Persistence of Treponema pallidum following penicillin G therapy. Report of two cases.

The isolation of Treponema pallidum from cerebrospinal fluid (CSF) obtained from two adult patients, both of whom had normal CSF values except for positive fluorescent treponemal antibody-absorption (FTA-ABS) tests and both of whom had received currently recommended courses of penicillin, raises important considerations in the treatment of neurosyphilis in adults.