[1] Univ Calif Los Angeles, Harbor Res & Educ Inst, Div Infect Dis, Torrance, CA 90502 USA
[2] Georgetown Univ, Med Ctr, Sch Med, Dept Microbiol & Immunol, Washington, DC 20007 USA
[3] Univ Calif Los Angeles, Sch Med, Dept Pathol, Los Angeles, CA 90024 USA
[4] Univ Calif Los Angeles, Sch Med, Dept Med, Los Angeles, CA 90024 USA