Generally antimicrobials for treatment of
pneumonia are chosen to target the usual bacterial etiological agents. Such regimens are unable to cure patients of
pneumonia caused by 'unusual organisms' mycoplasma, chlamydia, Pneumocystis carinii and Legionella pneumophilus). Thus, there is a need to anticipate their presence in appropriate cases and to plan the initial antimicrobial
therapy accordingly. Studies in Europe as well as India have shown that such
infections form a fairly substantial percentage of community acquired
pneumonia in children. Mycoplasma pneumoniae and Chlamydia pneumoniae are common in school age children while Chlamydia trachomatis occurs in early infancy. Pneumocystis carinii is an important pathogen in immunocompromised children. Routine laboratory tests and radiological features are not specific enough to give accurate diagnosis of these
infections for which one has to depend on sophisticated culture techniques, immunological tests for the
antigens or
antibodies and polymerase chain reaction. Mycoplasma, chlamydia and legionella
infections respond to
macrolide antibiotics and for
pneumocystis infections,
trimethoprim-sulfamethaxozole or
pentamidine is the
drug of choice. Overall prognosis with appropriate treatment is good except for P. carinii
infection in immunocompromised host which carries a high mortality and recurrence rate.