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.