Biofilm Eradication Research Articles

Polyphenolic Nano-formulations: A New Avenue against Bacterial Infection.

The gradual emergence of new bacterial strains impervious to one or more antibiotics necessitates discovering and applying natural alternatives. Among natural products, various polyphenols exhibit antibacterial activity. However, polyphenols with biocompatible and potent antibacterial characteristics are limited due to low aqueous solubility and bioavailability; therefore, recent studies are considering new polyphenol formulations. Nanoformulations of polyphenols, especially metal nanoparticles, are currently being investigated for their potential antibacterial activity. Nanonization of such products increases their solubility and helps attain a high surface-to-volume ratio and, therefore, a higher reactivity of the nanonized products with better remedial potential than nonnanonized products. Polyphenolic compounds with catechol and pyrogallol moieties efficiently bond with many metal ions, especially Au and Ag. These synergistic effects exhibit antibacterial pro-oxidant ROS generation, membrane damage, and biofilm eradication. This review discusses various nano-delivery systems for considering polyphenols as antibacterial agents.

Antibiofilm and antivirulence efficacy of Pleurotus platypus methanolic extract against Staphylococcus aureus through ROS generation and cell membrane disruption

Multi-drug resistance is recognized as a significant worldwide public health concern in the current century. Biofilm formation further exacerbates bacterial resistance to antibacterial medications, host immunological responses, and phagocytosis, resulting in long-lasting chronic illnesses. Investigating natural resources is a very potent approach for developing alternative anti-infective medications to effectively control multi-drug resistant bacterial infections. In this study, a unique mushroom species namely Pleurotus platypus had been discovered from the Terai-Duars region of West Bengal, India. The myco-chemical profiling and preliminary chemical analysis of Pleurotus platypus methanolic extract determined the significant presence of metabolites belonging to several major chemical classes such as flavonoid, alkaloid, triterpenoid, polyphenol, benzoic acids, coumarin, flavone etc. Most intriguingly, the extract possessed effective antibacterial, antibiofilm and antivirulence properties against Staphylococcus aureus and Methicillin resistant Staphylococcus aureus, one of the most notable drug-resistant opportunistic and nosocomial pathogens. Mechanistically, the mushroom extract enhanced the production of Reactive Oxygen Species (ROS) inside the targeted bacteria, causing alterations in membrane potential, damage to the cellular membrane and further release of intracellular DNA, destined to cell death. Moreover, the methanolic extract reported the eradication of pre-existing biofilms from the urinary catheter surface, hinting towards its future application in the related field. To summarize, Pleurotus platypus methanolic extract could be an excellent alternative antibacterial and antibiofilm therapeutic candidate for the effective management of Staphylococcus infections with improved outcome.

Transcytosable and Ultrasound-Activated Liposome Enables Deep Penetration of Biofilm for Surgical Site Infection Management.

Biofilm-associated surgical site infection (BSSI) is a common and grievous postoperative complication lacking effective remedies, mainly due to the poor drug accumulation and penetration in the biofilms featured by dense extracellular polymeric substances (EPSs). Here, it is found that the vascular cell adhesion molecule-1 (VCAM1) is highly overexpressed in the vascular cells of BSSI. It is proposed that the combination of VCAM1-mediated transcytosis and ultrasonic cavitation can consecutively overcome the biological barriers of vascular endothelial cells and EPS for biofilm eradication. To demonstrate the feasibility, a VCAM1-targeted and ultrasound (US)-activated liposome (LPCOTML) loaded with a reactive-oxygen-species (ROS)-responsive lipoid prodrug of oleoyl meropenem, sonosensitizer of lipoid Ce6, and perfluoropentane is developed. LPCOTML can recognize the receptors on vascular cells, and initiate receptor-mediated transcytosis for transendothelial transport into the BSSI periphery. LPCOTML subsequently transforms from nanoparticle into microbubble via liquid-gas phase transition under US irradiation, triggering strong ultrasonic cavitation to blow up the EPS and deeply penetrate the biofilms. The sonosensitizer Ce6 induces ROS production under US irradiation and triggers the release of meropenem to induce potent antibacterial effect in a BSSI model. This study presents an effective strategy to tackle the biological barriers in BSSI via combining receptor-mediated transcytosis and ultrasonic cavitation.

