Biofilm-related Infections Research Articles

Microbial Biofilms: Applications, Clinical Consequences, and Alternative Therapies.

Biofilms are complex communities of microorganisms that grow on surfaces and are embedded in a matrix of extracellular polymeric substances. These are prevalent in various natural and man-made environments, ranging from industrial settings to medical devices, where they can have both positive and negative impacts. This review explores the diverse applications of microbial biofilms, their clinical consequences, and alternative therapies targeting these resilient structures. We have discussed beneficial applications of microbial biofilms, including their role in wastewater treatment, bioremediation, food industries, agriculture, and biotechnology. Additionally, we have highlighted the mechanisms of biofilm formation and clinical consequences of biofilms in the context of human health. We have also focused on the association of biofilms with antibiotic resistance, chronic infections, and medical device-related infections. To overcome these challenges, alternative therapeutic strategies are explored. The review examines the potential of various antimicrobial agents, such as antimicrobial peptides, quorum-sensing inhibitors, phytoextracts, and nanoparticles, in targeting biofilms. Furthermore, we highlight the future directions for research in this area and the potential of phytotherapy for the prevention and treatment of biofilm-related infections in clinical settings.

The role of microbial biofilms in the development of respiratory system complications in patients with COVID-19: A literature review

One of the complications of COVID-19 is the development of acute respiratory failure, which may require artificial ventilation using an endotracheal tube to correct hypoxaemia. However, the establishment of biofilms during intubation of patients can pose a risk of microbial growth that can cause severe complications. Therefore, the research on the microbial composition of biofilms that causes such diseases becomes an urgent issue. The purpose of the research was to analyse and summarise the data from current studies on the role of microbial biofilms and their impact on the development of respiratory system complications in patients with COVID-19. After reviewing the literature, it was determined that Staphylococcus epidermidis, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans accounted for the majority of biofilms isolated from endotracheal tubes in patients with COVID-19. The level of antimicrobial resistance among the isolated strains was almost 70%. The examination of samples from endotracheal tubes identified representatives of the lung microbiome, Prevotella spp. and some species of Streptococcus, Veillonella. However, in the research on the microbial composition of biofilms isolated from endotracheal tubes, pathogenic representatives dominated, such as Pseudomonas spp., Staphylococcus spp., Streptococcus spp., Stenotrophomonas spp., Enterobacterales, Haemophilus spp. and Actinomyces spp. Changes in the composition of the lung microbiome in patients with COVID-19 can lead to the development of severe complications accompanied by the establishment of biofilms. Microorganisms in biofilms can be a reservoir for secondary pulmonary infections, which affects the duration of mechanical ventilation and the admission of patients with COVID-19 to intensive care units. The development and implementation of effective measures for the prevention and treatment of biofilm-related infections is an important task for modern medical practice

Development of Smart Potentiometric Sensors Covered with Non-Biofouling Layer for Detection of Early Stages of Inflammatory Processes Around Joint Replacements

One of the problems occurring after the joint replacement is connected with the post-surgery infections which are caused by bacteria that form biofilms on surfaces and are referred to as biofilm-related infections (BRI). It is also worth noting that due to the bioresponse, strong pathophysiological changes in the microclimate of an affected surface occur (decrease in pH, formation of various reactive oxygen species (ROS), depletion of Fe ions, and increase in the concentration of Ca ions). In this work we have prepared a robust selective potentiometric sensor of ROS and pH sensor for the detection of pH changes caused by sterile inflammation and bacterial and fungal infections. The ROS sensor consists of a conductive polymer layer based on polythiophene with an incorporated porphyrin-metal complex that potentiometrically detects the presence of ROS (H2O2 and ClO– ions). This sensor is connected by the covalent bonds with a non-biofouling layer of poly(2-methyl-2-oxazoline), which works as a bio-compa­tibilizer. It was shown that the potentiometric sensor shows a rapid response to hydrogen peroxide, does not record any interference with bovine serum albumin as a model serum protein, and is able to fully reversibly detect ROS with a linear response within a wide range of biological relevant concentrations (from 0.05 μM to 10 μM). The sensing electrode based on polyaniline and poly(2-methyl-2-oxazoline) on a titanium alloy support was developed for the potentiometric detection of peri-implant pH changes to enable early detection of the aforementioned pathologies. The developed electrodes show the changing of pH in the range between 5 and 8 for the individual pathogenic bacteria or pathogenic yeast, with a Nernstian slope of −59.6/pH.

