried-egg”
appearance because they grow into the agar surface at the center while
spreading outward on the surface at the colony edges

5. • Saprophytes, commensals, or parasites, and many are pathogens of plants,
animals, or insects
• Incapable of synthesizing a number of macromolecules
• In addition to requiring sterols, they also need fatty acids, vitamins, amino
acids, purines, and pyrimidines
• Widespread and can be isolated from animals, plants, the soil, sewage and
even compost piles.
• Although their complex growth requirements can make their growth in pure
cultures difficult, about 10% of the mammalian cell cultures in use are probably
contaminated with mycoplasmas.
• In animals, mycoplasmas colonize mucous membranes and joints and often are
associated with diseases of the respiratory and urogenital tracts
Eaton's agar

6. • Mycoplasmas cause several major diseases in livestock, for example,
contagious bovine pleuropneumonia in cattle (M. mycoides),
• chronic respiratory disease in chickens (M. gallisepticum),
• and pneumonia in swine (M. hyopneumoniae).
• M. pneumonia causes primary atypical pneumonia in humans .

7. Diseases Caused by Mycoplasma
• Organism Disease
• M. pneumoniae Upper respiratory tract disease, tracheobronchitis, atypical pneumonia,
(chronic asthma)
• M. hominis Pyelonephritis, pelvic inflammatory disease, postpartum fever
• M. genitalium Nongonococcal urethritis
• M. mycoides bovine pleuropneumonia in cattle
M. gallisepticum chronic respiratory disease in chickens
M. hyopneumoniae pneumonia in swine