1. Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
2. Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48864, United States
3. Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
4. Tennessee Valley Healthcare Systems, Department of Veterans Affairs, Nashville, Tennessee 37212, United States