Next science wound gel technology, a novel agent that inhibits biofilm development by gram-positive and gram-negative wound pathogens

A Diagnostic-Driven Prospective Clinical Study Evaluating the Combination of an Antibiofilm Agent and Negative Pressure Wound Therapy

BACKGROUND

Each year, millions of Americans develop truncal pressure ulcers (PUs) which can persist for months, years, or until the end of life. Despite the negative impact on quality of life and escalating costs associated with PUs, there is sparse evidence supporting validated and efficacious treatment options. As a result, treatment is based on opinion and extrapolation from other wound etiologies. The ideal reconstructive plan maximizes the patient's nutritional status, incorporates the basic tenets of wound bed preparation (debridement, offloading, proper moisture balance, reduction of bacterial burden), and employs diagnostics to guide therapeutic intervention. The use of combination therapies can potentially overcome several of the barriers to wound healing. Negative pressure wound therapy (NPWT), a commonly used modality in the management of PUs, facilitates healing by stimulating the formation of granulation tissue and promoting wound contraction; however, NPWT alone is not always effective. Clinical studies examining microbial bioburden in PUs determined that most ulcers contain bacteria at levels that impede wound healing (>104 CFU/g).

OBJECTIVE

Thus, we hypothesized that adding an anti-microbial agent to decrease both planktonic and biofilm bacteria in the wound would increase the efficacy of NPWT.

METHOD

In this prospective study, twenty patients with recalcitrant PUs that previously failed NPWT were treated with a biofilm-disrupting agent (Blast-X, Next Science, Jacksonville, FL, USA) in combination with NPWT. Fluorescence imaging was used to follow bacterial burden and guide therapy.

RESULTS

In total, 45% of the PUs reduced in size over the course of the four-week study, with a resolution of bacterial fluorescence in the NPWT dressing and wound bed seen in an average of three weeks.

CONCLUSION

The combination of an antibiofilm agent and NPWT reduced bacterial levels and improved wound healing in recalcitrant PUs.

Efficacy of biofilm disrupters against Candida auris and other Candida species in monomicrobial and polymicrobial biofilms

Candida species are now considered global threats by the CDC and WHO. Candida auris specifically is on the critical pathogen threat list along with Candida albicans. In addition, it is not uncommon to find Candida spp. in a mixed culture with bacterial organisms, especially Staphylococcus aureus producing polymicrobial infections. To eradicate these organisms from the environment and from patient surfaces, surface agents such as chlorhexidine (CHD) and Puracyn are used. Biofilm disrupters (BDs) are novel agents with a broad spectrum of antimicrobial activity and have been used in the management of chronic wounds and to sterilise environmental surfaces for the past several years. The goal of this study was to evaluate BDs (BlastX, Torrent, NSSD) and CHD against Candida spp. and S. aureus using zone of inhibition assays, biofilm and time-kill assays. All BDs and CHD inhibited C. auris growth effectively in a concentration-dependent manner. Additionally, CHD and the BDs showed excellent antimicrobial activity within polymicrobial biofilms. A comparative analysis of the BDs and CHD against C. auris and C. albicans using biofilm kill-curves showed at least 99.999% killing. All three BDs and CHD have excellent activity against different Candida species, including C. auris. However, one isolate of C. auris in a polymicrobial biofilm assay showed resistance/tolerance to CHD, but not to the BDs. The fungicidal activity of these novel agents will be valuable in eradicating surface colonisation of Candida spp, especially C. auris from colonised environmental surfaces and from wounds in colonised patients.

Carbon Dots' Potential in Wound Healing: Inducing M2 Macrophage Polarization and Demonstrating Antibacterial Properties for Accelerated Recovery

