[1] Karolinska Inst, Dept Med Huddinge, Unit Infect Dis, SE-17177 Stockholm, Sweden
[2] Uppsala Univ, Vastmanland Cty Hosp, Ctr Clin Res Vastmanland, Vasteras, Sweden
[3] Linkoping Univ, Fac Med & Hlth Sci, Linkoping, Sweden
[4] Univ Gothenburg, Sahlgrenska Acad, Inst Biomed, Dept Infect Dis, Gothenburg, Sweden
[5] Karolinska Univ Hosp Huddinge, Dept Obstet & Gynaecol, CLINTEC, Stockholm, Sweden
[6] Karolinska Inst, Dept Lab Med, Div Clin Microbiol, Stockholm, Sweden
[7] Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden