Agar-entrapped bacteria as an in vitro model of biofilms and their susceptibility to antibiotics

Jouenne, Thierry; Tresse, Odile; Junter, Guy-Alain

doi:10.1111/j.1574-6968.1994.tb06894.x

Cited by 53 publications

(14 citation statements)

References 18 publications

(26 reference statements)

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“…and in artificial biofilm alginate gel beads (---, low cell density; --, high cell density) exposed to 2·5 mg l -1 chlorine bleach (a); 25 mg l -1 glutaraldehyde (b); 0·77 mg l -1 isothiazolone (c); and 10 mg l -1 ADBAC (d). Shown are data for 6·0 mm diameter gel beads that were initially loaded with bacteria at densities between 4·2 × 10 7 and 6·9 × 10 7 cfu ml -1 (low) or between 4·5 × 10 9 and 6·4 × 10 9 cfu ml -1 (high) Chlorine 2·0 19 Glutaraldehyde 0·14 7 Isothiazolone 1·1 29 ADBAC 0·13 1·9 - -----------------------------------------------------and Gilbert 1993; Jouenne et al 1994;Chen and Stewart 1996;Xu et al 1996) and is consistent with the nearly universally observed reduced susceptibility of biofilms to disinfection. At least with regard to antimicrobial challenge, the alginate gel bead artificial biofilm system does appear to capture some of the features of real biofilms.…”

Section: Discussionmentioning

confidence: 99%

Analysis of biocide transport limitation in an artificial biofilm system

Stewart

Grab²,

Diemer³

1998

Journal of Applied Microbiology

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P .S . S T EW AR T , L . G R AB AN D J.A. D IE ME R . 1998. An alginate gel bead artificial biofilm system was used to assay biofilm susceptibility to four biocides and to analyse the extent to which each agent penetrated the biofilm. Chlorine, glutaraldehyde, an isothiazolone, and a quaternary ammonium compound were tested on alginate-entrapped Enterobacter aerogenes in gel beads ranging from 1·8 to 6 mm in diameter. Gel-entrapped bacteria were less susceptible to all four antimicrobial agents than were planktonic micro-organisms. The degree of kill measured in artificial biofilm gel beads depended on the size of the gel bead and the cell density at which it was loaded. Disinfection efficacy decreased as gel bead radius or cell density increased. The manifest dependence of biofilm disinfection efficacy on the physical properties of the artificial biofilm (radius and cell density) suggests the impingement of transport limitation of biocide transport into the biofilm. A previously developed theory of biocide reaction and diffusion in biofilm was tested by calculating an appropriate Thiele modulus. In accordance with the theory, the efficacy of all four biocides decreased, albeit noisily, as the Thiele modulus exceeded 1. This result demonstrates that transport limitation can impact antimicrobial performance against biofilms not only of oxidizing biocides but also of nonoxidizing agents.

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Section: Discussionmentioning

confidence: 99%

Analysis of biocide transport limitation in an artificial biofilm system

Stewart

Grab²,

Diemer³

1998

Journal of Applied Microbiology

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“…These variable characteristics have created the need for reproducible culture techniques to investigate the properties of biofilms. Biofilms can be generated in vitro in many ways (McCoy et al 1981;Prosser et al 1987;Gilbert et al 1989;Wimpenny et al 1989;Jouenne et al 1994;Hodgson et al 1995). However, with these Correspondence to: Prof. Michael R.W.…”

Section: Introductionmentioning

confidence: 99%

Generation of a reproducible nutrient‐depleted biofilm of Escherichia coli and Burkholderia cepacia

Bühler

Ballestero

Desai

et al. 1998

Journal of Applied Microbiology

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An in vitro method of growing bacteria as a defined nutrient‐depleted biofilm is proposed. The medium was defined nutritionally in terms of the quantitative composition and by the total amount of nutrient required to achieve a defined population size. Escherichia coli and Burkholderia cepacia were incubated on a filter support placed on a defined volume of solid medium. The change of biomass of the biofilm population was compared with the change in a planktonic culture. The size of the population in stationary phase was proportional to the concentration of limiting substrate up to 40 μmol cm−2 glucose for E. coli and up to 2·7 × 10−9 mol cm−2 iron for B. cepacia. Escherichia coli growing exponentially had a growth rate of μ = 0·30 h−1 in a biofilm and μ = 0·96 h−1 in planktonic culture. The growth rate, μ, for exponentially growing B. cepacia in a biofilm was 1·12 h−1 and in planktonic culture 0·78 h−1. This method allows the limitation of the size of a biofilm population to a chosen value.

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“…It was hypothesised that the matrix did this by either physically influencing the rate of transport of the antimicrobial agent or by deactivating it on its passage through the matrix. Recent in vitro studies have disproven this hypothesis for the majority of antimicrobials by documenting unimpaired antimicrobial penetration of the biofilm [12][13][14][15][16][17][18] . Three exceptions must be noted however involving aminoglycosides, betalactams and some glycopeptide antibiotics.…”

Section: Antibiotic Sensitivitymentioning

confidence: 99%