The battle against dental caries: defeating biofilm formed by bacterial isolates using vanillin and plant essential oils: in vitro and ex vivo approaches

BackgroundInfections caused by biofilm-forming bacteria have significantly linked to dental plaque and caries. The aim of this study is to assess efficacy of some natural compounds in inhibition and eradication of biofilm formed by bacterial isolates from dental infections.ResultsBacterial isolates were recovered from dental plaque/caries and identified using standard microbiological tests and 16S rDNA sequencing. The isolated bacterial strains include Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Klebsiella pneumoniae, and Escherichia coli. The antibiotic susceptibility was determined by disk diffusion method and revealed that the majority of isolates showed high antibiotic resistance, and 61% of isolates were found to be multidrug resistant. The biofilm formation capacity of isolates was investigated using microtiter plate assay. Among the 77 bacterial isolates, seventeen showed moderate biofilm formation capacity, twenty-two showed near-moderate, thirty-four had weak biofilm-forming capacity, and four were non-biofilm producers. The antibiofilm activity of tested compounds (rose and jasmine oils, propolis, vanillin, and vinegar) was evaluated against isolates with highest biofilm-forming capacity. The in vitro antibiofilm ability of tested substances were investigated alone or in combination with each other to evaluate their ability to prevent biofilm formation or destroy preformed single-/multispecies biofilms. Finally, antibiofilm ability of tested combination was evaluated ex vivo on natural teeth. Our results showed that vanillin in combination with rose or jasmine oils showed promising biofilm inhibition and biofilm eradication activities in both the in vitro and ex vivo models.ConclusionsDental plaque and caries can be successfully prevented using combination of vanillin with rose or jasmine oils, and these compounds can be incorporated in new anticaries dental formulations.

Biofilm Microenvironment-Sensitive Anti-Virulent and Immunomodulatory Nano-on-Nanodroplets to Combat Refractory Biofilm Infection Through Toxin Neutralization and Phagocytosis.

Biofilm-associated wound infection is principally perceived as the bacterial defense mechanism that hinders antibiotic penetration, causes toxin impairment, and suppresses the immunological responses of the host immune system. Several antibiofilm agents have been developed, but the least of these agents can simultaneously cornerstone on the biofilm-associated immunosuppression and bacterial toxin-induced cellular dysfunction. Inspired by the fusogenic property of nanodroplets and immunomodulatory functions of metal nanoparticles, biofilm targeted anti-virulent immunomodulatory cationic nanoparticle shelled nanodroplets (C-AgND) is fabricated to completely disintegrate and eradicate the Staphylococcus aureus (S. aureus) biofilm. The specific binding of C-AgND neutralizes the negatively charged EPS layer, causing their destabilization followed by penetration of the nanoformulation into the biofilm matrix, killing the persister cells. Consequently, C-AgND eliminates the virulence property of the S. aureus biofilm through α-hemolysin neutralization. C-AgND promotes a strong immunomodulatory effect by polarizing macrophages into their M1 phenotype to induce phagocytosis of the disintegrated biofilm-released residual cells, rejuvenating the host's innate immune responses for the complete eradication of the biofilm. Moreover, the ex vivo skin wound infection model illustrates an excellent biofilm eradication efficacy of C-AgND in comparison to the commercial ones, rendering them to be a promising replacement of existing antibiofilm agents in clinical application.

