Enhancement of bactericidal effects of bacteriophage and gentamicin combination regimen against Staphylococcus aureus and Pseudomonas aeruginosa strains in a mice diabetic wound model.

Diabetic patients are more susceptible to developing wound infections resulting in poor and delayed wound healing. Bacteriophages, the viruses that target-specific bacteria, can be used as an alternative to antibiotics to eliminate drug-resistant bacterial infections. Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) are among the most frequently identified pathogens in diabetic foot ulcers (DFUs). The aim of this study was assessment of bacteriophage and gentamicin combination effects on bacterial isolates from DFU infections. Specific bacteriophages were collected from sewage and animal feces samples and the phages were enriched using S. aureus and P. aeruginosa cultures. The lytic potential of phage isolates was assessed by the clarity of plaques. We isolated and characterized four lytic phages: Stp2, Psp1, Stp1, and Psp2. The phage cocktail was optimized and investigated in vitro. We also assessed the effects of topical bacteriophage cocktail gel on animal models of DFU. Results revealed that the phage cocktail significantly reduced the mortality rate in diabetic infected mice. We determined that treatment with bacteriophage cocktail effectively decreased bacterial colony counts and improved wound healing in S. aureus and P. aeruginosa infections, especially when administrated concomitantly with gentamicin. The application of complementary therapy using a phage cocktail and gentamicin, could offer an attractive approach for the treatment of wound diabetic bacterial infections.

Membrane lipid renovation in Pseudomonas aeruginosa - implications for phage therapy?

Pseudomonas aeruginosa is an important Gram-negative pathogen with intrinsic resistance to many clinically used antibiotics. It is particularly troublesome in nosocomial infections, immunocompromised patients, and individuals with cystic fibrosis. Antimicrobial resistance (AMR) is a huge threat to global health, with a predicted 10 million people dying from resistant infections by 2050. A promising therapy for combatting AMR infections is phage therapy. However, more research is required to investigate mechanisms that may influence the efficacy of phage therapy. An important overlooked aspect is the impact of membrane lipid remodelling on phage binding ability. P. aeruginosa undergoes changes in membrane lipids when it encounters phosphorus stress, an environmental perturbation that is likely to occur during infection. Lipid changes include the substitution of glycerophospholipids with surrogate glycolipids and the over-production of ornithine-containing aminolipids. Given that membrane lipids are known to influence the structure and function of membrane proteins, we propose that changes in the composition of membrane lipids during infection may alter phage binding and subsequent phage infection dynamics. Consideration of such effects needs to be urgently prioritised in order to develop the most effective phage therapy strategies for P. aeruginosa infections.

Acceleration of cutaneous wound healing by Lucilia sericata maggots in diabetic Wistar rats.

The study was aimed to evaluate the effectiveness of maggot therapy in healing of cutaneous infected wound in streptozotocin (STZ) induced diabetic Wistar rat. For live maggots, the sterilized eggs of Lucilia sericata were obtained from colonies established in laboratory. Diabetes model was established in 48 male Wister rat by intra-peritoneal injection of STZ at the dose of 60 mg/kg body-weight. Cutaneous wounds exposed with mixed colonies of bacteria like Staphylococcus aureus, E. coli and Pseudomonas aeruginosa were prepared in all rat. The animals equally divided in 4 groups with 12 rats each being presented as treatment group of control, antibiotic, maggot and maggot with antibiotic in combination. All treatments were done once and hold for 24 hours. Wound kinetics and bacterial bio burden were measured at weekly interval to till complete healing. Significant reduction in wound area with maximum contraction was found (>95%) in maggot treated group when compared to antibiotic treated (79%) and control (72%). In maggot as well as maggot and antibiotic in combination group showed early elimination of bacterial bio-burden 7.88±0.03log CFU/ml to 1.12±0.65log CFU/ml and 7.86±0.04) log CFU/ml to 1.54±0.52log CFU/ml respectively in three weeks of time. Early healing indication was also experienced on histomorphological examination of wounded tissue of maggot treated groups by early and better epithelialization, collagenation and neovascularization with complete healing of wound in three weeks in comparison to antibiotic and control respectively. However, the present study did not show any difference in healing of wound with use of maggot alone or in antibiotic combination. Live maggot of Lucilia sericata effectively lower bacterial bioburden and and accelerate healing of infected cutaneous wound in diabetic conditions.

