1. Department of Medical Anesthesiology, College of Medicine and Health Sciences, University of Gondar, Kebele 16, P.O. Box 196, Gondar, Ethiopia
2. Department of Surgery, College of Medicine and Health Sciences, University of Gondar, Kebele 16, P.O. Box 196, Gondar, Ethiopia
3. Department of Medical Microbiology, College of Medicine and Health Sciences, University of Gondar, Kebele 16, P.O. Box 196, Gondar, Ethiopia