EVALUATION OF 2 NONCULTURE ANTIGEN TESTS AND 3 SEROTESTS FOR DETECTION OF ANTI-CHLAMYDIAL ANTIBODIES IN THE DIAGNOSIS OF OCULAR CHLAMYDIAL INFECTIONS

Background: Diagnosis of chlamydial conjunctivitis is difficult in chr onic diseases because chlamydial elementary bodies are mostly undetect able in conjunctival scrapings by cell culture. We therefore compared two nonculture antigen tests and three different serotests for anti-ch lamydial antibodies with McCoy cell culture, the ''gold standard'' of chlamydial diagnosis. Conjunctival scrapings and serum samples of 93 p atients attending the outpatient eye clinic in Graz because of chronic follicular conjunctivitis were tested. Methods: A total of 558 conjun ctival scrapings and 93 serum samples were investigated. Chlamydial an tigen detection was done by McCoy cell culture, polymerase chain react ion (PCR; Amplicor, Roche), and direct immunofluorescence assay (DFA; Microtrak, Syva). Antichlamydial IgA and IgG antibodies in the sera we re detected by an immunoperoxidase assay (IPAzyme, Savyon) and two dif ferent enzyme-linked immunosorbent assays (SeroELISA, Savyon and rELIS A, medac). Results: Cell culture and PCR yielded identical results. Th e positivity rate for chlamydial conjunctivitis was 8.6% (8 of 93 pati ents). PCR proved most sensitive and most specific. IPAzyme was 75% se nsitive for IgA and 100% for IgG; SeroELISA and rELISA were less sensi tive. IPAzyme was 81% specific for IgA and 47.3% for IgG. SeroELISA an d rELISA were less specific for IgA, but more specific for IgG. Post-t est likelihood of disease was greatest in IPAzyme. Conclusions: PCR pr oved to be a good alternative to cell culture; DFA is useful for quick diagnosis. Genus-specific serotests cannot compete with chlamydial an tigen detection. They differ in sensitivity and specificity because of the antigen type they present. They are still of only supportive valu e in cases where chlamydial antigen detection is not possible. Recentl y introduced species-specific antibody tests should be of greater valu e.