Tetrachloroaurate (III)–induced oxidation increases nonthermal plasma-induced aldehydes

Research on nonthermal plasma (NTP) devices first began almost five decades ago. NTP devices discharge electrons, positive ions, ultraviolet light, reactive oxygen species (ROS) and reactive nitrogen species (RNS) at near-physiological temperatures. Advances in plasma science have enabled the manipulation of ROS/RNS irradiation for medical applications. During preclinical stages and in human clinical trials, NTP promotes blood coagulation, eradication of bacterial, viral, and biofilm-related infections, wound healing, and cancer therapy. Previously, tetrachloroaurate (III) increased NTP-induced oxidative stress that was attenuated by reduced and oxidized glutathione, indicating that the presence of interactions between metal ions and biomolecules may modulate biological effects. In this study, using 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO) as a spin probe in electron paramagnetic resonance (EPR), we observed that the tetrachloroaurate-induced M4PO-X spin adduct was significantly suppressed by ascorbate and α-tocopherol, while dehydroascorbate (DHA) and Trolox were ineffective. Tetrachloroaurate-induced lipid peroxidation, which was measured by 2-thiobarbituric acid-reactive substances (TBARS) in combination with NTP exposure, was suppressed by ascorbate, α-tocopherol and Trolox, while DHA was ineffective. Furthermore, N-acetyl-l-cysteine and dithiothreitol efficiently suppressed tetrachloroaurate-induced M4PO-X spin adduct and lipid peroxidation. LC‒MS/MS analyzes identified hexanal that was significantly elevated by NTP exposure and/or tetrachloroaurate. However, 25 and 250 μM ascorbate did not significantly suppress the formation of aldehydes, such as acetaldehyde, hexanal, nonanal, nonenal, and 4‑hydroxy-2-nonenal. Further studies are warranted to elucidate the redox reactions between metal ions, including gold (III), and biomolecules to expand the possibility of NTP application in medicine and agriculture.

PROBIOTICS ABLE TO COUNTERACT BIOFILM-RELATED ORAL INFECTIONS

The potential clinical applications of probiotics are more and more widening, a growing evidence being accumulated on their efficacy in the prevention and treatment of different oral disturbances or diseases, including oral malodor, gingival inflammation, dental caries and periodontal diseases. Taking into consideration the widespread ability of microbial pathogens to generate persistent biofilm-related infections, an attractive proposal is to administer probiotics to prevent or counteract biofilm development.

Monitoring silica core@shell nanoparticle-bacterial film interactions using the multi-parametric surface plasmon resonance technique.

In a healthcare setting, biofilms are a major source of infection and difficult to eradicate once formed. Nanoparticles (NPs) can be designed to effectively penetrate biofilms to more efficiently either deliver antibiotic drugs throughout the biofilm matrix or elicit inherent antibiofilm activity. Antibacterial cerium oxide (CeO2) NPs were employed as core material and coated with a mesoporous silica shell (MSN) to generate cerium oxide coated mesoporous silica NPs (CeO2@MSN). Detailed studies of NP-biofilm interactions are required to rationally develop NP platforms to prevent biofilm-related infections. This work developed and implemented a unique label-free analysis platform for the real-time monitoring of bacterial biofilm formation and then assessed the interactions of antibacterial NPs. An analysis platform which allows bacterial biofilms to grow and develop in situ in flow within the multi-parametric surface plasmon resonance (MP-SPR) instrument was established. This enabled simultaneous monitoring and detection of biofilm growth phases, structure, and interactions between differentially charged CeO2@MSNs and bacterial biofilms. Positively charged antibacterial NPs (polyethyleneimine functionalized CeO2@MSNs) were found to be the most efficient to penetrate the biofilm. The MP-SPR analysis platform was shown to be a powerful tool for monitoring biofilm development in real-time and to analyze biofilm properties and NP-biofilm interactions.