Bacterial inhibition and biofilm eradication ability of low-toxic deep eutectic solvents prepared from lactic acid and quaternary ammonium compounds

In the present communication, the preparation of deep eutectic solvents (DESs) based on an aqueous solution of lactic acid (LA) and two different quaternary ammonium compounds, choline chloride (ChCl) and tetraethylammonium chloride (TEAC), is proposed for the application as an antibacterial agent. The antibacterial and cytotoxic properties of the DESs obtained were studied and found to be highly effective in inhibiting both Gram-positive and Gram-negative bacteria and eradicating bacterial biofilms. Moreover, the DESs obtained exhibited reduced cytotoxicity towards soft tissue cells compared to the aqueous LA solution. The excellent antibacterial properties and low cytotoxicity of the DESs prepared make them a promising candidate for the development of novel antimicrobial agents or antibacterial eutectogels for delivery systems and tissue engineering applications.

Biomimetic Electrodynamic Metal-Organic Framework Nanosponges for Augmented Treatment of Biofilm Infections.

Electrodynamic therapy (EDT) is a promising alternative approach for antibacterial therapy, as reactive oxygen species (ROS) are produced efficiently in response to an electric field without relying on endogenous H2O2 and O2. However, the inherent toxicity of metallic catalysts and numerous bacterial toxins during the therapeutic process still hinder its development. Herein, biomimetic metal-organic (MOF@EV) nanosponges composed of ginger-derived extracellular vesicles (EVs), and electrodynamic metal-organic frameworks (MOFs) are developed for the eradication of bacterial infections and the absorption of toxins. The prolonged circulation time of MOF@EV in vivo facilitates their accumulation at infection sites. More interestingly, MOF@EV can behave as nanosponges and effectively prevent host cells from binding to bacterial toxins, thereby reducing damage to cells. Subsequently, the MOF@EV nanosponges are discovered to work as electro-sensitizers, which is confirmed through both theoretical calculation and experimental verification. As a result, ROS is continuously produced under the electric field to achieve effective EDT-mediated bacterial eradication. Meanwhile, the treatment process of MOF@EV in vivo is visualized in mice infected with luciferase-expressing Staphylococcus aureus (S. aureus), and excellent biofilm eradication capacity and detoxification efficiency are demonstrated in a subcutaneous abscess model. This work provides a promising strategy for the treatment of bacterial infections.

Unveiling the impact of antibiotic stress on biofilm formation and expression of toxin-antitoxin system genes in Clostridium difficile clinical isolates.

The study investigates how antibiotics affect biofilm formation and toxin gene expression in Clostridium difficile, which is essential for its survival and persistence. The study confirmed 25 strains of C. difficile and assessed biofilm formation. The MIC of metronidazole and vancomycin was determined through agar dilution, and the impact of sub-MIC levels on biofilm formation and eradication was investigated. Additionally, Real-time PCR was used to analyze the expression levels of target genes related to antibiotic treatment. We found that certain genes, such as the ImmA/IrrE system, were associated with increased biofilm formation in isolates. Sub-MIC antibiotic levels influenced gene expression related to biofilm activities, particularly emphasizing the importance of toxin-antitoxin systems. The results suggest that antibiotics at sub-MIC levels may play a signaling role in promoting biofilm formation and gene expression in C. difficile. Our study suggests that toxin and antitoxin genes may impact C. difficile biofilm formation, while antibiotics could signal biofilm strengthening and gene expression increase.

Activity of polymyxin B combined with cefepime-avibactam against the biofilms of polymyxin B-resistant Pseudomonas aeruginosa and Klebsiella pneumoniae in in vitro and in vivo models

