The role of flow in bacterial biofilm morphology and wetting properties

Recupido, Federica; Toscano, Giuseppe; Tatè, Rosarita; Petala, Maria; Caserta, Sergio; Karapantsios, Thodoris D.; Guido, Stefano

doi:10.1016/j.colsurfb.2020.111047

Cited by 23 publications

(32 citation statements)

References 43 publications

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“…Further experiments are necessary to extrapolate the behavior of bio lms on silicon catheters compared to glass ow cells as observed here. Bio lms formed in stagnant or stationary conditions are porous and develop mostly in height whereas those formed under continuous ow or with regular shaking develop thinner layers with clumped structures and patterns (18). Consequently, different morphologies have characteristic outcomes which should be considered as part of a comprehensive treatment strategy.…”

Section: Discussionmentioning

confidence: 99%

Biofilm prevention potential of 0.02% polyhexanide irrigation solution in urethral catheters under practice-like in vitro conditions

Brill

Hambach

Utpatel

et al. 2020

Preprint

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Background Long-term use of indwelling urethral catheters is associated with high risk of urinary tract infection (UTI) and blockage. Microbial biofilms are a common cause of catheter blockage, reduce their lifetime and significantly increase morbidity of UTIs. A 0.02% polyhexanide irrigation solution developed for routine mechanical rinsing shows potential for bacterial decolonization of suprapubic and indwelling urethral catheters and has the potential to reduce or prevent biofilm formation. Methods Using a practice-like in vitro assay and standard silicon catheters, artificially contaminated with clinically relevant bacteria, assays were carried out to evaluate the biofilm reduction and prevention potential of polyhexanide vs. no intervention (standard approach) and irrigation with saline solution (NaCl 0.9%). The biofilm mass was measured by crystal violet staining and fluorescence microscopy. Results Irrigation with a 0.02% polyhexanide solution reduced the biofilm mass by approx. 85% vs. non-treated catheters. Standard 0.9% saline solution was able to reduce the biofilm mass by approx. 50%. Fluorescence microscopy showed that polyhexanide is able to destroy bacteria in the biofilm, albeit only those cells on the upper layers. Conclusions The polyhexanide and standard saline solutions are able to reduce bacterial biofilm from urinary catheters, showing a combination of mechanical and antibacterial effects. The data supports a prevention strategy to avoid the formation of a thick biofilm, which is characteristically difficult to be efficiently removed. Further research is required to evaluate the long-term tolerability and efficacy of polyhexanide in clinical practice.

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Section: Discussionmentioning

confidence: 99%

Biofilm prevention potential of 0.02% polyhexanide irrigation solution in urethral catheters under practice-like in vitro conditions

Brill

Hambach

Utpatel

et al. 2020

Preprint

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“…The antimicrobial properties of TL were then investigated for biofilms cultivated under in-flow conditions, following an already validated approach [ 35 ]. Briefly, a continuous experimental set up made of a commercial microfluidic chamber (17 mm × 1 mm × 0.1 mm, Ibidi Cell in Focus, μ-Slide VI 0.1, Ibidi GmbH) and other auxiliary units, was selected.…”

Section: Methodsmentioning

confidence: 99%

“…For the selected operative condition, Reynolds number of the order of 10 −3 , corresponding to the laminar regime, typical of the microfluidic conditions. Detailed analysis of the role of flow intensity on transport phenomena in biofilm growth was discussed in Recupido et al [ 35 ].…”

Section: Methodsmentioning

confidence: 99%

“…Surface parameters, such as the surface covered by the biofilm over the total acquired area (%), maximum thickness (μm), and dimensionless roughness coefficient, Ra (-) were also obtained by processing red-channel-stack-images from TRITC ConA staining in the red channel under different growth conditions. Ra was evaluated according to Equation (5), as reported by Heydorn et al, and Recupido et al [ 35 , 37 ].

where

is the i -th individual thickness measurement (μm),

is the mean thickness (μm) and

is the number of thickness measurements.…”

Section: Methodsmentioning

confidence: 99%

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Antibiofilm Properties of Temporin-L on Pseudomonas fluorescens in Static and In-Flow Conditions