Bacterial infections and persistent inflammation can impede the intrinsic healing process of wounds. To combat this issue, researchers have delved into the potential use of carbon dots (CDs) in the regulation of inflammation and counteract infections. These CDs were synthesized using a microwave-assisted hydrothermal process and have demonstrated outstanding antibacterial and antibiofilm properties against Gram-positive and Gram-negative bacteria. Additionally, CDs displayed biocompatibility at therapeutic concentrations and the ability to specifically target mitochondria. CD treatment effectively nullified lipopolysaccharide-triggered reactive oxygen species production by macrophages, while simultaneously promoting macrophage polarization toward an anti-inflammatory phenotype (M2), leading to a reduction in inflammation and an acceleration in wound healing. In vitro scratch assays also revealed that CDs facilitated the tissue-repairing process by stimulating epithelial cell migration during reepithelialization. In vivo studies using CDs topically applied to lipopolysaccharide (LPS)-stimulated wounds in C57/BL6 mice demonstrated significant improvements in wound healing due to enhanced fibroblast proliferation, angiogenesis, and collagen deposition. Crucially, histological investigations showed no indications of systemic toxicity in vital organs. Collectively, the application of CDs has shown immense potential in speeding up the wound-healing process by regulating inflammation, preventing bacterial infections, and promoting tissue repair. These results suggest that further clinical translation of CDs should be considered.

Superficial Surgical Site Infections in Primary Total Joint Arthroplasty: A Retrospective Analysis of Topical Anti-Biofilm Therapy

Introduction Surgical site infections (SSI) following orthopedic procedures can cause significant morbidity and mortality, particularly in total joint arthroplasty. Biofilm formation in surgical wounds has made it difficult to prevent and treat these infections. SURGX® Antimicrobial Wound Gel (Next Science, Jacksonville, Florida, USA) was developed to disrupt biofilm formation but has not been evaluated in prophylactic use in total joint arthroplasty to prevent superficial SSI. Methods A retrospective chart review was performed at a single institution comparing the rate of SSI in patients undergoing primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). SSI data were collected from patients with standard postoperative dressings (Group A: Control) and patients with SURGX® applied as part of a standardized dressing following THA/TKA (Group B: Study). Rates of SSI were compared.  Results SURGX® was administered to 120 patients, including 91 TKAs and 29 THAs. The overall infection rate in this cohort was 2.5%. No superficial site infections developed. The control group constituted 566 patients, with 386 TKAs and 180 THAs. The infection rate was 1.24%, which included one superficial infection. Binary logistic regression did not show different odds of developing infections with the use of SURGX® (OR = 2.23, 95% CI: 0.54-9.13, p = 0.27). Conclusion In our small retrospective study, Next Science SURGX® Antimicrobial Wound Gel did not demonstrate a statistically significant difference in the rate of superficial SSI in total joint arthroplasty; however, Group B did not have any superficial SSI.

Anti-Biofilm Efficacy of Commonly Used Wound Care Products in In Vitro Settings

Considering the prevalence and pathogenicity of biofilms in wounds, this study was designed to evaluate the anti-biofilm capabilities of eight commercially available wound care products using established in vitro assays for biofilms. The products evaluated included dressings with multiple delivery formats for ionic silver including nanocrystalline, gelling fibers, polyurethane (PU) foam, and polymer matrix. Additionally, non-silver-based products including an extracellular polymeric substance (EPS)-dissolving antimicrobial wound gel (BDWG), a collagenase-based debriding ointment and a fish skin-based skin substitute were also evaluated. The products were evaluated on Staphylococcus aureus and Pseudomonas aeruginosa mixed-species biofilms grown using colony drip flow reactor (CDFR) and standard drip flow reactor (DFR) methodologies. Anti-biofilm efficacy was measured by viable plate counts and confocal scanning laser microscopy (CSLM). Four of the eight wound care products tested were efficacious in inhibiting growth of new biofilm when compared with untreated controls. These four products were further evaluated against mature biofilms. BDWG was the only product that achieved greater than 2-log growth reduction (5.88 and 6.58 for S. aureus and P. aeruginosa, respectively) of a mature biofilm. Evaluating both biofilm prevention and mature biofilm disruption capacity is important to a comprehensive understanding of the anti-biofilm efficacy of wound care products.

An in vitro Study of Betadine’s Ability to Eliminate Live Bacteria on the Eye: Should It Be Used for Protection against Endophthalmitis?

Background: Povidone-iodide (Betadine) is an antiseptic that is applied topically and has many uses in the medical community, such as in wound care and pre- and post-operative surgical procedures. This study was done to measure the effectiveness of Betadine solutions in inhibiting the growth of Gram-negative and Gram-positive bacteria. Methods: The ability of 2.5 and 10% Betadine solutions to inhibit bacterial growth was measured against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Acinetobacter baumannii. We grew the bacteria independently and together to simulate a hospital environment. Results: All the bacteria showed zones of inhibition. However, discs were also tested for live bacteria using the colony-forming unit assay. Complete killing was only seen for S. aureus with the 10% Betadine solution. All other bacteria showed growth on the disc. Conclusions: This study showed several things. First, the zone of inhibition assay does not give an accurate assessment of antimicrobial properties when used alone and should be followed by a colony-forming unit assay. Second, 2.5% and 5% Betadine do not have effective antimicrobial properties against any of the bacteria tested, and 10% Betadine is only effective against S. aureus and not effective against the other bacteria tested.

