(P114) PILOT STUDY OF LINEZOLID FOR EARLY SYPHILIS TREATMENT

Background:
Syphilis, a genital ulcerative disease, remains a prominent sexually transmitted disease that disproportionately affects men who have sex with men (MSM) and increasingly cis-gender women. Linezolid is an FDA-approved, safe, low-cost, oral antibiotic that crosses the blood-brain barrier. A recent study showed that linezolid 600 mg, once a day for five days, was 70% effective in treating syphilis cases, showing that longer duration treatment may be necessary. We aimed to assess the efficacy of linezolid 600mg, twice a day for 10 days for the treatment of early syphilis.

Methods:
We are conducting a randomized, non-comparative, pilot study. We aim to enroll a total of 24 patients (18 linezolid, 6 penicillin) with early syphilis from Chicago, Illinois, and Jackson, Mississippi. The experimental arm receives oral linezolid 600 mg twice daily for ten days, while the control arm receives benzathine penicillin G 2.4 million units intramuscularly once. The main outcome is a ≥4-fold RPR titer decline by 180 days after treatment. Participants are monitored for clinical outcomes and serological response with 1-month, 3-month, and 6-month follow-up visits after enrollment.

Results:
Currently, a total of six out of 24 participants are enrolled in the study; three are in the linezolid arm, and three are in the penicillin arm. All participants had early latent syphilis. All participants receiving linezolid adhered 100%. One penicillin participant (enrollment RPR 1:16, 3-month RPR 1:2) and one linezolid participant (enrollment RPR 1:64, 3-month RPR 1:16) completed their 3-month follow-up. No serious adverse reactions have been reported.

Conclusion:
Alternative treatment options for syphilis are urgently needed to address ongoing shortages of benzathine penicillin and for individuals allergic to penicillin.