Pneumonia due to unusual organisms in children

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. (Indian J Pediatr 1999; 66 : 929-936).