Urinary Catheters Coated with a Novel Biofilm Preventative Agent Inhibit Biofilm Development by Diverse Bacterial Uropathogens

Despite the implementation of stringent guidelines for the prevention of catheter-associated (CA) urinary tract infection (UTI), CAUTI remains one of the most common health care-related infections. We previously showed that an antimicrobial/antibiofilm agent inhibited biofilm development by Gram-positive and Gram-negative bacterial pathogens isolated from human infections. In this study, we examined the ability of a novel biofilm preventative agent (BPA) coating on silicone urinary catheters to inhibit biofilm formation on the catheters by six different bacterial pathogens isolated from UTIs: three Escherichia coli strains, representative of the most common bacterium isolated from UTI; one Enterobacter cloacae, a multidrug-resistant isolate; one Pseudomonas aeruginosa, common among patients with long-term catheterization; and one isolate of methicillin-resistant Staphylococcus aureus, as both a Gram-positive and a resistant organism. First, we tested the ability of these strains to form biofilms on urinary catheters made of red rubber, polyvinyl chloride (PVC), and silicone using the microtiter plate biofilm assay. When grown in artificial urine medium, which closely mimics human urine, all tested isolates formed considerable biofilms on all three catheter materials. As the biofilm biomass formed on silicone catheters was 0.5 to 1.6 logs less than that formed on rubber or PVC, respectively, we then coated the silicone catheters with BPA (benzalkonium chloride, polyacrylic acid, and glutaraldehyde), and tested the ability of the coated catheters to further inhibit biofilm development by these uropathogens. Compared with the uncoated silicone catheters, BPA-coated catheters completely prevented biofilm development by all the uropathogens, except P. aeruginosa, which showed no reduction in biofilm biomass. To explore the reason for P. aeruginosa resistance to the BPA coating, we utilized two specific lipopolysaccharide (LPS) mutants. In contrast to their parent strain, the two mutants failed to form biofilms on the BPA-coated catheters, which suggests that the composition of P. aeruginosa LPS plays a role in the resistance of wild-type P. aeruginosa to the BPA coating. Together, our results suggest that, except for P. aeruginosa, BPA-coated silicone catheters may prevent biofilm formation by both Gram-negative and Gram-positive uropathogens.

Preclinical evaluation of a commercially available biofilm disrupting wound lavage for musculoskeletal trauma

BACKGROUND

Treatment of open fractures remains a significant challenge in trauma care as these fractures are accompanied by extensive soft tissue damage, exposing the wound site to contaminants and increasing infection risk. Formation of biofilm, a capsule-like environment that acts as a barrier to treatment, is a primary mode by which infecting pathogens persist at the wound site. Therefore, a pressing need exists to identify irrigation methods that can disrupt biofilm and expose pathogens to treatment. This study aims to evaluate the antibiofilm wound lavage, Bactisure™, in comparison with saline for care of severe musculoskeletal wounds and elucidate potential effects on antibiotic treatment success.

METHODS

UAMS-1 Staphylococcus aureus biofilms were formed in vitro and treated with Bactisure™ wound lavage or sterile normal saline, alone, or in combination with sub-biofilm inhibitory levels of vancomycin. Characterization methods included quantification of biofilm biomass, quantification of viable biofilm bacteria, and biofilm matrix imaging. For in vivo assessment, a delayed treatment model of contaminated open fracture was used wherein a critical-sized defect was created in a rat femur and wound site inoculated with UAMS-1. Following a 6 h delay, wounds were debrided, irrigated with lavage of interest, and antibiotic treatments administered. Bacterial enumeration was performed on bone and hardware samples after two weeks.