Improving the Inhibitory Effect of Phages against Pseudomonas aeruginosa Isolated from a Burn Patient Using a Combination of Phages and Antibiotics.

Antibiotic resistance causes around 700,000 deaths a year worldwide. Without immediate action, we are fast approaching a post-antibiotic era in which common infections can result in death. Pseudomonas aeruginosa is the leading cause of nosocomial infection and is also one of the three bacterial pathogens in the WHO list of priority bacteria for developing new antibiotics against. A viable alternative to antibiotics is to use phages, which are bacterial viruses. Yet, the isolation of phages that efficiently kill their target bacteria has proven difficult. Using a combination of phages and antibiotics might increase treatment efficacy and prevent the development of resistance against phages and/or antibiotics, as evidenced by previous studies. Here, in vitro populations of a Pseudomonas aeruginosa strain isolated from a burn patient were treated with a single phage, a mixture of two phages (used simultaneously and sequentially), and the combination of phages and antibiotics (at sub-minimum inhibitory concentration (MIC) and MIC levels). In addition, we tested the stability of these phages at different temperatures, pH values, and in two burn ointments. Our results show that the two-phages-one-antibiotic combination had the highest killing efficiency against the P. aeruginosa strain. The phages tested showed low stability at high temperatures, acidic pH values, and in the two ointments. This work provides additional support for the potential of using combinations of phage-antibiotic cocktails at sub-MIC levels for the treatment of multidrug-resistant P. aeruginosa infections.

High-Voltage, Pulsed Electric Fields Eliminate Pseudomonas aeruginosa Stable Infection in a Mouse Burn Model.

Objective: The incidence of severe infectious complications after burn injury increases mortality by 40%. However, traditional approaches for managing burn infections are not always effective. High-voltage, pulsed electric field (PEF) treatment shortly after a burn injury has demonstrated an antimicrobial effect in vivo; however, the working parameters and long-term effects of PEF treatment have not yet been investigated. Approach: Nine sets of PEF parameters were investigated to optimize the applied voltage, pulse duration, and frequency or pulse repetition for disinfection of Pseudomonas aeruginosa infection in a stable mouse burn wound model. The bacterial load after PEF administration was monitored for 3 days through bioluminescence imaging. Histological assessments and inflammation response analyses were performed at 1 and 24 h after the therapy. Results: Among all tested PEF parameters, the best disinfection efficacy of P. aeruginosa infection was achieved with a combination of 500 V, 100 µs, and 200 pulses delivered at 3 Hz through two plate electrodes positioned 1 mm apart for up to 3 days after the injury. Histological examinations revealed fewer inflammatory signs in PEF-treated wounds compared with untreated infected burns. Moreover, the expression levels of multiple inflammatory-related cytokines (interleukin [IL]-1α/ß, IL-6, IL-10, leukemia inhibitory factor [LIF], and tumor necrosis factor-alpha [TNF-α]), chemokines (macrophage inflammatory protein [MIP]-1α/ß and monocyte chemoattractant protein-1 [MCP-1]), and inflammation-related factors (vascular endothelial growth factor [VEGF], macrophage colony-stimulating factor [M-CSF], and granulocyte-macrophage colony-stimulating factor [G-CSF]) were significantly decreased in the infected burn wound after PEF treatment. Innovation: We showed that PEF treatment on infected wounds reduces the P. aeruginosa load and modulates inflammatory responses. Conclusion: The data presented in this study suggest that PEF treatment is a potent candidate for antimicrobial therapy for P. aeruginosa burn infections.

Characterization of different alginate lyases for dissolving Pseudomonas aeruginosa biofilms.

Aggregates of Pseudomonas aeruginosa form a protective barrier against antibiotics and the immune system. These barriers, known as biofilms, are associated with several infectious diseases. One of the main components of these biofilms is alginate, a homo- and hetero-polysaccharide that consists of ß-D-mannuronate (M) and α-L-guluronate (G) units. Alginate lyases degrade this sugar and have been proposed as biotherapeutic agents to dissolve P. aeruginosa biofilms. However, there are contradictory reports in the literature regarding the efficacy of alginate lyases against biofilms and their synergistic effect with antibiotics. We found that most positive reports used a commercial crude extract from Flavobacterium multivorum as the alginate lyase source. By using anion exchange chromatography coupled to nano LC MS/MS, we identified two distinct enzymes in this extract, one has both polyM and polyG (polyM/G) degradation activities and it is similar in sequence to a broad-spectrum alginate lyase from Flavobacterium sp. S20 (Alg2A). The other enzyme has only polyG activity and it is similar in sequence to AlyA1 from Zobellia galactanivorans. By characterizing both of these enzymes together with three recombinant alginate lyases (a polyM, a polyG and a polyM/G), we showed that only enzymes with polyM/G activity such as Alg2A and A1-II' (alginate lyase from Sphingomonas sp.) are effective in dissolving biofilms. Furthermore, both activities are required to have a synergistic effect with antibiotics.

