The sensitivity of syphilis assays in detecting different stages of early syphilis

Abstract

Our aim was to determine the sensitivity of the Murex ICE enzyme immunoassay (EIA) as a screening test for early syphilis and to determine how many additional cases of infection were detected by performing additional tests when requested on clinical grounds. This was an observational study on consecutive patients diagnosed with syphilis in the Department of Genitourinary Medicine, Edinburgh between January 1st 2004 and April 1st 2005. Additional tests were performed on sera that gave a positive or equivocal EIA on screening as well as by clinical request on sera from contacts of syphilis, and those with clinical signs of syphilis. Additional tests included a Venereal Diseases Research Laboratory (VDRL) carbon antigen test, a Treponema pallidum particle agglutination (TPPA) test, INNO-LIA line immunoblot assay, and an EIA specific for anti-treponemal IgM.A total of 105 patients were diagnosed with syphilis: primary (50), secondary (26), early latent (8), and of unknown duration (21). The TPPA was the most sensitive test in primary syphilis and had a sensitivity of 96% (48/50), which was significantly higher (P <0.05) than the sensitivity of 84% (42/50) for the screening EIA: seven of the EIA negatives were detected by EIA-IgM, six by TPPA, five by immunoblot, and two by VDRL. EIA-IgM was negative in six primaries; all were positive by TPPA and immunoblot. We conclude that, in order to maximize the serological detection of primary syphilis a specific EIA-IgM test and a TPPA test should be performed whenever there is a clinical suspicion of primary infection. This is particularly important when an EIA such as Murex ICE is used as a single screening test as it is less sensitive than the TPPA in primary infection.

Characterization of Treponema pallidum Particle Agglutination Assay-Negative Sera following Screening by Treponemal Total Antibody Enzyme Immunoassays

“…It is highly desirable that a suitable confirmatory test should have, at least, sensitivity and specificity equivalent to those of the screening assay. Manavi and colleagues (16) have suggested that, in the absence of a specific treponemal IgM EIA, a TPPA test should be performed whenever there (Table 3). Traditionally, the FTA-ABS test is regarded as the "gold standard" for confirmatory syphilis serology (2,20).…”

The Architect Syphilis assay for antibodies to Treponema pallidum: an automated screening assay with high sensitivity in primary syphilis

“…In one study, 17 (34%) cases of primary syphilis were initially negative by EIA, which had a sensitivity of 57% when compared with dark ground microscopy 4. Another recent evaluation reported a sensitivity of 84% for the Murex immune capture enzyme (ICE) immunoassay in detecting primary syphilis 5. Commercially available EIAs vary in their ability to detect primary syphilis,6 7 Although dark ground microscopy has high sensitivity in the diagnosis of primary syphilis, it is not widely used and is only performed in 29% of cases nationally 3…”

Evaluation of the Determine Syphilis TP assay for the detection of antibodies against Treponema pallidum for the serodiagnosis of syphilis

“…In recent years, ELISAs and CLIAs have been developed and evaluated as treponemal diagnostic tests for syphilis, including the Murex Syphilis ICE test, the Architect Syphilis test, and others [7][8][9][10][11]; several of these assays are based on specific T. pallidum recombinant antigens. However, several limitations exist regarding the widespread use of these automated methods, such as the requirement for specialized techniques and equipment that are not commonly available in developing countries.…”