RESULTS

An immediate reduction in biofilm biomass was observed in vitro following antibiofilm lavage treatment, with a subsequent 2- to 3- log reduction in viable bacteria achieved after 24 h. Furthermore, biofilms treated with antibiofilm lavage in combination with vancomycin exhibited a minor, but statistically significant, decrease in viable bacteria compared to irrigation alone. In vivo, a minor, not statistically significant, decrease in median bioburden was observed for the antibiofilm lavage compared to saline when used in combination with antibiotics. However, the percentage of bone and hardware samples with detectable bacteria was reduced from 50 to 38%.

CONCLUSIONS

These results suggest that the antibiofilm wound lavage, Bactisure™, may hold promise in mitigating infection in contaminated musculoskeletal wounds and warrants further investigation. Here, we proposed multiple mechanisms in vitro by which this antibiofilm lavage may help mitigate infection, and demonstrate this treatment slightly outperforms saline in controlling bioburden in vivo.

Advanced Wound Diagnostics: Toward Transforming Wound Care into Precision Medicine

Significance: Nonhealing wounds are an ever-growing global pandemic, with mortality rates and management costs exceeding many common cancers. Although our understanding of the molecular and cellular factors driving wound healing continues to grow, standards for diagnosing and evaluating wounds remain largely subjective and experiential, whereas therapeutic strategies fail to consistently achieve closure and clinicians are challenged to deliver individualized care protocols. There is a need to apply precision medicine practices to wound care by developing evidence-based approaches, which are predictive, prescriptive, and personalized. Recent Advances: Recent developments in "advanced" wound diagnostics, namely biomarkers (proteases, acute phase reactants, volatile emissions, and more) and imaging systems (ultrasound, autofluorescence, spectral imaging, and optical coherence tomography), have begun to revolutionize our understanding of the molecular wound landscape and usher in a modern age of therapeutic strategies. Herein, biomarkers and imaging systems with the greatest evidence to support their potential clinical utility are reviewed. Critical Issues: Although many potential biomarkers have been identified and several imaging systems have been or are being developed, more high-quality randomized controlled trials are necessary to elucidate the currently questionable role that these tools are playing in altering healing dynamics or predicting wound closure within the clinical setting. Future Directions: The literature supports the need for the development of effective point-of-care wound assessment tools, such as a platform diagnostic array that is capable of measuring multiple biomarkers at once. These, along with advances in telemedicine, synthetic biology, and "smart" wearables, will pave the way for the transformation of wound care into a precision medicine. Clinical Trial Registration number: NCT03148977.

Lugol's solution and Gentian violet eradicate methicillin-resistant Staphylococcus aureus biofilm in skin wound infections

The study aimed to evaluate the antibacterial efficacy of Lugol's solution 5% and Gentian violet 1% against methicillin-resistant Staphylococcus aureus (MRSA) biofilm in vivo. The bactericidal efficacy for treatment of MRSA-biofilm skin wound infection was tested in a murine model. Luciferase-tagged S. aureus Xen31, a MRSA-strain derived from S. aureus ATCC-3359130, was used for infection. Wounds were made in the skin of mice and infected with MRSA. The mice were treated with Lugol's solution and Gentian violet. Application of the antimicrobial agents started 24 hours post infection and was repeated daily for five-days. The antimicrobial effect on the biofilm bacteria was evaluated by measuring bioluminescence from MRSA daily for seven-days. Lugol's solution and Gentian violet showed a significant reduction in luminescent signals from the first assessment day to all subsequent days (P < .001). Lugol's solution and Gentian violet effectively eradicated MRSA in biofilm in vivo and could be alternatives or in addition to topical antibiotics when MRSA-biofilm wound infection is suspected.

Recombinant R2-pyocin cream is effective in treating Pseudomonas aeruginosa-infected wounds

Pseudomonas aeruginosa, a gram-negative opportunistic pathogen, is one of the major species isolated from infected chronic wounds. The multidrug resistance exhibited by P. aeruginosa and its ability to form biofilms that are difficult to eradicate, along with the rising cost of producing new antibiotics, has necessitated the search for alternatives to standard antibiotics. Pyocins are antimicrobial compounds produced by P. aeruginosa that protect themselves from their competitors. We synthesized and purified recombinant P. aeruginosa R2 pyocin and used it in an aqueous solution (rR2P) or formulated in polyethylene glycol (rR2PC) to treat P. aeruginosa-infected wounds. Clinical strains of P. aeruginosa were found to be sensitive (completely), partially sensitive, or resistant to rR2P. In the in vitro biofilm model, rR2P inhibited biofilm development by rR2P-sensitive isolates, while rR2PC eliminated partial biofilms formed by these strains in an in vitro wound biofilm model. In the murine model of excision wounds, and at 24 h post-infection, rR2PC application significantly reduced the bioburden of the clinical isolate BPI86. Application of rR2PC containing two glycoside hydrolase antibiofilm agents eliminated BPI86 from infected wounds. These results suggest that the topical application of rR2PC is an effective therapy for treating wounds infected with R2P-senstive P. aeruginosa strains.

