Mycoplasma are a bacterial species that are a common cause of community-acquired pneumonia and sexually transmitted infections (eg, nongonococcal urethritis).
Mycoplasmas are ubiquitous bacteria that differ from other prokaryotes in that they lack a cell wall. As a result, they are difficult to visualize with Gram stain, and antibiotic therapies that target cell-wall biosynthesis (eg, penicillins, cephalosporins) are ineffective.
Fourteen species of Mycoplasma have been isolated from humans, and 4 of them are well-established causes of human disease:
Mycoplasma hominis
Mycoplasma pneumoniae
Mycoplasma genitalium
Ureaplasma urealyticum
Mycoplasmas are not visible with light microscopy.
For diagnosis, screening, and treatment recommendations for Mycoplasma species, see Chlamydia and Mycoplasmal Mucosal Infections.
Mycoplasma pneumoniae
M. pneumoniae is a common cause of respiratory infections, including acute upper respiratory infection (URI) and acute bronchitis. It can cause pneumonia in a subset of patients, particularly community-acquired pneumonia. Because mycoplasma infections do not respond to beta-lactam antibiotics as do most cases of community-acquired pneumonia, they are sometimes described as atypical pathogens.
Outbreaks of mycoplasma pneumonia have occurred in congregate settings, including schools, children's summer camps, and military facilities.
M. pneumoniae can also be a cause of reactive airway disease.
Mycoplasma genitalium
Evidence suggests that M. genitalium and U. urealyticum cause some cases of sexually transmitted infections, including nongonococcal urethritis. They (and M. hominis) are often present in patients with other urogenital infections (eg, vaginitis, cervicitis, pyelonephritis, pelvic inflammatory disease) and some nonurogenital infections, in which their role is not clear.
Mycoplasma hominis
M. hominis and Ureaplasma species are commensal organisms that are part of the normal flora of the lining of the urogenital tracts. However, they can spread and cause infections in patients in whom the mucosal lining is damaged (eg, due to trauma or iatrogenic procedures), in premature infants, or in immunocompromised patients.