Delving into the Mechanisms of Sponge-Associated Enterobacter against Staphylococcal Biofilms.

Staphylococci are one of the most common causes of biofilm-related infections. Such infections are hard to treat with conventional antimicrobials, which often lead to bacterial resistance, thus being associated with higher mortality rates while imposing a heavy economic burden on the healthcare system. Investigating antibiofilm strategies is an area of interest in the fight against biofilm-associated infections. Previously, a cell-free supernatant from marine-sponge-associated Enterobacter sp. inhibited staphylococcal biofilm formation and dissociated the mature biofilm. This study aimed to identify the chemical components responsible for the antibiofilm activity of Enterobacter sp. Scanning electron microscopy confirmed that the aqueous extract at the concentration of 32 μg/mL could dissociate the mature biofilm. Liquid chromatography coupled with high-resolution mass spectrometry revealed seven potential compounds in the aqueous extract, including alkaloids, macrolides, steroids, and triterpenes. This study also suggests a possible mode of action on staphylococcal biofilms and supports the potential of sponge-derived Enterobacter as a source of antibiofilm compounds.

Mechanistic Insights into the Antibiofilm Mode of Action of Ellagic Acid.

Bacterial biofilm is a major contributor to the persistence of infection and the limited efficacy of antibiotics. Antibiofilm molecules that interfere with the biofilm lifestyle offer a valuable tool in fighting bacterial pathogens. Ellagic acid (EA) is a natural polyphenol that has shown attractive antibiofilm properties. However, its precise antibiofilm mode of action remains unknown. Experimental evidence links the NADH:quinone oxidoreductase enzyme WrbA to biofilm formation, stress response, and pathogen virulence. Moreover, WrbA has demonstrated interactions with antibiofilm molecules, suggesting its role in redox and biofilm modulation. This work aims to provide mechanistic insights into the antibiofilm mode of action of EA utilizing computational studies, biophysical measurements, enzyme inhibition studies on WrbA, and biofilm and reactive oxygen species assays exploiting a WrbA-deprived mutant strain of Escherichia coli. Our research efforts led us to propose that the antibiofilm mode of action of EA stems from its ability to perturb the bacterial redox homeostasis driven by WrbA. These findings shed new light on the antibiofilm properties of EA and could lead to the development of more effective treatments for biofilm-related infections.

Inhibition of cell cycle-dependent hyphal and biofilm formation by a novel cytochalasin 19,20‑epoxycytochalasin Q in Candida albicans

Biofilm-mediated drug resistance is a key virulence factor of pathogenic microbes that cause a serious global health threat especially in immunocompromised individuals. Here, we investigated the antihyphal and antibiofilm activity of 19,20‑epoxycytochalasin Q (ECQ), a cytochalasin actin inhibitor isolated from medicinal mushroom Xylaria sp. BCC1067 against Candida albicans. Remarkably, 256 µg/ml of ECQ inhibited over 95% of C. albicans hyphal formation after 24 h-treatment. Combined ECQ and lipid-based biosurfactant effectively enhanced the antihyphal activity, lowering required ECQ concentrations. Hyphal fragmentation and reduction of biofilm biomass, shown by SEM and AFM visualization of ECQ-treated biofilms, were well corelated to the reduced metabolic activities of young and 24 h-preformed C. albicans biofilms. Induced intracellular accumulation of reactive oxygen species (ROS) also occurred in accompany with the leakage of shrunken cell membrane and defective cell wall at increasing ECQ concentrations. Transcriptomic analyses via RNA-sequencing revealed a massive change (> 1300 genes) in various biological pathways, following ECQ-treatment. Coordinated expression of genes, associated with cellular response to drugs, filamentous growth, cell adhesion, biofilm formation, cytoskeleton organization, cell division cycle, lipid and cell wall metabolisms was confirmed via qRT-PCR. Protein–protein association tool identified coupled expression between key regulators of cell division cyclin-dependent kinases (Cdc19/28) and a gamma-tubulin (Tub4). They coordinated ECQ-dependent hyphal specific gene targets of Ume6 and Tec1 during different phases of cell division. Thus, we first highlight the antihyphal and antibiofilm property of the novel antifungal agent ECQ against one of the most important life-threatening fungal pathogens by providing its key mechanistic detail in biofilm-related fungal infection.