Controlled phage therapy by photothermal ablation of specific bacterial species using gold nanorods targeted by chimeric phages.

The use of bacteriophages (phages) for antibacterial therapy is under increasing consideration to treat antimicrobial-resistant infections. Phages have evolved multiple mechanisms to target their bacterial hosts, such as high-affinity, environmentally hardy receptor-binding proteins. However, traditional phage therapy suffers from multiple challenges stemming from the use of an exponentially replicating, evolving entity whose biology is not fully characterized (e.g., potential gene transduction). To address this problem, we conjugate the phages to gold nanorods, creating a reagent that can be destroyed upon use (termed "phanorods"). Chimeric phages were engineered to attach specifically to several Gram-negative organisms, including the human pathogens Escherichia coli, Pseudomonas aeruginosa, and Vibrio cholerae, and the plant pathogen Xanthomonas campestris The bioconjugated phanorods could selectively target and kill specific bacterial cells using photothermal ablation. Following excitation by near-infrared light, gold nanorods release energy through nonradiative decay pathways, locally generating heat that efficiently kills targeted bacterial cells. Specificity was highlighted in the context of a P. aeruginosa biofilm, in which phanorod irradiation killed bacterial cells while causing minimal damage to epithelial cells. Local temperature and viscosity measurements revealed highly localized and selective ablation of the bacteria. Irradiation of the phanorods also destroyed the phages, preventing replication and reducing potential risks of traditional phage therapy while enabling control over dosing. The phanorod strategy integrates the highly evolved targeting strategies of phages with the photothermal properties of gold nanorods, creating a well-controlled platform for systematic killing of bacterial cells.

Blue laser light inhibits biofilm formation in vitro and in vivo by inducing oxidative stress.

Resolution of bacterial infections is often hampered by both resistance to conventional antibiotic therapy and hiding of bacterial cells inside biofilms, warranting the development of innovative therapeutic strategies. Here, we report the efficacy of blue laser light in eradicating Pseudomonas aeruginosa cells, grown in planktonic state, agar plates and mature biofilms, both in vitro and in vivo, with minimal toxicity to mammalian cells and tissues. Results obtained using knock-out mutants point to oxidative stress as a relevant mechanism by which blue laser light exerts its anti-microbial effect. Finally, the therapeutic potential is confirmed in a mouse model of skin wound infection. Collectively, these data set blue laser phototherapy as an innovative approach to inhibit bacterial growth and biofilm formation, and thus as a realistic treatment option for superinfected wounds.

Application of Lactobacillus gasseri 63 AM supernatant to Pseudomonas aeruginosa-infected wounds prevents sepsis in murine models of thermal injury and dorsal excision.

Introduction. Severely burned patients are susceptible to bacterial infection within their burn wounds, which frequently leads to sepsis, multiple organ failure and death. The opportunistic pathogen Pseudomonas aeruginosa, an organism inherently resistant to multiple antibiotics, is a common cause of sepsis in these patients.Aim. Development of a topical treatment unrelated to conventional antibiotics is essential for prevention of P. aeruginosa infection and sepsis, leading to a role for the direct application of probiotics or their by-products.Methodology. We examined the effectiveness of 20× concentrated supernatant from Lactobacillus gasseri strain 63 AM (LgCS) grown in de Man, Rogosa and Sharpe broth in inhibiting P. aeruginosa biofilms in vitro, as well as in reducing wound bioburden and P. aeruginosa sepsis in vivo.Results. LgCS inhibited the growth of P. aeruginosa strain PAO1, prevented its biofilm development and eliminated partially developed PAO1 biofilms. In the murine model of thermal injury, a single injection of LgCS following injury and PAO1 infection reduced mortality to 0 % and prevented systemic spread (sepsis). Furthermore, a second injection of LgCS 24 h after the first eliminated PAO1 from the wound. In the murine dorsal excision infection model, either LgCS or ceftazidime treatment of the PAO1-infected wound significantly reduced the mortality rate among infected mice, while combining LgCS with ceftazidime eliminated mortality.Conclusion. These results suggest the potential of LgCS in preventing sepsis from P. aeruginosa infection in severely burned and other immunocompromised patients.

