Hyperosmotic Infusion and Oxidized Surfaces Are Essential for Biofilm Formation of Staphylococcus capitis From the Neonatal Intensive Care Unit.

Yue Qu,David R Cameron,Andrew Daley,Benjamin W Muir,Yali Li,Helmut Thissen,Minli Zhu,Xuebo Zhu,Anton Y Peleg,Christopher D Easton,John S Forsythe,Mario Salwiczek,Trevor Lithgow

doi:10.3389/fmicb.2020.00920

Abstract

Staphylococcus capitis is an opportunistic pathogen often implicated in bloodstream infections in the neonatal intensive care unit (NICU). This is assisted by its ability to form biofilms on indwelling central venous catheters (CVC), which are highly resistant to antibiotics and the immune system. We sought to understand the fundamentals of biofilm formation by S. capitis in the NICU, using seventeen clinical isolates including the endemic NRCS-A clone and assessing nine commercial and two modified polystyrene surfaces. S. capitis clinical isolates from the NICU initiated biofilm formation only in response to hyperosmotic conditions, followed by a developmental progression driven by icaADBC expression to establish mature biofilms, with polysaccharide being their major extracellular polymer substance (EPS) matrix component. Physicochemical features of the biomaterial surface, and in particular the level of the element oxygen present on the surface, significantly influenced biofilm development of S. capitis. A lack of highly oxidized carbon species on the surface prevented the immobilization of S. capitis EPS and the formation of mature biofilms. This information provides guidance in regard to the preparation of hyperosmolar total parenteral nutrition and the engineering of CVC surfaces that can minimize the risk of catheter-related bloodstream infections caused by S. capitis in the NICU.

Highlights

Premature newborns given intensive care and prolonged hospitalization in the neonatal intensive care unit (NICU) are peculiarly prone to infections, due to their immature immune system and invasive medical procedures such as catheterization (Beck-Sague et al, 1994)
Hyperosmotic Conditions Are Essential for S. capitis Biofilm Formation in the NICU
BD falcon Tissue Culture Polystyrene (TCPS) 96-well microplates were utilized for quantitative analysis of biofilm formation by 17 S. capitis isolates under different environmental conditions

Summary

Introduction

Premature newborns given intensive care and prolonged hospitalization in the neonatal intensive care unit (NICU) are peculiarly prone to infections, due to their immature immune system and invasive medical procedures such as catheterization (Beck-Sague et al, 1994). Factors Effecting S. capitis Biofilms line days (Blanchard et al, 2013; Yumani et al, 2013; DubbinkVerheij et al, 2017) These infections are often associated with significant mortality and morbidity and contribute to high healthcare costs (Payne et al, 2004). A direct link between neonatal sepsis caused by S. capitis and CVC implantation, has been questioned (Wang et al, 1999; Butin et al, 2019). Direct contamination of implanted CVCs by bacteria from the NICU environment, patients’ skin or microbial translocation from the gut, throat or nostrils of patients, and subsequently bacterial adherence and biofilm formation are considered the key initiating steps of CRBSI (Hitzenbichler et al, 2017)

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