Bacterial biofilms, often forming on medical devices, can lead to treatment failure due to their increased antimicrobial resistance. Cefepime-avibactam (CFP-AVI) exhibits potent activities against Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumoniae (K. pneumoniae) when used with polymyxin B (PMB). However, its efficacy in biofilm-related infections is unknown. The present study aimed to evaluate the activity of PMB combined with CFP-AVI against the biofilms of PMB-resistant Gram-negative bacteria. Five K. pneumoniae strains and three P. aeruginosa strains known to be PMB-resistant and prone to biofilm formation were selected and evaluated. Antimicrobial susceptibility assays demonstrated that the minimal biofilm inhibitory and eradication concentrations of PMB and CFP-AVI for biofilms formed by the eight strains were significantly higher than the minimal inhibitory concentrations of the antibiotics for planktonic cells. The biofilm formation inhibition and eradication assays showed that PMB combined with CFP-AVI cannot only suppress the formation of biofilm but also effectively eradicate the preformed mature biofilms. In a modified in vitro pharmacokinetic/pharmacodynamic biofilm model, CFP-AVI monotherapy exhibited a bacteriostatic or effective activity against the biofilms of seven strains, whereas PMB monotherapy did not have any activity at 72 h. However, PMB combined with CFP-AVI demonstrated bactericidal activity against the biofilms of all strains at 72 h. In an in vivo Galleria mellonella infection model, the 7-day survival rates of larvae infected with biofilm implants of K. pneumoniae or P. aeruginosa were 0-6.7%, 40.0-63.3%, and 46.7–90.0%, respectively, for PMB alone, CFP-AVI alone, and PMB combined with CFP-AVI; the combination therapy increased the rate by 6.7–33.3% (P < 0.05, n = 6), compared to CFP-AVI monotherapy. It is concluded that PMB combined with CFP-AVI exhibits effective anti-biofilm activities against PMB-resistant K. pneumoniae and P. aeruginosa both in vitro and in vivo, and thus may be a promising therapeutic strategy to treat biofilm-related infections.

The activity of hydrolytic enzymes and antibiotics against biofilms of bacteria isolated from industrial-scale cooling towers

BackgroundCooling towers (CTs) are crucial to myriad industrial processes, supporting thermal exchange between fluids in heat exchangers using water from lakes and rivers as coolant. However, CT water can sometimes introduce microbial contaminants that adhere to and colonize various surfaces within the CT system. These microorganisms can form biofilms, significantly hindering the system’s thermal exchange efficiency. Current treatment strategies employ oxidizing biocides to prevent microbial growth. However, despite their affordability, they do not eliminate biofilms effectively and can lead to corrosive damage within the system. Herein, we aim to devise an anti-biofilm strategy utilizing hydrolytic enzymes (such as α-amylase, glucoamylase, pectin-lyase, cellulase, protease, and DNase) alongside antibiotics (including meropenem, ciprofloxacin, gentamicin, erythromycin, chloramphenicol, and ceftriaxone) to combat microbial growth and biofilm formation in cooling systems.ResultsAll enzymes reduced the development of the biofilms significantly compared to controls (p < 0.05). The polysaccharidases exhibited biomass reduction of 90%, except for pectin-lyase (80%), followed by DNAse and protease at 43% and 49%, respectively. The antibiotics reduced the biofilms of 70% of isolates in concentration of > 2 mg/mL. The minimal biofilm eradication concentration (MBEC) lower than 1 mg/mL was detected for some 7-day-old sessile isolates. The enzymes and antibiotics were also used in combination against biofilms using the modified Chequerboard method. We found six synergistic combinations, with Fractional inhibitory concentrations (FIC) < 0.5, out of the ten tested. In the presence of the enzymatic mixture, MBECs presented a significant decrease (p < 0.05), at least 4-fold for antibiotics and 32-fold for enzymes. Moreover, we characterized high molecular weight (> 12 kDa) exopolysaccharides (EPS) from biofilms of ten isolates, and glycosyl composition analysis indicated a high frequency of glucose, mannose, erythrose, arabinose, and idose across isolates EPS contrasting with rhamnose, allose, and those carbohydrates, which were detected in only one isolate.ConclusionThe synergistic approach of combining enzymes with antibiotics emerges as a highly effective and innovative strategy for anti-biofilm intervention, highlighting its potential to enhance biofilm management practices.

