Mycoplasmas are ubiquitous bacteria that differ from other prokaryotes in that they lack a cell wall.
Mycoplasma pneumoniae is a common cause of pneumonia, particularly community-acquired pneumonia.
Increasing evidence suggests that M. genitalium and Ureaplasma urealyticum cause some cases of 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, but whether they cause these infections is not clear.
Mycoplasmas are not visible with light microscopy. Culture is technically difficult and often unavailable, but laboratory diagnosis is sometimes possible with nucleic acid amplification tests (NAATs) or by detection of antibodies; frequently, diagnosis must be by exclusion. One NAAT for M. pneumoniae is part of a commercially available panel that tests for multiple respiratory pathogens.
Macrolides are usually the antimicrobials of choice. Most species are also sensitive to fluoroquinolones and tetracyclines. Macrolide-resistant infections have been reported; therefore, fluoroquinolones or tetracyclines should be considered in patients with refractory disease, especially in areas with significant macrolide resistance.