[1] Thammasart Univ Hosp, Fac Med, Div Infect Dis, Pathum Thani 12121, Thailand
[2] Siriraj Hosp, Fac Med, Div Microbiol, Bangkok, Thailand
[3] Thai Natl Inst Hlth, Dept Sci, Nonthaburi, Thailand
[4] St Louis Univ, Sch Publ Hlth, St Louis, MO 63103 USA