1. Division of Neurosurgery, Childrens Hospital of Los Angeles, and Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California
2. Department of Pathology, Childrens Hospital of Los Angeles, and Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California
3. Division of Microbiology, University of Nottingham, Nottingham, England