[1] Univ Colorado, Dept Med, Div Infect Dis, Denver, CO 80202 USA
[2] CDC, Epidem Intelligence Serv, Atlanta, GA 30333 USA
[3] Colorado Dept Publ Hlth & Environm, Denver, CO USA
[4] Univ Colorado, Div Pulm Sci & Crit Care Med, Denver, CO 80202 USA
[5] Univ Colorado, Dept Med, Denver, CO USA
[6] Denver Hlth, Denver, CO USA