Fleming, Derek

ABSTRACTIntraluminal infection of central venous catheters, used for long‐term treatment, can result in central line‐associated bloodstream infection (CLABSI). These infections can be challenging to prevent and treat due to formation of biofilms within catheter lumens, which shield bacteria from the human immune response and conventional antimicrobial therapies. Preventing bacterial colonization of catheter hubs is a strategy to prevent CLABSI. To address this, we developed a nonantibiotic, animal‐ready electrochemical catheter hub (e‐catheter hub), operated by a wearable, battery‐powered micropotentiostat (MP), that internally generates tunable hypochlorous acid (HOCl) for preventing intraluminal infection. The design evaluated three different electrode materials—titanium, platinum, and gold—for HOCl generation and biocidal activity, using working and counter electrodes of the same materials and a silver/silver chloride‐plated wire as a quasi‐reference electrode. e‐catheter hubs operated by MPs at 1.5 VAg/AgCl for 3 h generated HOCl, reducing Acinetobacter baumannii ATCC‐17978 below the detection limit (average reduction of 4.40 ± 0.05 log10 CFU/mL). The efficacy of e‐catheter hubs operated by MPs in generating HOCl and achieving biocidal activity is comparable to that of a commercial potentiostat. This study represents the first step in developing a localized, nonantibiotic strategy to mitigate CLABSI risk.

ABSTRACT Although lung transplant recipients who develop Ureaplasma- associated hyperammonemia syndrome are treated with Ureaplasma -targeted antibiotics, optimal therapy is incompletely defined, and typically not based on real-time antimicrobial susceptibility testing results. This study compared levofloxacin, azithromycin, and doxycycline prevention and treatment of Ureaplasma urealyticum (UU) and Ureaplasma parvum (UP) infections in an immunosuppressed murine lung infection model. For prophylaxis, mice received antibiotics before infection with UP-FS (susceptible to all study antibiotics), UP-AzmR (azithromycin-resistant), UP-LevR (levofloxacin-resistant), or UU-DoxR (doxycycline-resistant), with lung bacterial loads (color changing units [CCUs]) measured 18 hours following infection. For UP-FS, doxycycline was most active (Δ4.84 log 10 CCU/g; P = 0.0006), followed by levofloxacin (Δ2.45 log 10 CCU/g; P = 0.018), with azithromycin yielding a nonsignificant CCU reduction. Doxycycline (Δ1.9 log 10 CCU/g; P = 0.0025) and levofloxacin (Δ1.3 log 10 CCU/g; P = 0.004) showed activity against UP-AzmR. Only doxycycline showed activity against UP-LevR (Δ2.28 log 10 CCU/g; P = 0.0002), and only azithromycin showed activity against UU-DoxR (Δ0.67 log 10 CCU/g; P = 0.0175). For treatment, antibiotics were administered 24 hours following infection; doxycycline significantly reduced bacterial loads of all study isolates, except UU-DoxR. In addition, azithromycin was active against UP-LevR (Δ1.21 log 10 CCU/g reduction; P = 0.0003). In summary, except for doxycycline-resistant UU, doxycycline was active in preventing and treating Ureaplasma lung infection in immunosuppressed mice.

