[1] Duke Univ, Div Infect Dis, Dept Med, Med Ctr, Durham, NC 27710 USA
[2] Duke Infect Control Outreach Network, Durham, NC USA
[3] Durham Vet Affairs Med Ctr, Durham, NC USA
[4] Univ N Carolina, Sch Med, Dept Med, Div Infect Dis, Chapel Hill, NC USA