Diagnostic methods for intracellular pathogens.
Diagnosis of infection with Chlamydia pneumoniae is difficult and the optimal diagnostic procedure has yet to be established. C. pneumoniae is more difficult to isolate in tissue culture than C. trachomatis. Attention must be paid to the site from which the specimen is taken, and all specimens should be processed within 24 h or stored at 4 C. Serologic diagnosis largely depends on microimmunofluorescence testing which, despite proposed criteria, still has a large subjective component. Serology has limitations in terms of both sensitivity and specificity and antibodies may be difficult to detect in individuals with positive C. pneumoniae cultures. Non-culture methods include enzyme immunoassays, fluorescent-antibody techniques and DNA probes. The most promising appears to be PCR. Co-infection of C. pneumoniae and other respiratory organisms seem to be common.