1. Division of Infectious Diseases, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
2. Department of Microbiology and Immunology, Meharry Medical College, Nashville, Tennessee, USA
3. Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
4. Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
5. Department of Veterans Affairs, Tennessee Valley Healthcare Systems, Nashville, Tennessee, USA