In 2001, Martin and colleagues12 published the first systematic evaluation of Mycoplasma and Chlamydophila infection in the upper and lower airways of adults with chronic, stable asthma. The investigators evaluated 55 stable asthmatic subjects and 11 healthy control subjects for the presence of M pneumoniae and C pneumoniae, performing serology, cultures, and polymerase chain reaction (PCR) for these organisms on specimens obtained from the nasopharynx and oropharynx, BAL, and endobronchial biopsy. M pneumoniae or C pneumoniae was detected by PCR in 56.4% of asthmatic subjects compared with 9% of control subjects (p = 0.02). Culture findings for both organisms were negative in all subjects. A total of 18 asthmatic subjects and 1 healthy control subject had serologic results that were positive for C pneumoniae. Of the 18 asthmatic subjects, 10 had positive results by IgG criteria and 5 had positive results by IgM criteria, with 3 of the subjects demonstrating both positive IgG and positive IgM criteria. However, only seven subjects had PCR results that were positive for C pneumoniae; of these, only three subjects had serologic results that were positive for C pneumoniae. On the basis of these data, the authors concluded that a majority of stable adults with chronic asthma are chronically infected with M pneumoniae, with a significantly greater frequency than nonasthmatic subjects, and that serologic evaluation does not reliably indicate lower airway PCR status.,12 At this time, more study is needed to evaluate whether Mycoplasma or Chlamydophila infection is a pathogenic factor in asthma or merely an epiphenomenon that is somehow related to the enhanced airway inflammation seen in subjects with chronic asthma.