日本性感染症学会誌 Journal of Japanese Society for Sexually Transmitted Infections

A man (MSM) in his 40s was first infected with genital herpes ten years ago, who experienced recurrence of the infection every three to four years. He came to our clinic for HIV pre-exposure prophylaxis, and his screening test was qualitatively positive for TP antibodies for syphilis and negative for RPR. Penile lesion was confirmed, which was suspected to be a recurrence of herpes, and it was found that the ulcer had become epithelialized, leaving induration and redness. The patient had no previous treatment for syphilis, and none of the four men with whom he had recently had sexual intercourse had symptoms of syphilis. His TPLA antibody titer was 181.1 T.U., and RPR titer was under 0.2 R.U. FTA-ABS was tested because it was challenging to distinguish between TP antibody-suspiciously positive herpes and first syphilis infection with hard chancre; FTA-ABS: 5x (2+), 20x (2+) positive result, diagnosis of syphilis was made and the patient was treated with 2.4 million units of benzylpenicillin. RPR remained negative following treatment, and TP antibodies fluctuated somewhat up and down: 172.5 T.U. after 2 weeks of treatment, 271.9 after 6 weeks, 162.2 after 3 months, 307.7 after 4 months, and 258.6 after 5 months. A blister formed on the penis after 5.5 months, and TP antibody was measured, but it had decreased to 170.9 T.U., and symptoms improved with oral administration of valacyclovir. FTA-ABS is useful in RPR-negative TP antibody-positive cases that are difficult to differentiate from herpes infection or other diseases.