Bacteriophage PEV20 and Ciprofloxacin Combination Treatment Enhances Removal of Pseudomonas aeruginosa Biofilm Isolated from Cystic Fibrosis and Wound Patients.

Antibiotic resistance in Pseudomonas aeruginosa biofilms necessitates the need for novel antimicrobial therapy with anti-biofilm properties. Bacteriophages (phages) are recognized as an ideal biopharmaceutical for combating antibiotic-resistant bacteria especially when used in combination with antibiotics. However, previous studies primarily focused on using phages against of P. aeruginosa biofilms of laboratory strains. In the present study, biofilms of six P. aeruginosa isolated from cystic fibrosis and wound patients, and one laboratory strain was treated singly and with combinations of anti-Pseudomonas phage PEV20 and ciprofloxacin. Of these strains, three were highly susceptible to the phage, while one was partially resistant and one was completely resistant. Combination treatment with PEV20 and ciprofloxacin enhanced biofilm eradication compared with single treatment. Phage and ciprofloxacin synergy was found to depend on phage-resistance profile of the target bacteria. Furthermore, phage and ciprofloxacin combination formulation protected the lung epithelial and fibroblast cells from P. aeruginosa and promoted cell growth. The results demonstrated that thorough screening of phage-resistance is crucial for designing phage-antibiotic formulation. The addition of highly effective phage could reduce the ciprofloxacin concentration required to combat P. aeruginosa infections associated with biofilm in cystic fibrosis and wound patients.

Mechanistic research holds promise for bacterial vaccines and phage therapies for Pseudomonas aeruginosa.

Vaccines for Pseudomonas aeruginosa have been of longstanding interest to immunologists, bacteriologists, and clinicians, due to the widespread prevalence of hospital-acquired infection. As P. aeruginosa becomes increasingly antibiotic resistant, there is a dire need for novel treatments and preventive vaccines. Despite intense efforts, there currently remains no vaccine on the market to combat this dangerous pathogen. This article summarizes current and past vaccines under development that target various constituents of P. aeruginosa. Targeting lipopolysaccharides and O-antigens have shown some promise in preventing infection. Recombinant flagella and pili that target TLR5 have been utilized to combat P. aeruginosa by blocking its motility and adhesion. The type 3 secretion system components, such as needle-like structure PcrV or exotoxin PopB, are also potential vaccine targets. Outer membrane proteins including OprF and OprI are newer representatives of vaccine candidates. Live attenuated vaccines are a focal point in this review, and are also considered for novel vaccines. In addition, phage therapy is revived as an effective option for treating refractory infections after failure with antibiotic treatment. Many of the aforementioned vaccines act on a single target, thus lacking a broad range of protection. Recent studies have shown that mixtures of vaccines and combination approaches may significantly augment immunogenicity, thereby increasing their preventive and therapeutic potential.

Grape pomace flour alleviates Pseudomonas aeruginosa-induced hepatic oxidative stress in grass carp by improving antioxidant defense.

Pseudomonas aeruginosa is a Gram-negative opportunistic bacterial pathogen in aquaculture systems being associated to extensive liver damage caused by oxidative stress in both marine and freshwater fish. Dietary supplementation with natural antioxidants is considered a rational strategy to prevent hepatic diseases involved with oxidative stress. Bio-residues resulting from the wine industry, such as grape pomace, are potential sources of bioactive phenolic compounds that can be applied as supplement for animal production. Thus, the aim of this study was to evaluate whether dietary supplementation with grape pomace flour (GPF) was able to prevent or reduce the hepatic oxidative damage of grass carp, Ctenopharyngodon idella, experimentally infected by P. aeruginosa. Hepatic reactive oxygen species (ROS), metabolites of nitric oxide (NOx), thiobarbituric acid reactive substances, and protein carbonylation levels were higher in fish experimentally infected by P. aeruginosa compared to the control group. Hepatic superoxide dismutase and catalase activities and antioxidant capacity against peroxyl radical levels were also higher in fish experimentally infected by P. aeruginosa compared to the control group. Dietary supplementation with 300 mg/kg GPF prevented all alterations elicited by P. aeruginosa, with the exception of protein carbonylation levels. The dietary supplementation with 150 mg/kg GPF was not able to avoid alteration of the analyzed variables, being results similar to those infected (positive control). Based on these results, dietary supplementation with 300 mg/kg GPF prevented P. aeruginosa-induced liver damage in grass carp, and this protective effect occurred through prevention on excessive ROS and NOx production, as well as via prevention of lipid damage. Moreover, 300 mg/kg GPF exerted its hepatoprotective effects by improving enzymatic and non-enzymatic antioxidant defense system. In summary, this supplementation can be an interesting approach to prevent P. aeruginosa-induced liver damage.

