[1] Univ Penn, Perelman Sch Med, Dept Med, Div Gastroenterol, Philadelphia, PA 19104 USA
[2] Univ Penn, Perelman Sch Med, Dept Med, Div Infect Dis, Philadelphia, PA 19104 USA
[3] Univ Penn, Perelman Sch Med, Dept Pathol & Lab Med, Philadelphia, PA 19104 USA
[4] Hosp Univ Penn, Perioperat Serv, 3400 Spruce St, Philadelphia, PA 19104 USA