The influence of a biofilm-dispersing wound gel on the wound healing process

Topical antimicrobials that reduce the bacterial bioburden within a chronically‐infected wound may have helpful or harmful effects on the healing process. We used murine models of full‐thickness skin wounds to determine the effects of the novel biofilm‐dispersing wound gel (BDWG) and its gel base on the healing of uninfected wounds. The rate of wound closure over 19 days was comparable among the BDWG‐treated (BT) wounds and the controls. Compared with the controls, histology of the BT wounds showed formation of a stable blood clot at day 1, more neovascularisation and reepithelialisation at day 3, and more organised healing at day 7. Fluorescence‐activated cell sorting analysis showed a lower percentage of neutrophils in wounded tissues of the BT group at days 1 and 3, and significantly more M2 macrophages at day 3. Levels of proinflammatory cytokines and chemokines were increased over the uninjured baseline within the wounds of all treatment groups but the levels were significantly lower in the BT group at day 1, modulating the inflammatory response. Our results suggest that BDWG does not interfere with the wound healing process and may enhance it by lowering inflammation and allowing transition to the proliferative stage of wound healing by day 3.

A Novel Biofilm-Disrupting Wound Care Technology for the Prevention of Surgical Site Infections Following Total Joint Arthroplasty: A Conceptual Review

Surgical site infections (SSIs) are a major driver for increased costs following lower extremity joint arthroplasty procedures. It has been estimated that these account for over $2 billion in annual costs in the United States. While many of the current strategies for the prevention and treatment of SSIs target planktonic bacteria, 80 to 90% of bacterial pathogens exist in a sessile state. These sessile bacteria can produce extracellular polymeric substance (EPS) as protective barriers from host immune defenses and antimicrobial agents and thus, can be exceedingly difficult to eradicate. A novel wound care gel that disrupts the EPS and destroys the inciting pathogens has been developed for the treatment and prevention of biofilm-related infections. This is achieved by the simultaneous action of four key ingredients: (1) citric acid; (2) sodium citrate; (3) benzalkonium chloride; and (4) polyethylene glycol. Together, these constituents create a high osmolarity, pH-controlled environment that deconstructs and prevents biofilm formation, while destroying pathogens and promoting a moist environment for optimal wound healing. The available clinical evidence demonstrating the efficacy of this technology has been summarized, as well as the economic implications of its implementation and the authors' preferred method of its use. Due to the multifaceted burden associated with biofilm-producing bacteria in arthroplasty patients, this technology may prove to be beneficial for patients who have higher risks for infection, or perhaps, as a prophylactic measure to prevent infections for all patients.

Evidence-Based Review of Antibiofilm Agents for Wound Care

Significance: Biofilms in vivo are small densely packed aggregations of microbes that are highly resistant to host immune responses and treatment. They attach to each other and to nearby surfaces. Biofilms are difficult to study and identify in a clinical setting as their quantification necessitates the use of advanced microscopy techniques such as confocal laser scanning microscopy. Nonetheless, it is likely that biofilms contribute to the pathophysiology of chronic skin wounds. Reducing, removing, or preventing biofilms is thus a logical approach to help clinicians heal chronic wounds. Recent Advances: Wound care products have demonstrated varying degrees of efficacy in destroying biofilms in in vitro and preclinical models, as well as in some clinical studies. Critical Issues: Controlled studies exploring the beneficial role of biofilm eradication and its relationship to healing in patients with chronic wounds are limited. This review aims to discuss the mode of action and clinical significance of currently available antibiofilm products, including surfactants, dressings, and others, with a focus on levels of evidence for efficacy in disrupting biofilms and ability to improve wound healing outcomes. Future Directions: Few available products have good evidence to support antibiofilm activity and wound healing benefits. Novel therapeutic strategies are on the horizon. More high-quality clinical studies are needed. The development of noninvasive techniques to quantify biofilms will facilitate increased ease of research about biofilms in wounds and how to combat them.

