COMPARISON OF METHODS FOR THE DETECTION OF TREPONEMA-PALLIDUM IN LESIONS OF EARLY SYPHILIS

Background: The clinical diagnosis of primary and secondary syphilis c an be difficult because of the wide variability of lesions. The availa ble laboratory tests (dark-field microscopy and direct fluorescent ant ibody) require specialized microscopes and skilled technicians, and se rologic tests are insensitive in early infection. Methods: Dark-field microscopy and monoclonal antibody staining were compared to a new sol id-phase enzyme-linked immunosorbent assay (Visuwell test) for detecti on of T. pallidum in lesion exudate of 188 patients with genital lesio ns. Results: Sixty-four patients (34%) had lesions of early syphilis d iagnosed by either dark-field, monoclonal antibody staining, or both. The Visuwell test and dark-field examination were positive in 52 (81.3 %) and 55 (85.9%) of the 64 patients, respectively, whereas the monocl onal antibody staining technique demonstrated the presence of T. palli dum in 59 (92.2%) of the 64 patients. The Visuwell test gave a negativ e result in 111 of 124 patients who had negative dark-field and direct fluorescent antibody test results (89.5% specificity). Conclusions: T he Visuwell test is an alternative method for evaluating genital ulcer s but is less sensitive and specific than existing tests.