Comparison of methods for the detection of treponema pallidum in lesions of early syphilis.

BACKGROUND

The clinical diagnosis of primary and secondary syphilis can be difficult because of the wide variability of lesions. The available laboratory tests (dark-field microscopy and direct fluorescent antibody) require specialized microscopes and skilled technicians, and serologic tests are insensitive in early infection.

METHODS

Dark-field microscopy and monoclonal antibody staining were compared to a new solid-phase enzyme-linked immunosorbent assay (Visuwell test) for detection of T. pallidum in lesion exudate of 188 patients with genital lesions.

RESULTS

Sixty-four patients (34%) had lesions of early syphilis diagnosed 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 monoclonal antibody staining technique demonstrated the presence of T. pallidum in 59 (92.2%) of the 64 patients. The Visuwell test gave a negative result in 111 of 124 patients who had negative dark-field and direct fluorescent antibody test results (89.5% specificity).

CONCLUSIONS

The Visuwell test is an alternative method for evaluating genital ulcers but is less sensitive and specific than existing tests.