ABSTRACT Ureaplasma species can cause systemic infections in immunocompromised hosts, including lung transplant recipients. Here, we investigated the impact of prior exposure to Ureaplasma urealyticum on the risk of U. urealyticum and Ureaplasma parvum infection in mice subjected to an immunosuppression regimen similar to that administered to solid organ transplant recipients. Mice were immunized with three intramuscular injections of U. urealyticum , with control mice injected with adjuvant only. Following immunization, mice received tacrolimus, mycophenolate mofetil, and methylprednisolone, and then were challenged with U. urealyticum or U. parvum intraperitoneally and intratracheally over 6 days. Relative U. urealyticum antibody levels in plasma were assessed over time, and lungs were harvested at sacrifice for bacterial load quantification, assessed using a color-changing unit assay. U. urealyticum antibody levels were higher in immunized compared with control animals ( P < 0.0001), even when animals were immunosuppressed. U. urealyticum and U. parvum lung burden was reduced in immunized compared with control mice (~6 log 10 reduction for U. urealyticum and <1 log 10 reduction for U. parvum ; P = 0.008 and 0.046, respectively). In summary, this study shows that prior exposure to live U. urealyticum provides some protection against infection with U. urealyticum . IMPORTANCE Ureaplasma -induced hyperammonemia syndrome is a rare but potentially deadly complication of solid organ transplantation, especially lung transplantation. The pathophysiology of this relatively recently recognized condition is poorly understood, and it is unclear what factors may influence patient susceptibility. This study investigates the possible protective effects of prior exposure to Ureaplasma urealyticum in a mouse model subjected to an immunosuppression regimen similar to that given to lung transplant recipients. The findings show that prior exposure could provide protection against Ureaplasma lung infection.

ABSTRACT 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 challenges due to biofilm formation and antibiotic resistance. Hypochlorous acid (HOCl), a potent antimicrobial agent, holds promise as an alternative therapy. An electrochemical bandage (e-bandage) that generates HOCl in situ via precise polarization controlled by a miniaturized potentiostat was evaluated for the treatment of murine wound biofilm infections containing both P. aeruginosa with “difficult-to-treat” resistance and MRSA. Previously, HOCl-producing e-bandage was shown to reduce murine wound biofilms containing P. aeruginosa alone. Here, in 5-mm excisional skin wounds containing 48-h biofilms comprising MRSA and P. aeruginosa combined, polarized e-bandage treatment reduced MRSA by 1.1 log 10 CFU/g ( P = 0.026) vs non-polarized e-bandage treatment (no HOCl production), and 1.4 log 10 CFU/g (0.0015) vs Tegaderm only controls; P. aeruginosa was similarly reduced by 1.6 log 10 CFU/g ( P = 0.0032) and 1.6 log 10 CFU/g ( P = 0.0015), respectively. For wounds infected with MRSA alone, polarized e-bandage treatment reduced bacterial load by 1.1 log 10 CFU/g ( P = 0.0048) and 1.3 log 10 CFU/g ( P = 0.0048) compared with non-polarized e-bandage and Tegaderm only, respectively. The e-bandage treatment did not negatively impact wound healing or cause tissue toxicity. The addition of systemic antibiotics did not enhance the antimicrobial efficacy of e-bandages. 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. IMPORTANCE New approaches are needed to combat the rise of antimicrobial-resistant infections. The HOCl-producing electrochemical bandage (e-bandage) leverages in situ generation of HOCl, a natural biocide, for broad-spectrum killing of wound pathogens. Unlike traditional therapies that may exhibit limited activity against biofilms and antimicrobial-resistant organisms, the e-bandage offers a potent, standalone solution that does not contribute to further resistance or require adjunctive antibiotic therapy. Here, we show the ability of the e-bandage to address polymicrobial infection by antimicrobial resistant clinical isolates of Staphylococcus aureus and Pseudomonas aeruginosa , two commonly isolated, co-infecting wound pathogens. Effectiveness of the HOCl-producing e-bandage in reducing pathogen load while minimizing tissue toxicity and avoiding the need for systemic antibiotics underscores its potential as a tool in managing complex wound infections.

ABSTRACT 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 the effects of intermittently produced hydrogen peroxide (H 2 O 2 ) and hypochlorous acid (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 V Ag/AgCl ) or H 2 O 2 (−0.6 V Ag/AgCl ). The degree of biocidal activity of intermittent treatment with HOCl and H 2 O 2 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 H 2 O 2 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/cm 2 , respectively, vs. non-polarized controls, respectively. However, application of H 2 O 2 immediately after HOCl treatment was detrimental to biofilm removal. For example, 3 hours HOCl treatment followed by 3 hours H 2 O 2 resulted in a 1.90 ± 0.84 log CFU/cm 2 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/cm 2 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/cm 2 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 H 2 O 2 treatments are crucial for maximizing biofilm control when using an e-bandage strategy.

