Multi-center evaluation of the Abbott IMx Select(®) chlamydia assay for detection of Chlamydia trachomatis in female endocervical and male urethral swabs

The IMx Chlamydia, an automated one hour objective enzyme immunoassay, was evaluated for the detection of chlamydial antigen in 1,776 clinical specimens. IMx performance was compared to cell culture. Female sensitivity (sens.) was 90.8% (138/152) and specificity (spec.) was 97.4%(1108/1137). Male sens. was 80.5% (66/82) and spec. was 95.3% (386/405). Discordant analysis was performed by direct fluorescent antibody or polymerase chain reaction. After discordant analysis, the resolved female sens. and spec. were 91.8% and 99.1%, respectively. The positive (PPV) and the negative (NPV) predictive values were 94.0% and 98.8%, respectively. The resolved male sens. and spec. were 83.8% and 99.5%, respectively. The PPV and NPV values were 97.6% and 96.0%, respectively. Within run precision ranged from 3.3 to 9.1% CV. IMx is a rapid, highly sensitive, and precise assay for the detection of chlamydial infections.