1 Infectious Disease Unit, 3rd Department of Pediatrics, Medical Faculty, Aristotle University School of Health Sciences, Hippokration General Hospital, Thessaloniki, Greece.
2 Pediatric Intensive Care Unit, Hippokration General Hospital, Thessaloniki, Greece.
3 Department of Hygiene and Epidemiology, Aristotle University of Thessaloniki, Thessaloniki, Greece.
4 Microbiology Department, Hippokration General Hospital, Thessaloniki, Greece.