A Photomodulable Bacteriophage-Spike Nanozyme Enables Dually Enhanced Biofilm Penetration and Bacterial Capture for Photothermal-Boosted Catalytic Therapy of MRSA Infections.

Nanozymes, featuring intrinsic biocatalytic effects and broad-spectrum antimicrobial properties, are emerging as a novel antibiotic class. However, prevailing bactericidal nanozymes face a challenging dilemma between biofilm penetration and bacterial capture capacity, significantly impeding their antibacterial efficacy. Here, this work introduces a photomodulable bactericidal nanozyme (ICG@hMnOx ), composed of a hollow virus-spiky MnOx nanozyme integrated with indocyanine green, for dually enhanced biofilm penetration and bacterial capture for photothermal-boosted catalytic therapy of bacterial infections. ICG@hMnOx demonstrates an exceptional capability to deeply penetrate biofilms, owing to its pronounced photothermal effect that disrupts the compact structure of biofilms. Simultaneously, the virus-spiky surface significantly enhances the bacterial capture capacity of ICG@hMnOx . This surface acts as a membrane-anchored generator of reactive oxygen species and a glutathione scavenger, facilitating localized photothermal-boosted catalytic bacterial disinfection. Effective treatment of methicillin-resistant Staphylococcus aureus-associated biofilm infections is achieved using ICG@hMnOx , offering an appealing strategy to overcome the longstanding trade-off between biofilm penetration and bacterial capture capacity in antibacterial nanozymes. This work presents a significant advancement in the development of nanozyme-based therapies for combating biofilm-related bacterial infections.

Real-time monitoring of biofilm growth identifies andrographolide as a potent antifungal compound eradicating Candida biofilms

Candida species cause life-threatening infections with high morbidity and mortality rates and their resistance to conventional therapy is closely linked to biofilm formation. Thus, the development of new approaches to study Candida biofilms and the identification of novel therapeutic strategies could yield improved clinical outcomes. In the current study, we have set up an impedance-based in vitro system to study Candida spp. biofilms in real-time and to evaluate their sensitivity to two conventional antifungal groups used in clinical practice - azoles and echinocandins. Both fluconazole and voriconazole were unable to inhibit biofilm formation in most strains tested, while echinocandins showed biofilm inhibitory capacity at relatively low concentrations (starting from 0.625 mg/L). However, assays performed on 24 h Candida albicans and C. glabrata biofilms revealed that micafungin and caspofungin failed to eradicate mature biofilms at all tested concentrations, evidencing that once formed, Candida spp. biofilms are extremely difficult to eliminate using currently available antifungals. We then evaluated the antifungal and anti-biofilm effect of andrographolide, a natural compound isolated from the plant Andrographis paniculata with known antibiofilm activity on Gram-positive and Gram-negative bacteria. Optical density measures, impedance evaluation, CFU counts, and electron microscopy data showed that andrographolide strongly inhibits planktonic Candida spp. growth and halts Candida spp. biofilm formation in a dose-dependent manner in all tested strains. Moreover, andrographolide was capable of eliminating mature biofilms and viable cell numbers by up to 99.9% in the C. albicans and C. glabrata strains tested, suggesting its potential as a new approach to treat multi-resistant Candida spp. biofilm-related infections.

Characterization of Pseudomonas aeruginosa l,d-Transpeptidases and Evaluation of Their Role in Peptidoglycan Adaptation to Biofilm Growth.

