[1] Univ Colorado Denver, Div Gastroenterol & Hepatol, Dept Med, Aurora, CO 80045 USA
[2] Univ Colorado Denver, Div Pulm Sci & Crit Care Med, Dept Med, Aurora, CO USA
[3] Univ Colorado Denver, Dept Microbiol & Immunol, Aurora, CO 80045 USA
[4] Denver Vet Affairs Med Ctr, Denver, CO 80220 USA