Efficacy of Maggot Therapy on Staphylococcus aureus and Pseudomonas aeruginosa in Diabetic Foot Ulcers: A Randomized Controlled Trial.

PURPOSE: This study was conducted to evaluate the antimicrobial effects of medicinal maggots of Lucilia sericata on Staphylococcus aureus and Pseudomonas aeruginosa on diabetic foot ulcers (DFUs). DESIGN: Randomized controlled trial. SUBJECTS AND SETTING: The sample comprised 50 adult patients from the clinic of the Academic Center for Education, Culture and Research of Tehran University of Medical Sciences, Iran. All participants who had at least 1 DFU present for at least 12 weeks, an arterial brachial index value of more than 0.6, and a hemoglobin A1c value of less than 8% were included in this study. METHODS: Subjects were randomly selected for the maggot-treated (treatment) or conventional treatment (control) group. Conventional treatments such as antibiotic therapy, debridement, and offloading were done for both groups, but maggot therapy (MT) was added to the protocol of the treatment group. Bacterial burden was monitored and compared for both groups using cultures collected using swab technique. Wound secretions were measured and compared in both groups. RESULTS: The number of infected cases with S aureus in the treatment group was significantly reduced after 48 hours in comparison with the control group (P = .047). The number of infected cases with P aeruginosa was significantly reduced after 96 hours (P = .002). We also found that wound secretions in the treatment group were significantly higher than in the control group (P < .00). CONCLUSIONS: Our findings indicate that MT is a safe and efficacious treatment of DFUs.

The Modular Adaptive Electrotherapy Delivery System (MAEDS): An Electroceutical Approach for Effective Treatment of Wound Infection and Promotion of Healing.

BACKGROUND: Infected wounds are painful and cannot heal, with antibiotics showing reduced efficacy. Appropriate wound electrotherapy may limit incident planktonic and polymicrobial colonization, inhibit biofilm formation and accelerate healing. METHODS: The Modular Adaptive Electrotherapy Delivery System (MAEDS) is a lightweight, flexible, battery-powered disposable bandage which delivers controlled reliable electrotherapy to the wound for up to 7 days. Large full-thickness excisional wounds (6 cm diameter) were created in a porcine model and freshly cultured 0.5 McFarland green fluorescent protein-labeled Pseudomonas aeruginosa evenly applied to the wound bed. Control wounds received standard wound care, Tegaderm HP Transparent Dressing (3 M Health Care, St. Paul, MN, USA) applied in a sterile fashion. Treatment wounds received MAEDS electrotherapy for up to 28 days or until healed. Onboard Bluetooth facilitated remote real-time monitoring of MAEDS function. Dressing changes occurred on postoperative day (POD) 1, 3, 5, 7, 10, 14, 21, and 28. Punch biopsies were taken at the wound margin and center. Bacterial samples were processed to determine infection status. RESULTS: Acute infected wounds treated with MAEDS electrotherapy were 92% smaller than baseline by POD21. Healing rate was significantly faster (p < 0.01) and infection significantly decreased (p < 0.0001) at POD10, relative to control wounds. CONCLUSION: The MAEDS electrotherapy can significantly inhibit infection and enhance healing rate in acute infected wounds.

A Biomimetic Non-Antibiotic Approach to Eradicate Drug-Resistant Infections.

