title: The management of isolated positive syphilis enzyme immunoassay results in HIV-negative patients attending a sexual health clinic.
abstract: An unconfirmed positive treponemal enzyme immunoassay (enzyme immunoassay positive, Treponema pallidum particle agglutination negative and rapid plasma reagin negative) presents a clinical challenge to distinguish early syphilis infection from false-positive results. These cases are referred for syphilis line assay (INNO-LIA) and recalled for repeat syphilis serology. We performed a retrospective audit to establish the proportion of HIV-negative cases with unconfirmed positive enzyme immunoassay results, the proportion of these cases that received an INNO-LIA test and repeat syphilis serology testing and reviewed the clinical outcomes; 0.35% (80/22687) cases had an unconfirmed positive treponemal enzyme immunoassay result. Repeat syphilis serology was performed in 80% (64/80) cases, but no additional cases of syphilis were identified. Eighty-eight per cent (70/80) received an INNO-LIA test; 14% (5/37) unconfirmed enzyme immunoassay-positive cases with no prior history of syphilis were confirmed on INNO-LIA assay, supporting a diagnosis of latent syphilis. As a confirmatory treponemal test, the INNO-LIA assay may be more useful than repeat syphilis serological testing.
authors.affiliation: Department of Sexual health, University Hospitals Birmingham NHS Foundation Trust, Whittall Street Sexual Health Clinic, Birmingham, UK nicolathorley@icloud.com.
authors.forename: Nicola
authors.initials: N
authors.lastname: Thorley
authors.affiliation: Department of Sexual health, University Hospitals Birmingham NHS Foundation Trust, Whittall Street Sexual Health Clinic, Birmingham, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Adebayo
authors.affiliation: Department of Microbiology, University Hospitals Birmingham NHS Foundation Trust and Public Health England, Public Health Laboratory Birmingham, Heartlands Hospital, Birmingham, UK.
authors.forename: Erasmus
authors.initials: E
authors.lastname: Smit
authors.affiliation: Department of Sexual health, University Hospitals Birmingham NHS Foundation Trust, Whittall Street Sexual Health Clinic, Birmingham, UK.
authors.forename: Keith
authors.initials: K
authors.lastname: Radcliffe
mesh_terms: D000328:Adult; D000554:Ambulatory Care Facilities; D005260:Female; D018023:HIV Seronegativity; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D008297:Male; D008485:Medical Audit; D060728:Reproductive Health; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013587:Syphilis / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D013588:Syphilis Serodiagnosis / Q000379:methods*; D014210:Treponema pallidum / Q000276:immunology* / Q000302:isolation & purification; D006113:United Kingdom / Q000453:epidemiology
keywords: HIV negative; Treponema pallidum; diagnosis; isolated positive enzyme immunoassay; sexual health; sexually transmitted infection; syphilis; syphilis serology; unconfirmed EIA