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Related to Mycoplasmas: Mycoplasma genitalium


The smallest prokaryotic microorganisms that are able to grow on cell-free artificial media. Their genome size is also among the smallest recorded in prokaryotes, about 5 × 108 to 109 daltons. The mycoplasmas differ from almost all other prokaryotes in lacking a rigid cell wall and in their incapability to synthesize peptidoglycan, an essential component of the bacterial cell wall.

Taxonomically, the mycoplasmas are assigned to a distinct class, the Mollicutes, containing two orders, Mycoplasmatales and Acholeplasmatales. The distinction between the orders is based primarily on differences in nutritional criteria: members of the Mycoplasmatales require cholesterol or other sterols for growth whereas those of the second order do not. The term mycoplasmas is generally used as the vernacular or trivial name for all members of the class Mollicutes, irrespective of the classification in a particular genus.

The mycoplasmas are almost ubiquitous in nature. Several species are important pathogens of humans, animals and plants, while others constitute part of the normal microbial flora of, for example, the upper respiratory and lower urogenital tracts of humans. Mycoplasma pneumoniae was found to be the cause of cold agglutinin-associated primary atypical pneumonia. This disease is particularly frequent in the 5–15-year age group; it is probably endemic almost all over the world and often reaches epidemic proportions at intervals of 4 to 5 years.

Mycoplasmas are generally highly resistant to benzyl penicillin and other antibiotics which act by interfering with the biosynthesis of peptidoglycan. They are usually susceptible to antibiotics that specifically inhibit protein synthesis in prokaryotes, such as tetracyclines and chloramphenicol. Susceptibility to other antibiotics, such as erythromycin and other macrolides, is variable. See Antibiotic, Bacterial physiology and metabolism, Plant pathology, Pneumonia

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The 16S rDNA PCR amplicon from the 16 positive samples was obtained, showing that they had the same length as Mycoplasma sp.
ovipneumoniae and illustrates the divergence from the other Mycoplasma spp.
PCR based detection of Mycoplasma bovis from bovine clinical specimens.
Mycoplasma gallisepticum (MG), causative agent of chronic respiratory diseases (CRD), is one of the most economically significant mycoplasma pathogens of poultry that has been reported from all over the world including Pakistan (Kleven and Levisohn, 1996).
This is the first known case of Mycoplasma hominis primary peritonitis in an otherwise healthy female.
The gene alr encodes for alanine racemase and is involved in the peptidoglycan synthesis, yet the function of this enzyme in Mycoplasma species is not clear.
Detection and identification of avian mycoplasmas by polymerase chain reaction and restriction fragment length polymorphism assay.
Isolation of Mycoplasma genitalium from first-void urine specimens by coculture with Vero cells.