Organo-Selenium-Containing Polyester Bandage Inhibits Bacterial Biofilm Growth on the Bandage and in the Wound

The dressing material of a wound plays a key role since bacteria can live in the bandage and keep re-infecting the wound, thus a bandage is needed that blocks biofilm in the bandage. Using an in vivo wound biofilm model, we examined the effectiveness of an organo-selenium (OS)-coated polyester dressing to inhibit the growth of bacteria in a wound. Staphylococcus aureus (as well as MRSA, Methicillin resistant Staph aureus), Stenotrophomonas maltophilia, Enterococcus faecalis, Staphylococcus epidermidis, and Pseudomonas aeruginosa were chosen for the wound infection study. All the bacteria were enumerated in the wound dressing and in the wound tissue under the dressing. Using colony-forming unit (CFU) assays, over 7 logs of inhibition (100%) was found for all the bacterial strains on the material of the OS-coated wound dressing and in the tissue under that dressing. Confocal laser scanning microscopy along with IVIS spectrum in vivo imaging confirmed the CFU results. Thus, the dressing acts as a reservoir for a biofilm, which causes wound infection. The same results were obtained after soaking the dressing in PBS at 37 °C for three months before use. These results suggest that an OS coating on polyester dressing is both effective and durable in blocking wound infection.

Skin Integrity and Infection Prevention Las Vegas: the science of biofilm, a multifaceted challenge to healing

At the 4th International Skin Integrity and Infection Prevention conference, hosted by the Journal of Wound Care and the University of Huddersfield, in Las Vegas, one of the main themes was the control and resolution of biofilm. A series of reports will describe the key points of four sponsored symposia at the event. The first of these concentrates on the role of biofilm in chronic wounds and new therapies to aid the healing of these wounds by disrupting biofilm.

Cryomilled zinc sulfide: A prophylactic for Staphylococcus aureus-infected wounds

Bacterial pathogens that colonize wounds form biofilms, which protect the bacteria from the effect of host immune response and antibiotics. This study examined the effectiveness of newly synthesized zinc sulfide in inhibiting biofilm development by Staphylococcus aureus ( S. aureus) strains. Zinc sulfide (ZnS) was anaerobically biosynthesized to produce CompA, which was further processed by cryomilling to maximize the antibacterial properties to produce CompB. The effect of the two compounds on the S. aureus strain AH133 was compared using zone of inhibition assay. The compounds were formulated in a polyethylene glycol cream. We compared the effect of the two compounds on biofilm development by AH133 and two methicillin-resistant S. aureus clinical isolates using the in vitro model of wound infection. Zone of inhibition assay revealed that CompB is more effective than CompA. At 15 mg/application, the formulated cream of either compound inhibited biofilm development by AH133, which was confirmed using confocal laser scanning microscopy. At 20 mg/application, CompB inhibited biofilm development by the two methicillin-resistant S. aureus clinical isolates. To further validate the effectiveness of CompB, mice were treated using the murine model of wound infection. Colony forming cell assay and in vivo live imaging results strongly suggested the inhibition of S. aureus growth.

Albumin Inhibits Pseudomonas aeruginosa Quorum Sensing and Alters Polymicrobial Interactions

Polymicrobial interactions are complex and can influence the course of an infection, as is the case when two or more species exhibit a synergism that produces a disease state not seen with any of the individual species alone. Cell-to-cell signaling is key to many of these interactions, but little is understood about how the host environment influences polymicrobial interactions or signaling between bacteria. Chronic wounds are typically polymicrobial, with Staphylococcus aureus and Pseudomonas aeruginosa being the two most commonly isolated species. While P. aeruginosa readily kills S. aureusin vitro, the two species can coexist for long periods together in chronic wound infections. In this study, we investigated the ability of components of the wound environment to modulate interactions between P. aeruginosa and S. aureus We demonstrate that P. aeruginosa quorum sensing is inhibited by physiological levels of serum albumin, which appears to bind and sequester some homoserine lactone quorum signals, resulting in the inability of P. aeruginosa to produce virulence factors that kill S. aureus These data could provide important clues regarding the virulence of P. aeruginosa in albumin-depleted versus albumin-rich infection sites and an understanding of the nature of friendly versus antagonistic interactions between P. aeruginosa and S. aureus.

