High prevalence of azithromycin resistance to Treponema pallidum in geographically different areas in China

Treatment with effective antibiotics is one important strategy for syphilis control in China. This study aimed to evaluate the prevalence of azithromycin resistance to T. pallidum in China. A cross-sectional study was conducted among 391 patients with early syphilis recruited from STD clinics in eight cities during October 2008 and October 2011. The swabs were obtained from the moist lesions of the participating patients. A touchdown/nested PCR of the 23S ribosomal RNA (rRNA) gene was performed on DNA samples extracted from these specimens. The presence or absence of the A2058G point mutation, conferring resistance to azithromycin, was determined by restriction enzyme digestion analysis of the PCR amplicon by MboII. Two hundred and eleven patients with primary or secondary syphilis were found to have T. pallidum DNA in their moist lesions by PCR assays. The A2058G mutation was present in 91.9% (194/211, 95% CI, 87.2-95.1%) of these patients, with no significant differences noted between patients from the eastern part (93.8%), southern part (88.6%) and northern part (95.2%) of China (χ(2) = 2.303, p 0.316). Compared with patients who had not taken macrolides in previous years before study entry, the patients who had taken the antibiotics had a significantly higher prevalence of azithromycin resistance (97.0% vs. 62.5%), with an odds ratio of 19.65 (95% CI, 5.77-66.93). It can be concluded that prevalence of azithromycin resistance is substantial in China and consequently that the macrolides should not be used as a treatment option for early or incubating syphilis in China.