The chronic infections by pathogenic Pseudomonas aeruginosa (P. aeruginosa) remain to be properly addressed. In particular, for drug-resistant strains, limited medication is available. An in vivo pneumonia model induced by a clinically isolated aminoglycoside resistant strain of P. aeruginosa is developed. Tobramycin clinically treating P. aeruginosa infections is found to be ineffective to inhibit or eliminate this drug-resistant strain. Here, a newly developed non-antibiotics based nanoformulation plus near-infrared (NIR) photothermal treatment shows a remarkable antibacterial efficacy in treating this drug-resistant pneumonia. The novel formulation contains 50-100 nm long nanorods decorated with two types of glycomimetic polymers to specifically block bacterial LecA and LecB lectins, respectively, which are essential for bacterial biofilm development. Such a 3D display of heteromultivalent glycomimetics on a large scale is inspired by the natural strengthening mechanism for the carbohydrate-lectin interaction that occurs when bacteria initially infects the host. This novel formulation shows the most efficient bacteria inhabitation and killing against P. aeruginosa infection, through lectin blocking and the near-infrared-light-induced photothermal effect of gold nanorods, respectively. Collectively, the novel biomimetic design combined with the photothermal killing capability is expected to be an alternative treatment strategy against the ever-threatening drug-resistant infectious diseases when known antibiotics have failed.

Antibacterial and antioxidant activity of different types of honey derived from Mount Olympus in Greece.

The aim of the present study was to examine the antioxidant and antibacterial activity of 21 types of honey derived from Mount Olympus (Mt. Olympus), a region with great plant biodiversity. The antibacterial activity was examined against the growth of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) by the agar well diffusion assay and the determination of the minimum inhibitory concentration (MIC). The antioxidant activity was assessed by using the 2,2­diphenyl­1­picrylhydrazyl (DPPH) and 2,2'­azino­bis(3­ethylbenzothiazoline­6­sulphonic acid (ABTS•+) free radical scavenging assays. These activities were compared to Manuka honey which is used as an alternative medicine. The results revealed that all tested honey types exhibited antibacterial activity against S. aureus and P. aeruginosa. The MIC of the tested honey types against S. aureus ranged from 3.125 to 12.5% (v/v), while MIC of Manuka honey was determined to be 6.25% (v/v). The MIC values of the tested honey types against P. aeruginosa ranged from 6.25 to 12.5% (v/v) and the MIC of Manuka honey was determined at 12.5% (v/v). Moreover, the results suggested that the presence of hydrogen peroxide and proteinaceous compounds in the honey types accounted, at least in part, for the antibacterial activity. In addition, the total polyphenolic content (TPC) of the honey types seemed to contribute to the antibacterial activity against P. aeruginosa. Furthermore, some of the tested honey types exhibited potent free radical scavenging activity against DPPH and ABTS•+ radicals, which was greater than that of Manuka honey. The results indicated that not only the quantity, but also the quality of the polyphenols were responsible for the antioxidant activity. Moreover, four honey types exhibiting great antioxidant activity were converted to powder using a freeze drying method. The results indicated that following conversion to powder all honey types, apart from one, retained their antioxidant activity, although their TPC was reduced. On the whole, and at least to the best of our knowledge, the present study is the first that extensively examined the bioactivities of different types of honey derived from Mt. Olympus.

Immunization with Pseudomonas aeruginosa outer membrane vesicles stimulates protective immunity in mice.

Pseudomonas aeruginosa is an opportunistic pathogen responsible for a wide range of severe nosocomial and community acquired infections, these infections are major health problems for cystic fibrosis patients and immune-compromised individuals. The emergence of multidrug-resistant isolates highlights the need to develop alternative strategies for treatment of P. aeruginosa infections. Outer membrane vesicles (OMVs) are spherical nanometer-sized proteolipids that are secreted from numerous of pathogenic Gram-negative bacteria, and a number of studies have confirmed the protective efficacy for use of OMVs as candidate vaccines. In this study, OMVs from P. aeruginosa (PA_OMVs) were isolated, formulated with aluminum phosphate adjuvant and used as a vaccine in a mouse model of acute lung infection. The results confirmed that active immunization with PA_OMVs was able to reduce bacterial colonization, cytokine secretion and tissue damage in the lung tissue, thus protecting mice from lethal challenge of P. aeruginosa. Cytokines assay validated that immunization with PA_OMVs was efficient to induce a mixed cellular immune response in mice. Further, high level of specific antibodies was detected in mice immunized with PA_OMVs, and results from opsonophagocytic killing assay and passive immunization suggested that humoral immune response may be critical for PA_OMVs mediated protection. These findings demonstrated that PA_OMVs may be served as a novel candidate vaccine for the prevention of P. aeruginosa infection.

