A Possible Outbreak by Serratia marcescens: Genetic Relatedness between Clinical and Environmental Strains.

Giuseppina Caggiano,Carlo Pazzani,Francesco Triggiano,Marco Lopuzzo,Adriana Mosca,Carla Calia,Pasquale Stefanizzi,Giusy Diella,Francesca Apollonio,Stefania Stolfa,Anna Maria Minicucci,Osvalda De Giglio,Giovanna Barbuti,Nicola Laforgia,Lidia Dalfino,Marta Oliva,Maria Teresa Montagna

doi:10.3390/ijerph18189814

Abstract

Serratia marcescens (SM) is a Gram-negative bacterium that is frequently found in the environment. Since 1913, when its pathogenicity was first demonstrated, the number of infections caused by SM has increased. There is ample evidence that SM causes nosocomial infections in immunocompromised or critically ill patients admitted to the intensive care units (ICUs), but also in newborns admitted to neonatal ICUs (NICUs). In this study, we evaluated the possible genetic correlation by PFGE between clinical and environmental SM strains from NICU and ICU and compared the genetic profile of clinical strains with strains isolated from patients admitted to other wards of the same hospital. We found distinct clonally related groups of SM strains circulating among different wards of a large university hospital. In particular, the clonal relationship between clinical and environmental strains in NICU and ICU 1 was highlighted. The identification of clonal relationships between clinical and environmental strains in the wards allowed identification of the epidemic and rapid implementation of adequate measures to stop the spread of SM.

Highlights

(4%, 3/75) in the neonatal ICUs (NICUs) were positive for Serratia marcescens (SM) and two (5%, 2/40) in intensive care units (ICUs) 1
In the NICU, one strain was isolated from a brush used before sterilization of surgical forceps and two from washbasins, while in ICU 1, the two strains were isolated from a book support and a faucet handle
22 SM strains were subjected to molecular investigations: 17 clinical strains and five environmental strains (Table 1)

Summary

Introduction

Serratia marcescens (SM) is a Gram-negative bacterium belonging to the family Enterobacterales that is commonly found in water, soil, animals, and plants [1,2]. SM was previously considered a saprophytic microorganism, its pathogenicity was demonstrated in 1913 [1,3] but, its role in the etiology of human infectious diseases was underestimated for many years [3]. The first outbreak of nosocomial infection caused by SM was confirmed in 1951, which aroused the interest of many researchers [3]. Reports of infections caused by SM increased. Some authors [1,3,4,5] have shown that SM causes nosocomial infections in immunocompromised or critically ill patients admitted to intensive care units (ICUs). Other authors have reported that SM colonizes the

Objectives

Methods

Results

Discussion

Conclusion