Peptidoglycan is an essential component of the bacterial cell envelope that sustains the turgor pressure of the cytoplasm, determines cell shape, and acts as a scaffold for the anchoring of envelope polymers such as lipoproteins. The final cross-linking step of peptidoglycan polymerization is performed by classical d,d-transpeptidases belonging to the penicillin-binding protein (PBP) family and by l,d-transpeptidases (LDTs), which are dispensable for growth in most bacterial species and whose physiological functions remain elusive. In this study, we investigated the contribution of LDTs to cell envelope synthesis in Pseudomonas aeruginosa grown in planktonic and biofilm conditions. We first assigned a function to each of the three P. aeruginosa LDTs by gene inactivation in P. aeruginosa, heterospecific gene expression in Escherichia coli, and, for one of them, direct determination of its enzymatic activity. We found that the three P. aeruginosa LDTs catalyze peptidoglycan cross-linking (LdtPae1), the anchoring of lipoprotein OprI to the peptidoglycan (LdtPae2), and the hydrolysis of the resulting peptidoglycan-OprI amide bond (LdtPae3). Construction of a phylogram revealed that LDTs performing each of these three functions in various species cannot be assigned to distinct evolutionary lineages, in contrast to what has been observed with PBPs. We showed that biofilm, but not planktonic bacteria, displayed an increase proportion of peptidoglycan cross-links formed by LdtPae1 and a greater extent of OprI anchoring to peptidoglycan, which is controlled by LdtPae2 and LdtPae3. Consistently, deletion of each of the ldt genes impaired biofilm formation and potentiated the bactericidal activity of EDTA. These results indicate that LDTs contribute to the stabilization of the bacterial cell envelope and to the adaptation of peptidoglycan metabolism to growth in biofilm. IMPORTANCE Active-site cysteine LDTs form a functionally heterologous family of enzymes that contribute to the biogenesis of the bacterial cell envelope through formation of peptidoglycan cross-links and through the dynamic anchoring of lipoproteins to peptidoglycan. Here, we report the role of three P. aeruginosa LDTs that had not been previously characterized. We show that these enzymes contribute to resistance to the bactericidal activity of EDTA and to the adaptation of cell envelope polymers to conditions that prevail in biofilms. These results indicate that LDTs should be considered putative targets in the development of drug-EDTA associations for the control of biofilm-related infections.

Metabolomic profiling of bacterial biofilm: trends, challenges, and an emerging antibiofilm target.

Biofilm-related infections substantially contribute to bacterial illnesses, with estimates indicating that at least 80% of such diseases are linked to biofilms. Biofilms exhibit unique metabolic patterns that set them apart from their planktonic counterparts, resulting in significant metabolic reprogramming during biofilm formation. Differential glycolytic enzymes suggest that central metabolic processes are markedly different in biofilms and planktonic cells. The glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is highly expressed in Staphylococcus aureus biofilm progenitors, indicating that changes in glycolysis activity play a role in biofilm development. Notably, an important consideration is a correlation between elevated cyclic di-guanylate monophosphate (c-di-GMP) activity and biofilm formation in various bacteria. C-di-GMP plays a critical role in maintaining the persistence of Pseudomonas aeruginosa biofilms by regulating alginate production, a significant biofilm matrix component. Furthermore, it has been demonstrated that S. aureus biofilm development is initiated by several tricarboxylic acid (TCA) intermediates in a FnbA-dependent manner. Finally, Glucose 6-phosphatase (G6P) boosts the phosphorylation of histidine-containing protein (HPr) by increasing the activity of HPr kinase, enhancing its interaction with CcpA, and resulting in biofilm development through polysaccharide intercellular adhesion (PIA) accumulation and icaADBC transcription. Therefore, studying the metabolic changes associated with biofilm development is crucial for understanding the complex mechanisms involved in biofilm formation and identifying potential targets for intervention. Accordingly, this review aims to provide a comprehensive overview of recent advances in metabolomic profiling of biofilms, including emerging trends, prevailing challenges, and the identification of potential targets for anti-biofilm strategies.

A guided tour through α-helical peptide antibiotics and their targets.

