1 Department of Infectious Diseases "Santa Maria della Misericordia" Hospital, University of Perugia, Perugia Italy.
2 Department of Obstetrics and Gynecology "Santa Maria della Misericordia" Hospital, Perugia, Italy.
3 Division of Neonatology and Neonatal Intensive Care Unit, Department of Maternal and Child Health, Santa Maria della Misericordia Hospital of Perugia, Perugia, Italy.
4 Microbiology Unit, Department of Medicine, University of Perugia, Perugia, Italy.