Comparison of minocycline and azithromycin for the treatment of mild scrub typhus in northern China

• Scrub typhus is an acute febrile illness caused by infection with Orientia tsutsugamushi.
• Minocycline is more active than azithromycin against O. tsutsugamushi infection in northern China.
• Both minocycline and azithromycin are safe for the treatment of mild scrub typhus.
• The findings provide valuable information for the treatment of mild scrub typhus.

Scrub typhus, caused by Orientia tsutsugamushi, has recently emerged in northern China where the disease had not been known to exist. Although doxycycline and azithromycin are the recommended agents for the treatment of scrub typhus, clinical responses depend both on the susceptibilities of various O. tsutsugamushi strains and the severity of the disease. A retrospective analysis was conducted on patients diagnosed with mild scrub typhus from August 2013 to January 2016 in the Affiliated Hospital of Nantong University, northern China. A total of 40 patients who received minocycline treatment and 34 patients who received azithromycin treatment were included in the analysis. All patients except one defervesced within 120 h after initiating antimicrobial therapy. Kaplan–Meier curves in association with log-rank test showed that the median time to defervescence was significantly shorter for the minocycline-treated group than the azithromycin-treated group (P = 0.003). There were no serious adverse events during treatment. No relapse occurred in either group during the 1-month follow-up period. In conclusion, both minocycline and azithromycin are effective and safe for the treatment of mild scrub typhus, but minocycline is more active than azithromycin against O. tsutsugamushi infection acquired in northern China.