Nowadays, not only biologists, but also researchers from other disciplines such as chemistry, pharmacy, material sciences, or physics are working with antimicrobial peptides. This review is written for researchers and students working in or interested in the field of antimicrobial peptides - and especially those who do not have a profound biological background. To lay the ground for a thorough discussion on how AMPs act on cells, the architectures of mammalian and bacterial cell envelopes are described in detail because they are important targets of AMPs and provide the basis for their selectivity. The modes of action of α-helical AMPs (αAMPs) are not limited to different models of membrane permeabilization, but also include the disruption of intracellular processes, as well as the formation of fibrillary structures and their potential implications for antimicrobial activity. As biofilm-related infections are very difficult to treat with conventional antibiotics, they pose a major problem in the clinic. Therefore, this review also discusses the biological background of biofilm infections and the mode of actions of αAMPs against biofilms. The last chapter focusses on the design of αAMPs by providing an overview of historic milestones in αAMP design. It describes how modern αAMP design is aiming to produce peptides suitable to be applied in the clinic. Hence, the article concludes with a section on translational research discussing the prospects of αAMPs and remaining challenges on their way into the clinic.

Comparison of Staphylococcus aureus tolerance between antimicrobial blue light, levofloxacin, and rifampin.

Bacterial biofilms readily develop on all medical implants, including percutaneous osseointegrated (OI) implants. With the growing rate of antibiotic resistance, exploring alternative options for managing biofilm-related infections is necessary. Antimicrobial blue light (aBL) is a unique therapy that can potentially manage biofilm-related infections at the skin-implant interface of OI implants. Antibiotics are known to have antimicrobial efficacy disparities between the planktonic and biofilm bacterial phenotypes, but it is unknown if this characteristic also pertains to aBL. In response, we developed experiments to explore this aspect of aBL therapy. We determined minimum bactericidal concentrations (MBCs) and antibiofilm efficacies for aBL, levofloxacin, and rifampin against Staphylococcus aureus ATCC 6538 planktonic and biofilm bacteria. Using student t-tests (p < 0.05), we compared the efficacy profiles between the planktonic and biofilm states for the three independent treatments and a levofloxacin + rifampin combination. Additionally, we compared antimicrobial efficacy patterns for levofloxacin and aBL against biofilms as dosages increased. aBL had the most significant efficacy disparity between the planktonic and biofilm phenotypes (a 2.5 log10 unit difference). However, further testing against biofilms revealed that aBL had a positive correlation between increasing efficacy and exposure time, while levofloxacin encountered a plateau. While aBL efficacy was affected the most by the biofilm phenotype, its antimicrobial efficacy did not reach a maximum. We determined that phenotype is an important characteristic to consider when determining aBL parameters for treating OI implant infections. Future research would benefit from expanding these findings against clinical S. aureus isolates and other bacterial strains, as well as the safety of long aBL exposures on human cells.

Anti-Bacterial Adhesion on Abiotic and Biotic Surfaces of the Exopolysaccharide from the Marine Bacillus licheniformis B3-15

The eradication of bacterial biofilm represents a crucial strategy to prevent a clinical problem associated with microbial persistent infection. In this study we evaluated the ability of the exopolysaccharide (EPS) B3-15, produced by the marine Bacillus licheniformis B3-15, to prevent the adhesion and biofilm formation of Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213 on polystyrene and polyvinyl chloride surfaces. The EPS was added at different times (0, 2, 4 and 8 h), corresponding to the initial, reversible and irreversible attachment, and after the biofilm development (24 or 48 h). The EPS (300 µg/mL) impaired the initial phase, preventing bacterial adhesion even when added after 2 h of incubation, but had no effects on mature biofilms. Without exerting any antibiotic activity, the antibiofilm mechanisms of the EPS were related to the modification of the (i) abiotic surface properties, (ii) cell-surface charges and hydrophobicity, and iii) cell-to-cell aggregation. The addition of EPS downregulated the expression of genes (lecA and pslA of P. aeruginosa and clfA of S. aureus) involved in the bacterial adhesion. Moreover, the EPS reduced the adhesion of P. aeruginosa (five logs-scale) and S. aureus (one log) on human nasal epithelial cells. The EPS could represent a promising tool for the prevention of biofilm-related infections.

