1. Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
2. Division of Infectious Diseases, UPMC, Pittsburgh, Pennsylvania, USA
3. Division of Hospital Epidemiology and Infection Control, UPMC, Pittsburgh, Pennsylvania, USA
4. Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania, USA
5. University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
6. Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
7. Wolff Center, UPMC, Pittsburgh, Pennsylvania, USA