Somma

Recupido

Cirillo

et al. 2020

IJMS

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Biofilms consist of a complex microbial community adhering to biotic or abiotic surfaces and enclosed within a protein/polysaccharide self-produced matrix. The formation of this structure represents the most important adaptive mechanism that leads to antibacterial resistance, and therefore, closely connected to pathogenicity. Antimicrobial peptides (AMPs) could represent attractive candidates for the design of new antibiotics because of their specific characteristics. AMPs show a broad activity spectrum, a relative selectivity towards their targets (microbial membranes), the ability to act on both proliferative and quiescent cells, a rapid mechanism of action, and above all, a low propensity for developing resistance. This article investigates the effect at subMIC concentrations of Temporin-L (TL) on biofilm formation in Pseudomonas fluorescens (P. fluorescens) both in static and dynamic conditions, showing that TL displays antibiofilm properties. Biofilm formation in static conditions was analyzed by the Crystal Violet assay. Investigation of biofilms in dynamic conditions was performed in a commercial microfluidic device consisting of a microflow chamber to simulate real flow conditions in the human body. Biofilm morphology was examined using Confocal Laser Scanning Microscopy and quantified via image analysis. The investigation of TL effects on P. fluorescens showed that when subMIC concentrations of this peptide were added during bacterial growth, TL exerted antibiofilm activity, impairing biofilm formation both in static and dynamic conditions. Moreover, TL also affects mature biofilm as confocal microscopy analyses showed that a large portion of preformed biofilm architecture was clearly perturbed by the peptide addition with a significative decrease of all the biofilm surface properties and the overall biomass. Finally, in these conditions, TL did not affect bacterial cells as the live/dead cell ratio remained unchanged without any increase in damaged cells, confirming an actual antibiofilm activity of the peptide.

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“…The applied monitoring provides an approximated thickness, assuming a flat and homogeneous structure of the biofilm over the plate surface. Flow profile, temperature, and nutrient load can, however, affect the growth and the distribution of the biofilm [47]. In addition, it has been seen in pure-culture biofilm that temperature can cause a regulation of EPS production inducing morphological changes of the biofilm [15].…”

Section: Potential Applications In Future Researchmentioning

confidence: 99%

Assessment of the Impact of Temperature on Biofilm Composition with a Laboratory Heat Exchanger Module

et al. 2021

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Temperature change over the length of heat exchangers might be an important factor affecting biofouling. This research aimed at assessing the impact of temperature on biofilm accumulation and composition with respect to bacterial community and extracellular polymeric substances. Two identical laboratory-scale plate heat exchanger modules were developed and tested. Tap water supplemented with nutrients was fed to the two modules to enhance biofilm formation. One “reference” module was kept at 20.0 ± 1.4 °C and one “heated” module was operated with a counter-flow hot water stream resulting in a bulk water gradient from 20 to 27 °C. Biofilms were grown during 40 days, sampled, and characterized using 16S rRNA gene amplicon sequencing, EPS extraction, FTIR, protein and polysaccharide quantifications. The experiments were performed in consecutive triplicate. Monitoring of heat transfer resistance in the heated module displayed a replicable biofilm growth profile. The module was shown suitable to study the impact of temperature on biofouling formation. Biofilm analyses revealed: (i) comparable amounts of biofilms and EPS yield in the reference and heated modules, (ii) a significantly different protein to polysaccharide ratio in the EPS of the reference (5.4 ± 1.0%) and heated modules (7.8 ± 2.1%), caused by a relatively lower extracellular sugar production at elevated temperatures, and (iii) a strong shift in bacterial community composition with increasing temperature. The outcomes of the study, therefore, suggest that heat induces a change in biofilm bacterial community members and EPS composition, which should be taken into consideration when investigating heat exchanger biofouling and cleaning strategies. Research potential and optimization of the heat exchanger modules are discussed.

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The role of flow in bacterial biofilm morphology and wetting properties

Cited by 23 publications

References 43 publications

Biofilm prevention potential of 0.02% polyhexanide irrigation solution in urethral catheters under practice-like in vitro conditions

Biofilm prevention potential of 0.02% polyhexanide irrigation solution in urethral catheters under practice-like in vitro conditions

Antibiofilm Properties of Temporin-L on Pseudomonas fluorescens in Static and In-Flow Conditions

Assessment of the Impact of Temperature on Biofilm Composition with a Laboratory Heat Exchanger Module

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