Preclinical therapeutic efficacy of the ciprofloxacin-eluting sinus stent for Pseudomonas aeruginosa sinusitis.

BACKGROUND: The ciprofloxacin-coated sinus stent (CSS) has unique therapeutic potential to deliver antibiotics to the sinuses. The objective of this study is to evaluate the efficacy of the CSS stent in eliminating Pseudomonas aeruginosa infection in a rabbit model of sinusitis. METHODS: A ciprofloxacin-eluting sinus stent was created by coating ciprofloxacin/Eudragit RS100 on biodegradable poly-D/L-lactic acid (2 mg). After analyzing in-vitro inhibition of P aeruginosa (PAO-1 strain) biofilm formation, a total of 8 stents (4 shams, 4 CSSs) were placed unilaterally in rabbit maxillary sinuses via dorsal sinusotomy after inducing infection for 1 week with PAO-1. Animals were assessed 2 weeks after stent insertion with nasal endoscopy, sinus culture, computed tomography (CT) scan, histopathology, and scanning electron microscopy (SEM). RESULTS: PAO-1 biofilm formation was significantly reduced in vitro with exposure to the CSS (p < 0.0001). Insertion of the stent in PAO-1-infected rabbits for 2 weeks resulted in significant improvement in sinusitis according to endoscopy scoring (p < 0.0001) and CT scoring (p < 0.002). Histology and SEM revealed marked improvement in the structure of the mucosa and submucosa with no detection of biofilm structures in the CSS cohort. CONCLUSION: Although this study had a small sample size, we identified robust therapeutic efficacy of the CSS by reducing bacterial load and biofilm formation of P aeruginosa in a preclinical model of sinusitis after placement for 2 weeks.

Employing high-frequency alternating magnetic fields for the non-invasive treatment of prosthetic joint infections.

Treatment of prosthetic joint infection (PJI) usually requires surgical replacement of the infected joint and weeks of antibiotic therapy, due to the formation of biofilm. We introduce a non-invasive method for thermal destruction of biofilm on metallic implants using high-frequency (>100 kHz) alternating magnetic fields (AMF). In vitro investigations demonstrate a >5-log reduction in bacterial counts after 5 minutes of AMF exposure. Confocal and scanning electron microscopy confirm removal of biofilm matrix components within 1 minute of AMF exposure, and combination studies of antibiotics and AMF demonstrate a 5-log increase in the sensitivity of Pseudomonas aeruginosa to ciprofloxacin. Finite element analysis (FEA) simulations demonstrate that intermittent AMF exposures can achieve uniform surface heating of a prosthetic knee joint. In vivo studies confirm thermal damage is confined to a localized region (<2 mm) around the implant, and safety can be achieved using acoustic monitoring for the presence of surface boiling. These initial studies support the hypothesis that AMF exposures can eradicate biofilm on metal implants, and may enhance the effectiveness of conventional antibiotics.

Terapia fotodinámica con azul de metileno en úlceras cutáneas infectadas con Pseudomonas aeruginosa y Fusarium spp / Photodynamic Therapy With Methylene Blue for Skin Ulcers Infected With Pseudomonas aeruginosa and Fusarium spp

La terapia fotodinámica tiene una importante acción antimicrobiana. Se presentan 2 casos clínicos de úlceras crónicas en las extremidades inferiores sobreinfectadas por hongos y bacterias de difícil manejo, en los que el tratamiento fotodinámico con azul de metileno como fotosensibilizante resultó en la curación clínica y microbiológica. No se presentaron efectos adversos reseñables. La posibilidad de utilizar la terapia fotodinámica con azul de metileno en el manejo de las úlceras crónicas sobreinfectadas constituye una interesante alternativa para reducir el uso de antibióticos y disminuir la aparición de resistencias (AU)

Photodynamic therapy (PDT) is a therapeutic modality with significant antimicrobial activity. We present 2 cases of chronic lower limb ulcers in which fungal and bacterial superinfection complicated management. PDT with methylene blue as the photosensitizer led to clinical and microbiological cure with no significant adverse effects. PDT with methylene blue is a valid option for the management of superinfected chronic ulcers, reducing the use of antibiotics and the induction of resistance (AU)