Standardizing Chlamydia pneumoniae assays: Recommendations from the Centers for Disease Control and Prevention (USA) and the Laboratory Centre for Disease Control (Canada)

Chlamydia pneumoniae has been associated with atherosclerosis and several o ther chronic diseases, but reports from different laboratories are highly v ariable and "gold standards" are lacking, which has led to calls for more s tandardized approaches to diagnostic testing. Using leading researchers in the field, we reviewed the available approaches to serological testing, cul ture, DNA amplification, and tissue diagnostics to make specific recommenda tions. With regard to serological testing, only use of microimmunofluoresce nce is recommended, standardized definitions for "acute infection" and "pas t exposure" are proposed, and the use of single immunoglobulin (Ig) G titer s for determining acute infection and IgA for determining chronic infection are discouraged. Confirmation of a positive culture result requires propag ation of the isolate or confirmation by use of polymerase chain reaction (P CR). Four of 18 PCR assays described in published reports met the proposed validation criteria. More consistent use of control antibodies and tissues and improvement in skill at identifying staining artifacts are necessary to avoid false-positive results of immunohistochemical staining. These standa rds should be applied in future investigations and periodically modified as indicated.