Rapid detection of specific treponemal antibodies by counterimmunoelectrophoresis using an extract of Treponema pallidum.

Specific treponemal antibodies were detected in small amounts by counterimmunoelectrophoresis (CIE) in agar gel, using an extract of Treponema pallidum. The T. pallidum-CIE test was compared with the fluorescent treponemal antibody-absorption (FTA-ABS) test and with the Reiter protein complement fixation (RPCF) test. The results of the T. pallidum-CIE and FTA-ABS tests agreed in 96% of cases. There was no agreement between the T. pallidum-CIE and RPCF tests in 14% of cases. The three tests were compared in 56 sera--17 from cases of untreated syphilis and 39 from biologically false positive (BFP) reactors. RPCF was positive in 10 (59%) of the 17 specimens from cases of untreated syphilis; all 17 sera were FTA-ABS positive. The T. pallidum-CIE test was positive in 14 (82%) of the 17 specimens. All of the 39 BFP reactors, positive by the RPCF test, were shown to be negative by the FTA-ABS and T. pallidum-CIE tests. These results suggest that the T. pallidum-CIE test is more specific than the RPCF test and slightly less specific than the FTA-ABS test. The advantages of the T. pallidum-CIE test as a convenient method are speed of performance, simplicity and economy.