^aDepartment of Medicine, Division of Infectious Diseases, Feinberg School of Medicine, Northwestern University, Chicago, Illinois

^bDepartment of Medicine and Epidemiology, Division of Infectious Diseases and Geriatric Medicine, University of Colorado Anschutz Medical Center, Aurora, Colorado, USA

Correspondence to Kristine M. Erlandson, MD, MS, University of Colorado Anschutz Medical Center, 12700 E. 19th Avenue, Mail Stop B168, Aurora, CO 80045, USA. Tel: +1 303 724 4941; fax: +1 303 724 4926; e-mail: [email protected]