Enhancing Gentamicin Antibacterial Activity by Co-Encapsulation with Thymoquinone in Liposomal Formulation

Background and Purpose. Gentamicin (GEN) is a broad-spectrum antibiotic that cannot be prescribed freely because of its toxicity. Thymoquinone (THQ), a phytochemical, has antibacterial, antioxidant, and toxicity-reducing properties. However, its hydrophobicity and light sensitivity make it challenging to utilize. This incited the idea of co-encapsulating GEN and THQ in liposomes (Lipo-GEN-THQ). Method. Lipo-GEN-THQ were characterized using the zeta-potential, dynamic light scattering, Fourier transform infrared spectroscopy, and transmission electron microscope (TEM). The liposomes’ stability was evaluated under different storage and biological conditions. Lipo-GEN-THQ’s efficacy was investigated by the minimum inhibitory/bactericidal concentrations (MICs-MBCs), time–kill curves, and antibiofilm and antiadhesion assays. Bacterial interactions with the empty and GEN-THQ-loaded liposomes were evaluated using TEM. Results. The Lipo-GEN-THQ were spherical, monodispersed, and negatively charged. The Lipo-GEN-THQ were relatively stable and released GEN sustainably over 24 h. The liposomes exhibited significantly higher antibacterial activity than free GEN, as evidenced by the four-fold lower MIC and biofilm eradication in resistant E. coli strain (EC-219). TEM images display how the empty liposomes fused closely to the tested bacteria and how the loaded liposomes caused ultrastructure damage and intracellular component release. An antiadhesion assay showed that the Lipo-GEN-THQ and free GEN (0.125 mg/L) similarly inhibited Escherichia coli (EC-157) adhesion to the A549 cells (68% vs. 64%). Conclusions. The Lipo-THQ-GEN enhanced GEN by combining it with THQ within the liposomes, reducing the effective dose. The reduction in the GEN dose after adding THQ may indirectly reduce the toxicity and aid in developing an enhanced and safer form of GEN.

Antimicrobial and antibiotic-potentiating effect of calcium peroxide nanoparticles on oral bacterial biofilms

Bacterial biofilms represent a prominent biological barrier against physical and chemical attacks. Disturbing the anaerobic microenvironment within biofilms by co-delivery of oxygen appears as a promising strategy to enhance the activity of an antibiotic. Here, we report the effect of oxygen-producing calcium peroxide nanoparticles (CaO2 NP) in combination with tobramycin sulfate (Tob). On Pseudomonas aeruginosa PAO1 biofilms in vitro, the additive effect of CaO2 NP towards Tob activity enhanced biofilm eradication by 2 log compared to Tob alone. For natural biofilms grown in the oral cavity of human volunteers in situ, treatment by CaO2 NP alone slightly increased the fraction of dead bacteria from 44% in various controls, including Tob alone, to 57%. However, the combination of CaO2 NP with Tob further increased the fraction of dead bacteria to 69%. These data confirm the intrinsic antimicrobial and antibiotic-potentiating effect of CaO2 NP also in a clinically relevant setting.

PH‐sensitive size/surface charge‐adaptive quaternary ammonium salt copolymer micelles for antibiofilm activity against Staphylococcus aureus

AbstractThe low penetration of antibacterial materials within biofilms results in a 1000‐fold decrease in bactericidal efficiency, complicating the complete removal of biofilms and potentially leading to persistent and recurrent bacterial infections that significantly impact human health. In this study, we present a multifunctional pH‐responsive antibacterial material based on random copolymers poly(dimethylaminoethyl methacrylate decyl ammonium bromide‐co‐polyethylene glycol methacrylate) copolymer (PQACs10‐co‐PEGMA10). The PQACs10‐co‐PEGMA10 copolymers could self‐assemble into micelles in selective solvent water. With the stealth function of polyethylene glycol (PEG), the PQACs10‐co‐PEGMA10 micelles can rapidly penetrate biofilms in a physiological environment and exhibit excellent antibacterial activity by exposing the quaternary ammonium salt (QACs) in an acidic microenvironment to eliminate biofilm. Furthermore, PQACs10‐co‐PEGMA10 micelles were applied as coatings using a dropwise method. The PEG chain formed hydration layer and the QACs chain for sterilization can hinders bacterial adhesion and proliferation, thereby preventing biofilm formation. The results show that the minimal inhibit concentration values and minimum biofilm eradication concentrations of the PQACs10‐co‐PEGMA10 micelles against Gram‐positive Staphylococcus aureus were 64 and 128 μg/mL, respectively. The antifouling and antibacterial rates of micelle coating against S. aureus were more than 99.99%. Taken together, the pH‐responsive PQACs10‐co‐PEGMA10 micelles demonstrate a good ability to clear and prevent biofilms, holding promise for complete biofilm removal and a reduction in biofilm‐related infections.

