Mycoplasma pneumoniae is the only mycoplasma clearly involved in respiratory tract infections in man. Implicated most often in tracheobronchitis, it is the second most frequent agent responsible for comm-unity-wide bacterial pneumonia, and in addition it probably causes asthma exacerbations. M. pneumoniae infection occurs endemically, with epidemic peaks every 4-7 years, mostly in children above five years of age. The laboratory diagnosis of these infections, mainly by serology, is made only in severe cases because of the fastidious growth of this microorganism. M. pneumoniae can, however, be detected easily by molecular amplification techniques. Macrolides and related antibiotics are considered the treatment of choice for M. pneumoniae infection in both adults and children. Antibiotic sensitivity testing of M. pneumoniae is not done routinely because resistant isolates have only rarely been described, the results are delayed, and they have no immediate therapeutic consequence. (C) 2007 Elsevier Masson SAS. Tons droits reserves.