High prevalence of macrolide resistant Treponema pallidum strains in a London centre.

OBJECTIVES Macrolide resistant Treponema pallidum strains, caused by mutations in the 23S ribosomal RNA (23S rRNA) gene, are widespread and increasingly prevalent. The authors aimed to establish the strain types of T pallidum isolated from patients in a London sexual health centre and to determine the frequency of macrolide resistance. METHODS T pallidum DNA from blood and ulcer samples were subjected to strain typing and mutation analysis using previously described methods. RESULTS 18 samples were tested and a 23S rRNA point mutation conferring macrolide resistance was found in 66.6%. All resistant strains were collected from men who have sex with men and both the A2058G and the A2059G mutations were found. Two strain types were identified (14d/g and 14d/f); the predominant strain type was 14d/g and an association was noted between tp0548 type g and macrolide resistance. CONCLUSIONS High levels of T pallidum macrolide resistance are present in London, UK, and this has clear implications for national treatment guidelines.