Disrupting Mycobacterium smegmatis biofilm using enzyme-immobilized rifampicin loaded silk fibroin nanoparticles for dual anti-bacterial and anti-biofilm action

Biofilm formation is a major challenge in the treatment of tuberculosis, leading to poor treatment outcomes and latent infections. The complex and dense extracellular polymeric substances (EPS) of the biofilm provides safe harbour for bacterium enabling persistence against anti-TB antibiotics. In this study, we demonstrated that rifampicin-encapsulated silk fibroin nanoparticles immobilized with antibiofilm enzymes can disrupt the Mycobacterium smegmatis biofilm and facilitate the anti-bacterial action of Rifampicin (RIF). The EPS of M.smegmatis biofilm predominantly comprised of lipids (48.8 ± 1.32 %) and carbohydrates (34.8 ± 4.70 %), similar to tuberculosis biofilms. Pre-formed biofilm eradication screening revealed that hydrolytic enzymes such as β-Glucosidase, Glucose oxidase, ɑ-Amylase, Acylase, and Phytase can exhibit biofilm eradication of M.smegmatis biofilms. The enzyme-mediated biofilm disruption was associated with a decrease in hydrophobicity of biofilm surfaces. Treatment with β-glucosidase and Phytase demonstrated a putative biofilm eradication by reducing the total carbohydrates and lipid composition without causing any significant bactericidal activity. Further, Phytase (250 μg/ml) and β-Glucosidase (112.5 ± 17.6 μg/ml) conjugated rifampicin-loaded silk fibroin nanoparticles (R-SFNs) exhibited an enhanced anti-bacterial activity against pre-formed M.smegmatis biofilms, compared to free rifampicin (32.5±7 μg/ml). Notably, treatment with β-glucosidase, Phytase and ɑ-amylase immobilized SFNs decreased the biofilm thickness by ∼98.84 % at 6h, compared to control. Thus, the study highlights that coupling anti-mycobacterial drugs with biofilm-eradicating enzymes such as amylase, phytase or β-glucosidase can be a potential strategy to improve the TB therapeutic outcomes.

Valorization of oil refinery by-products: production of sophorolipids utilizing fatty acid distillates and their potential antibacterial, anti-biofilm, and antifungal activities.

Starmerella bombicola is a native yeast strain producing sophorolipids as secondary metabolites. This study explores the production, characterization, and biological activities of sophorolipids and investigates the antimicrobial, anti-biofilm, and antifungal properties of sophorolipids produced from oil refinery wastes by the yeast Starmerella bombicola. The present work demonstrated that S. bombicola MTCC 1910 when grown in oil refinery wastes namely palm fatty acid distillates and soy fatty acid distillates enhanced the rate of sophorolipids production drastically in comparison to vegetable oil, sunflower oil used as hydrophobic feedstock. Sophorolipid yields were 18.14, 37.21, and 46.1g/L with sunflower oil, palm, and soy fatty acid distillates respectively. The crude biosurfactants were characterized using TLC, FTIR, and HPLC revealing to be acetylated sophorolipids containing both the acidic and lactonic isomeric forms. The surface lowering and emulsifying properties of the sophorolipids from refinery wastes were significantly higher than the sunflower oil-derived sophorolipids. Also, all the sophorolipids exhibited strong antibacterial properties (minimum inhibitory concentrations were between 50 and 200µgmL-1) against Salmonella typhimurium, Bacillus cereus, and Staphylococcus epidermidis and were validated with morphological analysis by Scanning electron microscopy. All the sophorolipids were potent biofilm inhibitors and eradicators (minimum biofilm inhibitory and eradication concentrations were between12.5to1000µgmL-1) for all the tested organisms. Furthermore, antifungal activities were also found to exhibit about 16-56% inhibition at 1mgmL-1 for fungal mycelial growth. Therefore, this endeavour of sophorolipids production using palm and soy fatty acid distillates not only opens up a window for the bioconversion of industrial wastes into productive biosurfactants but also concludes that sophorolipids from oil refinery wastes are potent antimicrobial, anti-biofilm, and antifungal agents, highlighting their potential in biotechnological and medical applications.

