[1] Louis Stokes Cleveland Vet Affairs Med Ctr, Res Serv, Cleveland, OH USA
[2] Louis Stokes Cleveland Vet Affairs Med Ctr, Infect Control Dept, Cleveland, OH USA
[3] Univ Hosp Cleveland, Dept Med, Cleveland, OH 44106 USA
[4] Case Western Reserve Univ, Sch Med, Dept Epidemiol & Biostat, Cleveland, OH 44106 USA