This month, Julia Bielicki from University Children’s Hospital Basel and St George’s University of London is reviewing:
Brooks B, Olm MR, Firek BA, et al. Strain-resolved analysis of hospital rooms and infants reveals overlap between the human and room microbiome. Nat Commun. 2017;8(1):1814. Published 2017 Nov 27.
What’s happening
Infant colonization by resistant bacteria is known to be an important risk factor for neonatal sepsis caused by these bacteria. The sources of bacteria are not entirely clear, but it is increasingly recognized that the hospital environment might be important in this regard. So far, few studies have looked into the genetic relatedness of bacteria found in the hospital environment and those colonizing babies in neonatal units. Further evidence on the exact role of the hospital or unit environment might have implications for appropriate infection prevention and control interventions.
What was done in this study?
The investigators extensively sampled frequently touched surfaces, other surfaces and sinks of six rooms of a neonatal unit in the US and subjected these samples to metagenomic sequencing. These metagenomes were compared to metagenomes from fecal samples of infants cared for in the rooms of interest. The laboratory analysis build on extensive preliminary work to ensure the successful recovery of high-quality genomes, also from environmental samples where the microbial biomass is typically low.
What was observed?
Two important observations were made in this study. First, the investigators were able to identify corroborating evidence for the existence of bacterial “room reservoirs”. Such reservoirs might explain why some other studies have identified genetically closely related strains in babies who were not on the unit at the same time, often having been hospitalized several years apart. Such reservoirs can be a source for reseeding of newly admitted babies and can sustain outbreaks in the face of extensive infection control measures. Second, the group found that closely related strains could be identified in infants hospitalized simultaneously and many weeks apart, presumably passing through the environment but also through healthcare providers’ hands. Similarly, several genetically identical strains were found in baby and room samples at the same time, with in some cases a clear directionality of transfer from an environmental source to the baby.
Does this apply to my unit?
Most likely, similar patterns would be found in most neonatal units. The investigators stress that the colonization of environmental niches plays a complex, and potentially somewhat secondary role in resistant bacterial acquisition on the neonatal unit. The study does not point towards any specific interventions that could be aimed at the neonatal unit environment, but the evidence presented suggests that supporting colonization resistance of key body sites, especially the gut, could offer important protection against colonization from low-biomass room reservoirs.