Chlamydia trachomatis strains show specific clustering for men who have sex with men compared to heterosexual populations in Sweden, the Netherlands, and the United States.

Christerson L, Bom RJ, Bruisten SM, Yass R, Hardick J, Bratt G, Gaydos CA, Morré SA, Herrmann B.
J Clin Microbiol. 2012 Nov;50(11):3548-55. doi: 10.1128/JCM.01713-12.