Chlamydia pneumoniae and Mycoplasma pneumoniae.

Mycoplasma pneumoniae infection occurs worldwide and is the most common cause of community-acquired pneumonia (CAP) in 5- to 20-year-olds. The most reliable diagnostic test is the enzyme immunoassay, which allows immunoglobulin (Ig)G and IgM titration and presents 92% sensitivity and 95% specificity on paired samples. Potentially active drugs are tetracyclines, macrolides, ketolides, lincosamides, streptogamines, chloramphenicol, and fluoroquinolones. Chlamydia pneumoniae accounts for 6 to 20% of CAP cases, depending on several factors such as setting of the studied population, age group examined, and diagnostic methods used. The current gold standard for serological diagnosis of acute infection is microimmunofluorescence testing. Tetracyclines and erythromycin show good in vitro activity and so far have been the most commonly employed drugs in the treatment of C. pneumoniae infection. New macrolides, ketolides, and new fluoroquinolones are other potentially effective drugs.