Biology subjects

Beyenal, H.

Publications and source records attributed to Beyenal, H..

5 recordsLinked to original sources

bioRxiv2024

Evaluation of Treatment of Methicillin-Resistant Staphylococcus aureus Biofilms with Intermittent Electrochemically-Generated H2O2 or HOCl

Chronic wound infections can be difficult to treat and may lead to impaired healing and worsened patient outcomes. Novel treatment strategies are needed. This study evaluated effects of intermittently produced H2O2 and HOCl, generated via an electrochemical bandage (e-bandage), against methicillin-resistant Staphylococcus aureus biofilms in an agar membrane biofilm model. By changing the working electrode potential, the e-bandage generated either HOCl (1.5 VAg/AgCl) or H2O2 (-0.6 VAg/AgCl). The degree of biocidal activity of intermittent treatment with HOCl and H2O2 correlated with HOCl treatment time; HOCl treatment durations of 0, 1.5, 3, 4.5, and 6 hours (with the rest of the 6 hour total treatment time devoted to H2O2 generation) resulted in mean biofilm reductions of 1.36{+/-}0.2, 2.22{+/-}0.16, 3.46{+/-}0.38, 4.63{+/-}0.74 and 7.66{+/-}0.5 log CFU/cm2, respectively vs. non-polarized controls, respectively. However, application of H2O2 immediately after HOCl treatment was detrimental to biofilm removal. For example, 3-hours HOCl treatment followed by 3-hours H2O2 resulted in a 1.90{+/-}0.84 log CFU/cm2 lower mean biofilm reduction than 3-hours HOCl treatment followed by 3-hours non-polarization. HOCl generated over 3-hours exhibited biocidal activity for at least 7.5-hours after e-bandage operation ceased; 3-hours of HOCl generation followed by 7.5-hours of non-polarization resulted in a biofilm cell reduction of 7.92{+/-}0.12 log CFU/cm2 vs. non polarized controls. Finally, intermittent treatment with HOCl (i.e., interspersed with periods of e-bandage non-polarization) for various intervals showed similar effects (approximately 6 log CFU/cm2 reduction vs. non-polarized control) to continuous treatment with HOCl for 3-hours, followed by 3-hours of non-polarization. These findings suggest that timing and sequencing of HOCl and H2O2 treatments are crucial for maximizing biofilm control.

bioengineering↗

bioRxiv2024

DUAL ACTION ELECTROCHEMICAL BANDAGE OPERATED by a PROGRAMMABLE MULTIMODAL WEARABLE POTENTIOSTAT

Electrochemical bandages (e-bandages) can be applied to biofilm-infected wounds to generate reactive oxygen species, such as hypochlorous acid (HOCl) or hydrogen peroxide (H2O2). The e-bandage-generated HOCl or H2O2 kills biofilms in vitro and in infected wounds on mice. The HOCl-generating e-bandage is more active against biofilms in vitro, although this distinction is less apparent in vivo. The H2O2-generating e-bandage, more than the HOCl-generating e-bandage, is associated with improved healing of infected wounds. A strategy in which H2O2 and HOCl are generated alternately--for dual action--was explored. The goal was to develop a programmable multimodal wearable potentiostat (PMWP) that could be programmed to generate HOCl or H2O2, as needed. An ultralow-power microcontroller unit managed operation of the PMWP. The system was operated with a 260-mAh capacity coin battery and weighed 4.6 grams, making it suitable for small animal experiments or human use. The overall cost of a single wearable potentiostat was $6.50 (USD). The device was verified using established electrochemical systems and functioned comparably to a commercial potentiostat. To determine antimicrobial effectiveness, PMWP-controlled e-bandages were tested against clinical isolates of four prevalent chronic wound bacterial pathogens, methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterococcus faecium, and one fungal pathogen of emerging concern, Candida auris. PMWP-controlled e-bandages exhibited broad-spectrum activity against biofilms of all study isolates tested when programmed to deliver HOCl followed by H2O2. These results show that the PMWP operates effectively and is suitable for animal testing.

bioengineering↗

bioRxiv2024

HOCl-producing Electrochemical Bandage is Active in Murine Polymicrobial Wound Infection

