[1] Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Vatche & Tamar Manoukian Div Digest Dis, 11301 Wilshire Blvd, Los Angeles, CA 90073 USA
[2] VA Greater Los Angeles Healthcare Syst, Div Gastroenterol Hepatol & Parenteral Nutr, Los Angeles, CA USA
[3] VA Greater Los Angeles Healthcare Syst, Div Infect Dis, Los Angeles, CA USA
[4] Univ Calif Los Angeles, David Geffen Sch Med, Los Angeles, CA 90073 USA
[5] Univ Calif Los Angeles, David Geffen Sch Med, Div Infect Dis, Dept Med, Los Angeles, CA 90073 USA