ABSTRACT The growing threat of antibiotic-resistant bacterial pathogens necessitates the development of alternative antimicrobial approaches. This is particularly true for chronic wound infections, which commonly harbor biofilm-dwelling bacteria. A novel electrochemical bandage (e-bandage) delivering low-levels of hypochlorous acid (HOCl) was evaluated against Pseudomonas aeruginosa murine wound biofilms. 5 mm skin wounds were created on the dorsum of mice and infected with 10 6 colony-forming units (CFU) of P. aeruginosa . Biofilms were formed over 2 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 systemic amikacin. Purulence and wound areas were measured before and after treatment. After 48 hours, wounds were harvested for bacterial quantification. Forty-eight hours of polarized e-bandage treatment resulted in mean biofilm reductions of 1.4 log 10 CFUs/g ( P = 0.0107) vs non-polarized controls and 2.2 log 10 CFU/g ( P = 0.004) vs Tegaderm-only controls. 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 less purulence in the polarized group ( P = 0.009). Wound closure was neither impeded nor 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 infection.

ABSTRACT The ninth American Society for Microbiology Conference on Biofilms was convened in-person on 13–17 November 2022 in Charlotte, NC. As the first of these conferences since prior to the start of the COVID-19 pandemic, the energy among the participants of the conference was clear, and the meeting was a tremendous success. The mixture of >330 oral and poster presentations resoundingly embodied the vitality of biofilm research across a wide range of topics and multiple scientific disciplines. Special activities, including a pre-conference symposium for early career researchers, further enhanced the attendee experience. As a general theme, the conference was deliberately structured to provide high levels of participation and engagement among early career scientists.

AbstractBiofilms formed by antibiotic‐resistant bacteria in wound beds challenge the treatment of wound infections. In this work, the activity of a novel electrochemical bandage (e‐bandage) composed of carbon fabric and controlled by a wearable potentiostat, designed to continuously deliver low amounts of hydrogen peroxide (H2O2), is evaluated against methicillin‐resistant Staphylococcus aureus (MRSA), multidrug‐resistant Pseudomonas aeruginosa (MDR‐PA) and mixed‐species (MRSA and MDR‐PA) wound infections. Wounds created on Swiss Webster mice are infected with the above‐named bacteria and biofilms allow to establish in wound beds for 3 days. e‐Bandages, which electrochemically reduce dissolved oxygen to H2O2 when polarized at −0.6 VAg/AgCl, are placed atop infected wound beds and polarized continuously for 48 h. Polarized e‐bandage treatment results in significant reductions (p <0.001) of both monospecies and mixed‐species wound infections. After e‐bandage treatment, electron microscopy shows degradation of bacterial cells, and histopathology shows no obvious alterations to the inflammatory host response. Blood biochemistries show no abnormalities. Taken all together, results of this work suggest that the described H2O2‐producing e‐bandage can reduce in vivo MRSA, MDR‐PA, and mixed‐species wound biofilms, and should be further developed as a potential antibiotic‐free strategy for treatment of wound infections.

Ureaplasma -associated hyperammonemia syndrome occurs in 4% of lung transplant recipients and has historically been almost universally fatal. While Ureaplasma -targeted antibiotics have been shown to be protective, the possibility of underlying resistance and resistance selection render non-antibiotic interventions an interesting approach.

Ureaplasma -induced hyperammonemia is a deadly complication affecting around 4% of lung transplant recipients and, to a lesser extent, other solid organ transplant patients. Understanding the underlying mechanisms will inform patient management, potentially decreasing mortality and morbidity. Here, it is shown that uremia is a plausible contributing factor to the pathophysiology of the condition.