Disrupting the biofilm matrix improves wound healing outcomes

OBJECTIVE

The most unyielding molecular component of biofilm communities is the matrix structure that it can create around the individual microbes that constitute the biofilm. The type of polymeric substances (polymeric sugars, bacterial proteins, bacterial DNA and even co-opted host substances) are dependent on the microbial species present within the biofilm. The extracellular polymeric substances that make up the matrix give the wound biofilm incredible colony defences against host immunity, host healing and wound care treatments. This polymeric slime layer, which is secreted by bacteria, encases the population of microbes, creating a physical barrier that limits the ingress of treatment agents to the bacteria. The aim of this study was to determine if degrading the wound biofilm matrix would improve wound healing outcomes and if so, if there was a synergy between treating agents that disrupted biofilm defenses with Next Science Wound Gel (wound gel) and cidal agents (topical antibiotics).

METHOD

A three-armed randomised controlled trial was designed to determine if standard of care (SOC) was superior to SOC plus wound gel (SOC + gel) and wound gel alone. The wound gel used in this study contains components that directly attack the biofilm extracellular polymeric substance. The gel was applied directly to the wound bed on a Monday-Wednesday-Friday interval, either alone or with SOC topical antibiotics.

RESULTS

Using a surrogate endpoint of 50% reduction in wound volume, the results showed that SOC healed at 53%, wound gel healed at 80%, while SOC plus wound gel showed 93% of wounds being successfully treated.

CONCLUSION

By directly targeting the wound biofilm matrix, wound healing outcomes are improved.

The antimicrobial agent, Next-Science, inhibits the development of Staphylococcus aureus and Pseudomonas aeruginosa biofilms on tympanostomy tubes

OBJECTIVE

The purpose of this study was to determine if the recently developed novel antimicrobial/antibiofilm agent Next-Science (NS) inhibits biofilm development by Staphylococcus aureus or Pseudomonas aeruginosa on tympanostomy tubes (TT) and to define the concentration of NS at which this inhibition occurs.

METHODS

Preliminary titration experiments determined the effective concentrations of NS that completely inhibit the planktonic growth of S. aureus and P. aeruginosa. Since NS has the potential to inhibit both planktonic growth and biofilm development, we examined the antibiofilm effect using the established concentrations that inhibited planktonic growth. Biofilms developed on TT using the microtiter plate assay were assessed quantitatively by determining the number of microorganisms per tube (CFU/tube) and qualitatively by visualization with confocal laser scanning microscopy (CLSM).

RESULTS

Planktonic growth of S. aureus and P. aeruginosa was inhibited by 20.3 μg/mL and 325 μg/mL of NS, respectively. While S. aureus and P. aeruginosa formed well-developed biofilms on TT at 24 h without treatment, addition of the indicated concentrations of NS at the time of inoculation of the TT inhibited the formation of biofilms by both organisms. CLSM confirmed the absence of biofilms on either the inner or outer surface of the treated TTs. At 8 h post-inoculation, P. aeruginosa formed a partial biofilm on the TT when untreated. In comparison, the NS-treated biofilms failed to develop further and the CFU/TT were significantly reduced.

CONCLUSION

The novel antimicrobial agent NS inhibited the development of S. aureus and P. aeruginosa biofilms on TTs. The same concentrations of NS inhibited both planktonic growth and biofilm development.

Novel approaches to combat bacterial biofilms

Biofilms formed by pathogenic bacteria and fungi are associated with a wide range of diseases, from device-related infections (such as catheters or prosthetic joints) to chronic infections occurring on native tissues (such as lung infections in cystic fibrosis patients). Biofilms are therefore responsible for an important medical and economic burden. Currently used antibiotics have mostly been developed to target exponentially growing microorganisms and are poorly effective against biofilms. In particular, even high concentrations of bactericidal antibiotics are inactive against a subset of persistent biofilm bacteria, which can cause infection recurrence despite prolonged treatments. While the search for a magic bullet antibiotic effective against both planktonic and biofilm bacteria is still active, alternative preventive and curative approaches are currently being developed either limiting adhesion or biofilm formation or targeting biofilm tolerance by killing persister bacteria. Most of these approaches are adjunctive using new molecules in combination with antibiotics. This review presents promising approaches or strategies that could improve our ability to prevent or eradicate bacterial biofilms in medical settings.