A three-phase in-vitro system for studying Pseudomonas aeruginosa adhesion and biofilm formation upon hydrogel contact lenses

Claudia Rändler,Rutger Matthes,Andrew J Mcbain,Axel Kramer,Nils-Olaf Hübner,Rabea Sietmann,Bernd Giese,Thomas Kohlmann,Martin Fraunholz

doi:10.1186/1471-2180-10-282

Claudia Rändler, Rutger Matthes + Show 7 more

Open Access

https://doi.org/10.1186/1471-2180-10-282

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Abstract

BackgroundPseudomonas aeruginosa is commonly associated with contact lens (CL) -related eye infections, for which bacterial adhesion and biofilm formation upon hydrogel CLs is a specific risk factor. Whilst P. aeruginosa has been widely used as a model organism for initial biofilm formation on CLs, in-vitro models that closely reproduce in-vivo conditions have rarely been presented.ResultsIn the current investigation, a novel in-vitro biofilm model for studying the adherence of P. aeruginosa to hydrogel CLs was established. Nutritional and interfacial conditions similar to those in the eye of a CL wearer were created through the involvement of a solid:liquid and a solid:air interface, shear forces and a complex artificial tear fluid. Bioburdens varied depending on the CL material and biofilm maturation occurred after 72 h incubation. Whilst a range of biofilm morphologies were visualised including dispersed and adherent bacterial cells, aggregates and colonies embedded in extracellular polymer substances (EPS), EPS fibres, mushroom-like formations, and crystalline structures, a compact and heterogeneous biofilm morphology predominated on all CL materials.ConclusionsIn order to better understand the process of biofilm formation on CLs and to test the efficacy of CL care solutions, representative in-vitro biofilm models are required. Here, we present a three-phase biofilm model that simulates the environment in the eye of a CL wearer and thus generates biofilms which resemble those commonly observed in-situ.

Highlights

Pseudomonas aeruginosa is commonly associated with contact lens (CL) -related eye infections, for which bacterial adhesion and biofilm formation upon hydrogel contact lenses (CLs) is a specific risk factor
Pseudomonas aeruginosa biofilm growth on various contact lens materials To evaluate biofilm formation in the novel in-vitro biofilm model (Figure 1), the accumulation of viable bacterial cells over time was measured on four CLs using quantitative culturing (Figure 2)
Analysis of variance showed that biofilm growth was significantly affected primarily by the incubation time, and secondarily by the CL material

Summary

Introduction

Pseudomonas aeruginosa is commonly associated with contact lens (CL) -related eye infections, for which bacterial adhesion and biofilm formation upon hydrogel CLs is a specific risk factor. Whilst Gram-negative bacteria, P. aeruginosa, are commonly associated with the condition, within the last four years, two notable outbreaks of CL-associated infectious keratitis have occurred, which were caused by the normally uncommon agents, Fusarium (2006 in Singapore, Hong Kong and the USA) and Acanthamoeba (2007 in USA). These infections were associated with the use of the CL care solutions “ReNu® with MoistureLoc®” and “Complete® MoisturePlusTM”, respectively [4]. Biofilm formation on CLs is a complex process which may differ markedly between individuals

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