Syphilis Co-Infection Among People Living with HIV in Romania: Epidemiological and Clinical Characteristics in a Single-Center Retrospective Study

Syphilis and HIV are sexually transmitted disease (STDs) that interact synergistically. However, data on HIV–syphilis co-infection in Romania remain limited. We conducted a retrospective cohort study at a single Romanian HIV/AIDS Day Clinic, including 439 adult people living with HIV (PLWH) monitored between 2020 and 2025. Demographic, epidemiological, clinical, and laboratory data were collected, including HIV staging and syphilis history. Syphilis co-infection was identified in 81 patients (18.5%), and 61.5% met criteria for AIDS. Viral suppression was achieved in 82.2%, and 78.4% achieved CD4 counts >350 cells/mm3. Male sex, urban residence, unmarried status, sexual HIV transmission, genital condyloma, and other STIs were independently associated with syphilis. First episodes of syphilis were predominantly secondary (61%), neurosyphilis was present in 5%, and serofast evolution occurred in 12%, more frequently after reinfection. Among deceased patients, 20.9% had a history of syphilis, but co-infection was not significantly associated with mortality. Nine of 28 patients lost to follow-up had prior syphilis, suggesting a potential impact on retention in care. These findings indicate that HIV–syphilis co-infection is increasingly prevalent in Romania, driven primarily by behavioral factors, and highlight the need for targeted STD screening and prevention strategies among high-risk PLWH.