[Colonization-outbreak of two clonally different strains of Serratia marcescens in a neonatal intensive care unit]

[Infection prevention in neonatal intensive care units]

In diesem Beitrag werden einige Besonderheiten der Infektionsprävention bei intensivmedizinisch behandelten Früh und Neugeborenen dargestellt. Ergänzend finden sich Hinweise zum krankenhaushygienischen Management der SARS-CoV-2(„severe acute respiratory syndrome coronavirus 2“)-Pandemie und zur Antibiotic Stewardship in der neonatologischen Intensivmedizin.

Illumina short-read and MinION long-read WGS to characterize the molecular epidemiology of an NDM-1 Serratia marcescens outbreak in Romania

Background and Objectives

Serratia marcescens is an emerging nosocomial pathogen, and the carbapenemase bla_NDM has been reported in several surveys in Romania. We aimed to investigate the molecular epidemiology of S. marcescens in two Romanian hospitals over 2010–15, including a neonatal NDM-1 S. marcescens outbreak.

Methods

Isolates were sequenced using Illumina technology together with carbapenem-non-susceptible NDM-1-positive and NDM-1-negative Klebsiella pneumoniae and Enterobacter cloacae to provide genomic context. A subset was sequenced with MinION to fully resolve NDM-1 plasmid structures. Resistance genes, plasmid replicons and ISs were identified in silico for all isolates; an annotated phylogeny was reconstructed for S. marcescens. Fully resolved study NDM-1 plasmid sequences were compared with the most closely related publicly available NDM-1 plasmid reference.

Results

44/45 isolates were successfully sequenced (S. marcescens, n = 33; K. pneumoniae, n = 7; E. cloacae, n = 4); 10 with MinION. The S. marcescens phylogeny demonstrated several discrete clusters of NDM-1-positive and -negative isolates. All NDM-1-positive isolates across species harboured a pKOX_NDM1-like plasmid; more detailed comparisons of the plasmid structures demonstrated a number of differences, but highlighted the largely conserved plasmid backbones across species and hospital sites.

Conclusions

The molecular epidemiology is most consistent with the importation of a pKOX_NDM1-like plasmid into Romania and its dissemination amongst K. pneumoniae/E. cloacae and subsequently S. marcescens across hospitals. The data suggested multiple acquisitions of this plasmid by S. marcescens in the two hospitals studied; transmission events within centres, including a large outbreak on the Targu Mures neonatal unit; and sharing of the pKOX_NDM1-like plasmid between species within outbreaks.

Outbreaks in the neonatal ICU: a review of the literature

PURPOSE OF REVIEW

Neonates in the neonatal ICU (NICU) are uniquely vulnerable to colonization and infection with pathogens such as multidrug resistant Gram-negative bacteria, which in turn are associated with increased infection-related morbidities and higher case-fatality rates. We reviewed the English, French, and German language literature published between 2015 and 2017, for reports of NICU outbreaks.

RECENT FINDINGS

A total of 39 outbreaks in NICUs were reported with Gram-negative bacteria (n = 21; 54%) causing most, and extended spectrum beta-lactamase-producing organisms being the most frequent resistance mechanism reported (n = 5). Five viral outbreaks were reported (respiratory syncytial virus = 3). A significant proportion of outbreaks (33%) did not identify a source. Whole genome sequencing was used more (n = 6 reports). The most common described infection prevention and control interventions included staff and parent education on hand hygiene, patient isolation, additional contact precautions, including discontinuation of 'kangaroo care', and cohorting. Reporting and publication bias are likely common.

SUMMARY

NICUs must be vigilant in identifying outbreaks, conduct comprehensive investigations, and implement targeted infection prevention and control strategies. Molecular epidemiology capacities are an essential element in outbreak investigation. More studies are needed to determine the added value of active colonization screening and their impact on outbreak development.