1 Division of Infectious Diseases, Children's Hospital of Philadelphia, PA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA; Department of Infection Prevention and Control, Children's Hospital of Philadelphia, PA. Electronic address: kitte@chop.edu.
2 Division of Infectious Diseases, Children's Hospital of Philadelphia, PA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA; Department of Infection Prevention and Control, Children's Hospital of Philadelphia, PA.