Architectural interventions to mitigate the spread of SARS-CoV-2 in emergency departments.

INTRODUCTION: Emergency departments (EDs) are a critical entry gate for infectious agents into hospitals. In this interdisciplinary study, we explore how infection prevention and control (IPC) architectural interventions mitigate the spread of emerging respiratory pathogens using the example of SARS-CoV-2 in a prototypical ED. METHODS: Using an agent-based approach, we integrated data on patients' and healthcare workers' (HCWs) routines and the architectural characteristics of key ED areas. We estimated the number of transmissions in the ED by modelling the interactions between and among patients and HCWs. Architectural interventions were guided towards the gradual separation of pathogen carriers, compliance with a minimum interpersonal distance, and deconcentrating airborne pathogens (higher air exchange rates (AERs)). Interventions were epidemiologically evaluated for their mitigation effects on diverse endpoints. RESULTS: Simulation results indicated that higher AERs in the ED (compared with baseline) may provide a moderate level of infection mitigation (incidence rate ratio (IRR) of 0.95 (95% confidence interval (CI) 0.93-0.98)) while the overall burden decreased more when rooms in examination areas were separated (IRR of 0.78 (95% CI 0.76-0.81)) or when the size of the ED base was increased (IRR of 0.79 (95% CI 0.78-0.81)). The reduction in SARS-CoV-2-associated nosocomial transmissions was largest when architectural interventions were combined (IRR of 0.61 (95% CI 0.59-0.63)). CONCLUSIONS: These modelling results highlight the importance of IPC architectural interventions; they can be devised independently of profound knowledge of an emerging pathogen, focusing on technical, constructive, and functional components. These results may inform public health decision-makers and hospital architects on how IPC architectural interventions can be optimally used in healthcare premises.

Genetic analysis of the biosynthesis of non-ribosomal peptide- and polyketide-like antibiotics, iron uptake and biofilm formation by Bacillus subtilis A1/3.

The Bacillus subtilis strain A1/3 shows exceptionally diverse antibiotic capacities compared to other B. subtilis strains. To analyze this phenomenon, mutants for the putative pantotheinyltransferase gene (pptS), and for several genes involved in non-ribosomal peptide synthesis and polyketide synthesis were constructed and characterized, using bioassays with blood cells, bacterial and fungal cells, and mass spectrometry. Among at least nine distinct bioactive compounds, five antibiotics and one siderophore activity were identified. The anti-fungal and hemolytic activities of strain A1/3 could be eliminated by mutation of the fen and srf genes essential for the synthesis of fengycins and surfactins. Both pptS- and dhb -type mutants were defective in iron uptake, indicating an inability to produce a 2,3-dihydroxybenzoate-type iron siderophore. Transposon mutants in the malonyl CoA transacylase gene resulted in the loss of hemolytic and anti-fungal activities due to the inhibition of bacillomycin L synthesis, and this led to the discovery of bmyLD-LA-LB* genes. In mutants bearing disruption mutations in polyketide (pksM- and/or pksR -like) genes, the biosynthesis of bacillaene and difficidins, respectively, was inactivated and was accompanied by the loss of discrete antibacterial activities. The formation of biofilms (pellicles) was shown to require the production of surfactins, but no other lipopeptides, indicating that surfactins serve specific developmental functions.

Diversity of polyamine patterns in soft rot pathogens and other plant-associated members of the Enterobacteriaceae.

Polyamine profiles of 91 pectolytic and other plant-associated strains from 30 taxa of the Enterobacteriaceae were obtained by gradient high performance liquid chromatography (HPLC). Pectobacterium carotovorum, basonym Erwinia carotovora, contained a high amount of putrescine and less diaminopropane. Diaminopropane was absent in Pectobacterium chrysanthemi, basonym E. chrysanthemi, whereas cadaverine was present in addition to the major compound putrescine. This chemotaxonomic difference reflects the deepest phylogenetic branching point within the recently emended genus Pectobacterium which lies between the two species P. carotovorum and P. chrysanthemi. Both important soft rot pathogens are easily distinguishable from each other and from the type species of the genus Erwinia as diaminopropane is the only major polyamine compound in E. amylovora. Chemotaxonomic heterogeneity is also emerging with respect to DYE's Amylovora group proposed in an early phytopathological concept.