Wound infections, exacerbated by the prevalence of antibiotic-resistant bacterial pathogens, necessitate innovative antimicrobial approaches. Polymicrobial infections, often involving Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA), present formidable challenges due to biofilm formation and antibiotic resistance. Hypochlorous acid (HOCl), a potent antimicrobial agent produced naturally by the immune system, holds promise as an alternative therapy. An electrochemical bandage (e-bandage) that generates HOCl in situ was evaluated for treatment of murine wound biofilm infections containing both MRSA and P. aeruginosa with "difficult-to-treat" resistance. Previously, the HOCl-producing e-bandage was shown to reduce wound biofilms containing P. aeruginosa alone. Compared to non-polarized e-bandage (no HOCl production) and Tegaderm only controls, the polarized e-bandages reduced bacterial loads in wounds infected with MRSA plus P. aeruginosa (MRSA: vs Tegaderm only - 1.4 log10 CFU/g, p = 0.0015, vs. non-polarized - 1.1 log10 CFU/g, p = 0.026. P. aeruginosa: vs Tegaderm only - 1.6 log10 CFU/g, p = 0.0015, vs non-polarized - 1.6 log10 CFU/g, p = 0.0032), and MRSA alone (vs Tegaderm only - 1.3 log10 CFU/g, p = 0.0048, vs. non-polarized - 1.1 log10 CFU/g, p = 0.0048), without compromising wound healing or causing tissue toxicity. Addition of systemic antibiotics did not enhance the antimicrobial efficacy of e-bandages, highlighting their potential as standalone therapies. This study provides additional evidence for the HOCl-producing e-bandage as a novel antimicrobial strategy for managing wound infections, including in the context of antibiotic resistance and polymicrobial infections.

microbiology↗

bioRxiv2023

HOCl-producing Electrochemical Bandages for Treating Pseudomonas aeruginosa-Infected Murine Wounds

A novel electrochemical bandage (e-bandage) delivering low-level hypochlorous acid (HOCl) was evaluated against Pseudomonas aeruginosa murine wound biofilms. 5 mm skin wounds were created on the dorsum of Swiss-Webster mice and infected with 106 colony forming units (CFU) of P. aeruginosa. Biofilms were formed over two days, after which e-bandages were placed on the wound beds and covered with Tegaderm. Mice were administered Tegaderm-only (control), non-polarized e-bandage (no HOCl production), or polarized e-bandage (using an HOCl-producing potentiostat), with or without concurrently administered systemic amikacin. Purulence and wound areas were measured before and after treatment. After 48 hours, animals were sacrificed, and wounds were harvested for bacterial quantification. Forty-eight hours of polarized e-bandage treatment resulted in mean biofilm reductions of 1.4 log10 CFUs/g (9.0 vs 7.6 log10; p = 0.0107) vs non-polarized controls, and 2.2 log10 CFU/g (9.8 vs 7.6 log10; p = 0.004) vs Tegaderm only controls. Systemic amikacin improved CFU reduction in Tegaderm-only (p = 0.0045) and non-polarized control groups (p = 0.0312), but not in the polarized group (p = 0.3876). Compared to the Tegaderm only group, there was more purulence reduction in the polarized group (p = 0.009), but not in the non-polarized group (p = 0.064). Wound closure was not impeded or improved by either polarized or non-polarized e-bandage treatment. Concurrent amikacin did not impact wound closure or purulence. In conclusion, an HOCl-producing e-bandage reduced P. aeruginosa in wound biofilms with no impairment in wound healing, representing a promising antibiotic-free approach for addressing wound infections.

microbiology↗

bioRxiv2023

Dual Roles of the Conditional Exosomes Derived from Pseudomonas aeruginosa Biofilms: Promoting and Inhibiting Bacterial Biofilm Growth

Antibiotic-resistant biofilm infections have emerged as public health concerns because of their enhanced tolerance of high-dose antibiotic treatments. The biofilm life cycle involves multiple developmental stages, which are tightly regulated by active cell-cell communication via specific extracellular signal messengers such as exosomes. This study was aimed at exploring the roles of Pseudomonas aeruginosa exosomes secreted at different developmental stages in controlling biofilm growth. Our results show that exosomes secreted by P. aeruginosa biofilms during their exponential growth phase (G-Exo) enhance biofilm growth. In contrast, exosomes secreted by P. aeruginosa biofilms during their death/survival phase (D-Exo) can effectively inhibit/eliminate P. aeruginosa PAO1 biofilms up to 4.8-log10 CFU/cm2. The inhibition effectiveness of D-Exo against P. aeruginosa biofilms grown for 96 hours improved further in the presence of 10-50 M Fe3+ ions. Proteomic analysis suggests the inhibition involves an iron-dependent ferroptosis mechanism. This study is the first to report the functional role of bacterial exosomes in bacterial growth, which depends on the developmental stage of the parent bacteria. The finding of D-Exo-activated ferroptosis-based bacterial death may have significant implications for preventing antibiotic resistance in biofilms. Significance statementAntibiotic-resistant bacterial infections caused 1.27 million deaths in 2019 [1], and this number is projected to increase to 10 million deaths annually worldwide by 2050 [2]. Of these infections, up to 80% are caused by biofilm-associated infections [3, 4], which pose a significant challenge to human health. The treatment of biofilm infections remains a formidable problem because of the limited effectiveness of the currently available antibiotics against drug-resistant biofilms [5, 6]. The development of new therapeutic approaches that can effectively combat biofilm infections is required. This study represents a promising solution to antibiotic-resistant biofilm infections. The successful use of exosomes against biofilms opens new possibilities for combating challenging antibiotic-resistant biofilm infections.

microbiology↗