Biofilm formation causes prolonged wound infections due to the dense biofilm structure, differential gene regulation to combat stress, and production of extracellular polymeric substances. ...Acinetobacter baumannii, Staphylococcus aureus, and Pseudomonas aeruginosa are three difficult-to-treat biofilm-forming bacteria frequently found in wound infections. This work describes a novel wound dressing in the form of an electrochemical scaffold (e-scaffold) that generates controlled, low concentrations of hypochlorous acid (HOCl) suitable for killing biofilm communities without substantially damaging host tissue. Production of HOCl near the e-scaffold surface was verified by measuring its concentration using needle-type microelectrodes. E-scaffolds producing 17, 10 and 7 mM HOCl completely eradicated S. aureus, A. baumannii, and P. aeruginosa biofilms after 3 hours, 2 hours, and 1 hour, respectively. Cytotoxicity and histopathological assessment showed no discernible harm to host tissues when e-scaffolds were applied to explant biofilms. The described strategy may provide a novel antibiotic-free strategy for treating persistent biofilm-associated infections, such as wound infections.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Hydrogen peroxide (H2O2) and hypochlorous acid (HOCl) are biocides used for cleaning and debriding chronic wound infections, which often harbor drug-resistant bacteria. Here, we evaluated the in ...vitro activity of H2O2 and HOCl against 27 isolates of eight bacterial species involved in wound infections. Minimum inhibitory concentrations (MICs) and minimum biofilm bactericidal concentrations (MBBCs) were measured. Compared to their respective MICs, MBBCs of isolates exposed to H2O2 were 16- to 1,024-fold higher, and those exposed to HOCl were 2- to 4-fold higher. We evaluated the selection of resistance after exposure of Staphylococcus aureus and Pseudomonas aeruginosa biofilms to 10 iterations of electrochemically generated HOCl or H2O2 delivered using electrochemical scaffolds (e-scaffolds), observing no decrease in antibiofilm effects with serial exposure to e-scaffold-generated H2O2 or HOCl. Twenty-four-hour exposure to H2O2-generating e-scaffolds consistently decreased the number of CFU of S. aureus and P. aeruginosa biofilms by ∼5.0 log10 and ∼4.78 log10 through 10 iterations of exposure, respectively. Four-hour exposure to HOCl-generating e-scaffolds consistently decreased the number of CFU of S. aureus biofilms by ∼4.9 log10, and 1-h exposure to HOCl-generating e-scaffolds consistently decreased the number of CFU of P. aeruginosa biofilms by ∼1.57 log10. These results suggest that HOCl has similar activity against planktonic and biofilm bacteria whereas the activity of H2O2 is less against biofilm than planktonic bacteria, and that repeat exposure to either biocide, generated electrochemically under the experimental conditions studied, does not lessen antibiofilm effects.
The antibiofilm activity of oritavancin in combination with rifampin, gentamicin, or linezolid was evaluated against 10 prosthetic joint infection (PJI)-related methicillin-resistant
(MRSA) isolates ...by time-kill assays. Oritavancin combined with rifampin demonstrated statistically significant bacterial reductions compared with those of either antimicrobial alone for all 10 isolates (
≤ 0.001), with synergy being observed for 80% of the isolates. Oritavancin and rifampin combination therapy may be an option for treating MRSA PJI.
The antibiofilm activity of a hypochlorous acid (HOCl)-producing electrochemical bandage (e-bandage) was assessed against 14 yeast isolates
. The evaluated e-bandage was polarized at +1.5 V
to allow ...continuous production of HOCl. Time-dependent decreases in the biofilm CFU counts were observed for all isolates with e-bandage treatment. The results suggest that the described HOCl-producing e-bandage could serve as a potential alternative to traditional antifungal wound biofilm treatments.
Abstract
Aims
As antimicrobial resistance is on the rise, treating chronic wound infections is becoming more complex. The presence of biofilms in wound beds contributes to this challenge. Here, the ...activity of a novel hypochlorous acid (HOCl) producing electrochemical bandage (e-bandage) against monospecies and dual-species bacterial biofilms formed by bacteria commonly found in wound infections was assessed.
Methods and results
The system was controlled by a wearable potentiostat powered by a 3V lithium-ion battery and maintaining a constant voltage of + 1.5V Ag/AgCl, allowing continuous generation of HOCl. A total of 19 monospecies and 10 dual-species bacterial biofilms grown on polycarbonate membranes placed on tryptic soy agar (TSA) plates were used as wound biofilm models, with HOCl producing e-bandages placed over the biofilms. Viable cell counts were quantified after e-bandages were continuously polarized for 2, 4, 6, and 12 hours. Time-dependent reductions in colony forming units (CFUs) were observed for all studied isolates. After 12 hours, average CFU reductions of 7.75 ± 1.37 and 7.74 ± 0.60 log10 CFU/cm2 were observed for monospecies and dual-species biofilms, respectively.
Conclusions
HOCl producing e-bandages reduce viable cell counts of in vitro monospecies and dual-species bacterial biofilms in a time-dependent manner in vitro. After 12 hours, >99.999% reduction in cell viability was observed for both monospecies and dual-species biofilms.
