Molecular Characterization by Whole-Genome Sequencing of Clinical and Environmental Serratia marcescens Strains Isolated during an Outbreak in a Neonatal Intensive Care Unit (NICU)

• Published in: Diagnostics (Basel) Vol. 12; no. 9; p. 2180
• Main Authors: Piccirilli, Alessandra, Cherubini, Sabrina, Brisdelli, Fabrizia, Fazii, Paolo, Stanziale, Andrea, Di Valerio, Susanna, Chiavaroli, Valentina, Principe, Luigi, Perilli, Mariagrazia
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 09.09.2022; MDPI
• Subjects: antibiotic resistance genes; Antibiotics; Antimicrobial agents; Asymptomatic; Communication; Drug resistance; Enzymes; Epidemics; Genes; Genomes; Gestational age; Hospitals; Intensive care; Medical equipment; Newborn babies; Nosocomial infections; S. marcescens; Virulence; WGS; United States > US; Italy
• ISSN: 2075-4418; 2075-4418
• DOI: 10.3390/diagnostics12092180

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.