Phage-liposome nanoconjugates for orthopedic biofilm eradication

Infection by multidrug-resistant (MDR) bacteria has become one of the biggest threats to public health worldwide. One reason for the difficulty in treatment is the lack of proper delivery strategies into MDR bacterial biofilms, where the thick extracellular polymeric substance (EPS) layer impedes the penetration of antibiotics and nanoparticles. Here, we propose a novel bioactive nanoconjugate of drug-loaded liposomes and bacteriophages for targeted eradication of the MDR biofilms in orthopedic infections. Phage Sb-1, which has the ability to degrade EPS, was conjugated with antibiotic-loaded liposomes. Upon encountering the biofilm, phage Sb-1 degrades the EPS structure, thereby increasing the sensitivity of bacteria to antibiotics and allowing the antibiotics to penetrate deeply into the biofilm. As a result, effective removal of MDR bacterial biofilm was achieved with low dose of antibiotics, which was proved in this study by both in vitro and in vivo investigations. Notably, in the rat prosthetic joint infection (PJI) model, we found that the liposome-phage nanoconjugates could effectively decrease the bacterial load in the infected area and significantly promote osteomyelitis recovery. It is therefore believed that the conjugation of bacteriophage and liposomes could open new possibilities for the treatment of orthopedic infections, possibly other infections in the deep tissues.

Bacteriophage-mediated approaches for biofilm control.

Biofilms are complex microbial communities in which planktonic and dormant bacteria are enveloped in extracellular polymeric substances (EPS) such as exopolysaccharides, proteins, lipids, and DNA. These multicellular structures present resistance to conventional antimicrobial treatments, including antibiotics. The formation of biofilms raises considerable concern in healthcare settings, biofilms can exacerbate infections in patients and compromise the integrity of medical devices employed during treatment. Similarly, certain bacterial species contribute to bulking, foaming, and biofilm development in water environments such as wastewater treatment plants, water reservoirs, and aquaculture facilities. Additionally, food production facilities provide ideal conditions for establishing bacterial biofilms, which can serve as reservoirs for foodborne pathogens. Efforts to combat antibiotic resistance involve exploring various strategies, including bacteriophage therapy. Research has been conducted on the effects of phages and their individual proteins to assess their potential for biofilm removal. However, challenges persist, prompting the examination of refined approaches such as drug-phage combination therapies, phage cocktails, and genetically modified phages for clinical applications. This review aims to highlight the progress regarding bacteriophage-based approaches for biofilm eradication in different settings.

Antimicrobial and antibiofilm effect of promethazine on bacterial isolates from canine otitis externa: an in vitro study

Otitis externa is an inflammatory disease of the external ear canal of complex and multifactorial etiology associated with recurrent bacterial infection. This study aimed to assess the antimicrobial and antibiofilm activity of promethazine against bacterial isolates from dogs with otitis externa, as well as the effect of this compound on the dynamics of biofilm formation over 120 h. Planktonic bacterial susceptibility to promethazine was evaluated to determine the minimum inhibitory concentrations (MIC). The minimum biofilm eradication concentration (MBEC) was also determined by broth microdilution. To evaluate the effect on biofilm growth, promethazine was tested at three concentrations MIC, MIC/2 and MIC/8, with daily readings at 48, 72, 96 and 120 h. The MICs of promethazine ranged from 48.83 to 781.25 μg mL−1. Promethazine significantly (P < 0.05) reduced mature biofilm biomass, with MBECs ranging from 48.8 to 6250 μg mL−1 and reduced (P < 0.01) biofilm formation for up to the 120-h, at concentrations corresponding to the MIC obtained against each isolate. Promethazine was effective against microorganisms associated with canine otitis externa. The data suggest that promethazine presents antimicrobial and antibiofilm activity and is a potential alternative to treat and prevent recurrent bacterial otitis in dogs. These results emphasize the importance of drug repurposing in veterinary otology as an alternative to reduce antimicrobial resistance.

