Molecular Characterization by Whole-Genome Sequencing of Clinical and Environmental <i>Serratia marcescens</i> Strains Isolated during an Outbreak in a Neonatal Intensive Care Unit (NICU)
Alessandra Piccirilli,
Sabrina Cherubini,
Fabrizia Brisdelli,
Paolo Fazii,
Andrea Stanziale,
Susanna Di Valerio,
Valentina Chiavaroli,
Luigi Principe,
Mariagrazia Perilli
Affiliations
Alessandra Piccirilli
Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
Sabrina Cherubini
Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
Fabrizia Brisdelli
Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
Paolo Fazii
Clinical Microbiology and Virology Unit, Pescara Public Hospital, 65122 Pescara, Italy
Andrea Stanziale
Clinical Microbiology and Virology Unit, Pescara Public Hospital, 65122 Pescara, Italy
Susanna Di Valerio
Neonatal Intensive Care Unit, Pescara Public Hospital, 65123 Pescara, Italy
Valentina Chiavaroli
Neonatal Intensive Care Unit, Pescara Public Hospital, 65123 Pescara, Italy
Luigi Principe
Clinical Pathology and Microbiology Unit, “S. Giovanni di Dio” Hospital, 88900 Crotone, Italy
Mariagrazia Perilli
Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
The whole-genome sequencing (WGS) of eighteen S. marcescens clinical strains isolated from 18 newborns hospitalized in the Neonatal Intensive Care Unit (NICU) at Pescara Public Hospital, Italy, was compared with that of S. marcescens isolated from cradles surfaces in the same ward. The identical antibiotic resistance genes (ARGs) and virulence factors were found in both clinical and environmental S. marcescens strains. The aac(6′)-Ic, tetA(41), blaSRT-3, adeFGH, rsmA, and PBP3 (D350N) genes were identified in all strains. The SRT-3 enzyme, which exhibited 10 amino acid substitutions with respect to SST-1, the constitutive AmpC β-lactamase in S. marcescens, was partially purified and tested against some β-lactams. It showed a good activity against cefazolin. Both clinical and environmental S. marcescens strains exhibited susceptibility to all antibiotics tested, with the exception of amoxicillin/clavulanate.