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BFBNIB, FZAB, GIS, IJS, KILJ, OILJ, SBCE, SBMB, UPUK
Oxidizing agents like hypochlorous acid (HOCl) have antimicrobial activity. We developed an integrated electrochemical scaffold, or e-scaffold, that delivers a continuous low dose of HOCl aimed at ...targeting microbial biofilms without exceeding concentrations toxic to humans as a prototype of a device being developed to treat wound infections in humans. In this work, we tested the device against 33 isolates of bacteria (including isolates with acquired antibiotic resistance) grown as
biofilms alongside 12 combinations of dual-species
biofilms. Biofilms were grown on the bottoms of 12-well plates for 24 h. An integrated e-scaffold was placed atop each biofilm and polarized at 1.5 V for 1, 2, or 4 h. HOCl was produced electrochemically by oxidizing chloride ions (Cl
) in solution to chlorine (Cl
); dissolved Cl
spontaneously dissociates in water to produce HOCl. The cumulative concentration of HOCl produced at the working electrode in each well was estimated to be 7.89, 13.46, and 29.50 mM after 1, 2, and 4 h of polarization, respectively. Four hours of polarization caused an average reduction of 6.13 log
CFU/cm
(±1.99 log
CFU/cm
) of viable cell counts of monospecies biofilms and 5.53 log
CFU/cm
(±2.31 log
CFU/cm
) for the 12 dual-species biofilms studied. The described integrated e-scaffold reduces viable bacterial cell counts in biofilms formed by an array of antibiotic-susceptible and -resistant bacteria alone and in combination.
Wound infections are caused by bacteria and/or fungi. The presence of fungal biofilms in wound beds presents a unique challenge, as fungal biofilms may be difficult to eradicate. The goal of this ...work was to assess the
antibiofilm activity of an H
O
-producing electrochemical bandage (e-bandage) against 15 yeast isolates representing commonly encountered species. Time-dependent decreases in viable biofilm CFU counts of all isolates tested were observed, resulting in no visible colonies with 48 h of exposure by plate culture. Fluorescence microscopic analysis showed extensive cell membrane damage of biofilm cells after e-bandage treatment. Reductions in intracellular ATP levels of yeast biofilm cells were recorded post e-bandage treatment. These results suggest that exposure to H
O
-producing e-bandages reduces
viable cell counts of yeast biofilms, making this a potential new topical treatment approach for fungal wound infections.
The activity of a hypochlorous acid‐producing electrochemical bandage (e‐bandage) in preventing methicillin‐resistant Staphylococcus aureus infection (MRSA) infection and removing biofilms formed by ...MRSA was assessed using a porcine explant biofilm model. e‐Bandages inhibited S. aureus infection (p = 0.029) after 12 h (h) of exposure and reduced 3‐day biofilm viable cell counts after 6, 12, and 24 h exposures (p = 0.029). Needle‐type microelectrodes were used to assess HOCl concentrations in explant tissue as a result of e‐bandage treatment; toxicity associated with e‐bandage treatment was evaluated. HOCl concentrations in infected and uninfected explant tissue varied between 30 and 80 µM, decreasing with increasing distance from the e‐bandage. Eukaryotic cell viability was reduced by an average of 71% and 65% in fresh and day 3‐old explants, respectively, when compared to explants exposed to nonpolarized e‐bandages. HOCl e‐bandages are a promising technology that can be further developed as an antibiotic‐free treatment for wound biofilm infections.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•Investigated mechanism of action of H2O2 producing e-bandage.•Counter electrode produces HOCl.•HOCl was shown to inhibit catalase enzyme.
Previously, an electrochemical bandage (e-bandage) that uses ...a three-electrode system to produce hydrogen peroxide (H2O2) electrochemically on its working electrode was developed as a potential strategy for treating biofilms; it showed activity in reducing biofilms in an agar biofilm model. Xanthan gum-based hydrogel, including NaCl, was used as the electrolyte. While H2O2 generated at the working electrode in the vicinity of a biofilm is a main mechanism of activity, the role of the counter electrode was not explored. The goal of this research was to characterize electrochemical reactions occurring on the counter electrode of the e–bandage. Counter electrode potential varied between 1.2 and 1.5 VAg/AgCl; ∼125 µM hypochlorous acid (HOCl) was generated within 24 h in the e-bandage system. When HOCl was not produced on the counter electrode (achieved by removing NaCl from the hydrogel), reduction of Acinetobacter baumannii BAA-1605 biofilm was 1.08 ± 0.38 log10 CFU/cm2 after 24 h treatment, whereas when HOCl was produced, reduction was 3.87 ± 1.44 log10 CFU/cm2. HOCl inhibited catalase activity, abrogating H2O2 decomposition. In addition to H2O2 generation, the previously described H2O2-generating e-bandage generates HOCl on the counter electrode, enhancing its biocidal activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The antibiofilm activity of a hydrogen peroxide-generating electrochemical scaffold (e-scaffold) was determined against mono- and trispecies biofilms of methicillin-resistant
, multidrug-resistant
, ...and
Significant time-dependent decreases were found in the overall CFU of biofilms of all three monospecies and the trispecies forms. Confocal laser scanning microscopy showed dramatic reductions in fluorescence intensities of biofilm matrix protein and polysaccharide components of e-scaffold-treated biofilms. The described e-scaffold has potential as a novel antibiotic-free strategy for treating wound biofilms.
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