Long-term dynamics of the “Serratia marcescenscomplex” in the hospital-built environment

Abstract

Serratia marcescensis an opportunistic pathogen historically associated with abrupt, unpredictable, and severe outbreaks in hospital intensive care units (ICUs) and, more recently, with the spread of acquired genes encoding carbapenem resistance. However, the population biology and ecology ofS. marcescensin the hospital ecosystem is still poorly understood. Here, we combine epidemiological information of 1417Serratiaisolates collected from the sinks of a large ICU ward that underwent significant demographic and operational changes (2019-2020) and 99 non-redundant outbreak/non-outbreak isolates from the same hospital (2003-2019), with genomic data of 165 isolates. We first report hospital sinks as reservoirs of heterogeneous and coexistent populations of theS. marcescens complex(SMC). A novel SMC clade congruent with the recently describedSerratia neveispecies is predominant, exhibiting chromosomal AmpC β-lactamase with an unusual basal expression in contrast to one of the major features ofS. marcescens. PersistentSerratiasink strains are identical to those involved in clonal and polyclonal outbreaks of VIM-1 and OXA-48 producers since at least 2017. The 'source-sink' dynamics of SMC populations able to acquire the highly conserved plasmids such as IncL carryingblaVIM-1 orblaOXA-48 offer novel insights that might improve interventions to control outbreaks and treatSerratiainfections in high-risk hospital areas.

A long-term survey of Serratia spp. bloodstream infections revealed an increase of antimicrobial resistance involving adult population

“…The WGS comparative analysis confirmed that six Serratia spp. BSI isolates (VIM-1 producers recovered during the last years of studied period) carried the IncL/M plasmid, harboring the same class I integron with bla VIM-1 carbapenemase gene, which had been found in previous studies from our institution ( 13 , 16 ), suggesting a considerable ability to persist ( 24 ).…”