Tseng YT, Chou PY, Tai MH, et al. - As there is an uncertainty concerning the mechanism of Jarisch–Herxheimer reaction (JHR), an inflammatory reaction occurring after syphilis treatment, researchers sought to test their hypothesis that in syphilitic patients, CRP may be involved in the JHR at initial syphilis infection and also through interactions with benzathine penicillin-induced phagocytosis.

• A total of 29 syphilitic patients with/without JHR and three control groups (10 men who have sex with men (MSM) taking pre-exposure prophylaxis, 10 HIV-infected patients without syphilis, and 12 HIV-infected patients with previous syphilis) were enrolled in this prospective cohort study.

• All 29 syphilitic patients were MSM, and HIV infection was observed in 21 patients (72%).

• JHR development was identified in 41% (12/29) of the patients.

• Findings suggest a predictive value of a high baseline CRP level for JHR occurrence in syphilitic patients treated with benzathine penicillin.