The efficacy of antimicrobial solutions against multispecies bacterial biofilm with or without negative pressure wound therapy in an in vitro wound model.

Biofilm is the major challenge in chronic wound management. Instilling a wound cleansing solution aids in wound bed cleaning and infectious pathogen elimination. Negative pressure wound therapy (NPWT) improves the wound-healing process. This study investigated the efficacy of two antimicrobials (Vashe Wound Cleanser and Prontosan Wound Irrigation Solution) against a multispecies bacterial biofilm with or without NPWT in an in vitro wound model. A mixed multispecies biofilm containing Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pyogenes, and Acinetobacter baumannii was developed and verified by scanning electron microscopy and fluorescent in situ hybridization. The efficacy of Vashe and Prontosan against multispecies biofilm with or without NPWT was evaluated by colony-forming unit (cfu) of each species and total bacterial number, and visually confirmed by live/dead stain and confocal microscopy. Prontosan reduced biofilm cell numbers significantly: 6 instils over 24 h resulting in 3.86 ± 0.14 cfu log10 reduction without NPWT and 4.75 ± 0.13 cfu log10 reduction combined with NPWT (P < 0.01) and 12 instils over 48 h resulting in 5.24 ± 0.11 cfu log10 reduction without NPWT and biofilm eradication with NPWT (P < 0.001). NPWT alone or combined with Vashe failed to reduce multispecies biofilm numbers significantly over 24 or 48 h. Prontosan significantly reduced biofilm cell numbers, with better efficacy over 48 than 24 h, emphasizing the necessity for persistent and robust treatment. NPWT enhanced the effectiveness of Prontosan instillation. However, NPWT alone or combined with Vashe showed limited efficacy and difficulty when combating the multispecies biofilm in vitro.

Synovial vancomycin and meropenem concentrations in periprosthetic joint infection treated by single-stage revision combined with intra-articular infusion.

We aimed to determine the concentrations of synovial vancomycin and meropenem in patients treated by single-stage revision combined with intra-articular infusion following periprosthetic joint infection (PJI), thereby validating this drug delivery approach. We included 14 patients with PJI as noted in their medical records between November 2021 and August 2022, comprising eight hip and seven knee joint infections, with one patient experiencing bilateral knee infections. The patients underwent single-stage revision surgery, followed by intra-articular infusion of vancomycin and meropenem (50,000 µg/ml). Synovial fluid samples were collected to assess antibiotic concentrations using high-performance liquid chromatography. The peak concentrations of vancomycin and meropenem in the joint cavity were observed at one hour post-injection, with mean values of 14,933.9 µg/ml (SD 10,176.3) and 5,819.1 µg/ml (SD 6,029.8), respectively. The trough concentrations at 24 hours were 5,495.0 µg/ml (SD 2,360.5) for vancomycin and 186.4 µg/ml (SD 254.3) for meropenem. The half-life of vancomycin was 6 hours, while that of meropenem ranged between 2 and 3.5 hours. No significant adverse events related to the antibiotic administration were observed. This method can achieve sustained high antibiotic concentrations within the joint space, exceeding the reported minimum biofilm eradication concentration. Our study highlights the remarkable effectiveness of intra-articular antibiotic infusion in delivering high intra-articular concentrations of antibiotics. The method provided sustained high antibiotic concentrations within the joint cavity, and no severe side-effects were observed. These findings offer evidence to improve clinical treatment strategies. However, further validation is required through studies with larger sample sizes and higher levels of evidence.