Efficacy of meropenem extended infusion vs intermittent bolus monotherapy and in combination with colistin against Pseudomonas aeruginosa biofilm

Device-related infections are difficult-to-treat due to biofilms. In this setting, optimizing the antibiotic efficacy is difficult since most PK/PD studies have been performed on planktonic cells, and therapies are limited when multidrug-resistant bacteria are involved. We aimed to analyze the PK/PD indices of meropenem predicting anti-biofilm efficacy againstmeropenem-susceptible and -resistantP. aeruginosastrains. Pharmacodynamics of meropenem dosages mimicking those of clinical practice (intermittent bolus of 2g every 8h; extended infusion of 2g over 4h every 8h), with and without colistin, were evaluated with the CDC Biofilm Reactor in vitro model for susceptible (PAO1) and extensively drug resistant (XDR-HUB3) P. aeruginosa. Efficacy was correlated with the pharmacokinetic/pharmacodynamic indices for meropenem. Concerning PAO1, both meropenem regimens were bactericidal, with higher killing for the extended infusion (∆log10 CFU/mL 54-0h=-4.66±0.93 and ∆log10 CFU/mL 54-0h=-3.4±0.41 for intermittent bolus; p<0.001). Concerning XDR-HUB3, meropenem by intermittent bolus was non-active whereas it showed bactericidal effect by extended infusion (∆log10 CFU/mL 54-0h=-3.65±0.29; p<0.001). Time above minimum inhibitory concentration (f%T>MIC) had the best correlation with efficacy for both strains. Adding colistin always improved meropenem activity and resistant-strains did not emerge. Thef%T>MIC was the PK/PD index that best correlated with the anti-biofilm efficacy of meropenem; it was better optimized when using extended infusion, allowing to recover bactericidal activity in monotherapy also against meropenem-resistantP. aeruginosa.Combining meropenemby extended infusionwith colistin offered the most effective therapy for both strains. Optimizing meropenem dosing by extended infusion should be encouraged when treating biofilm-related infections.

Nanomotors-loaded microneedle patches for the treatment of bacterial biofilm-related infections of wound

The biofilms formed by bacteria at the wound site can effectively protect the bacteria, which greatly weakens the effect of antibiotics. Herein, a microneedle patch for wound treatment is designed, which can effectively penetrate the biofilms in a physical way because of the penetration ability of the microneedles and the motion behavior of the nanomotors, and deliver bacterial quorum sensing inhibitor luteolin (Le) and nanomotors with multiple antibacterial properties within biofilms. Firstly, the nanomotors-loaded microneedle patches are prepared and characterized. The results of in vitro and in vivo experiments show that the microneedle patches have good biosafety and antibacterial properties. Among them, Le can inhibit the growth of biofilms. Further, under near-infrared (NIR) irradiation, the nanomotors loaded with photosensitizer ICG and nitric oxide (NO) donor L-arginine (L-Arg) can move in the biofilms under the double driving effect of photothermal and NO, and can give full play to the multiple anti-biological infection effects of photothermal therapy (PTT), photodynamic therapy (PDT) and NO, and finally realize the effective removal of biofilms and promote wound healing. The intervention of nanomotor technology has brought about a new therapeutic strategy for bacterial biofilm-related infection of wound.

Rectifying disorder of extracellular matrix to suppress urethral stricture by protein nanofilm-controlled drug delivery from urinary catheter

Urethral stricture secondary to urethral injury, afflicting both patients and urologists, is initiated by excessive deposition of extracellular matrix in the submucosal and periurethral tissues. Although various anti-fibrotic drugs have been applied to urethral stricture by irrigation or submucosal injection, their clinical feasibility and effectiveness are limited. Here, to target the pathological state of the extracellular matrix, we design a protein-based nanofilm-controlled drug delivery system and assemble it on the catheter. This approach, which integrates excellent anti-biofilm properties with stable and controlled drug delivery for tens of days in one step, ensures optimal efficacy and negligible side effects while preventing biofilm-related infections. In a rabbit model of urethral injury, the anti-fibrotic catheter maintains extracellular matrix homeostasis by reducing fibroblast-derived collagen production and enhancing metalloproteinase 1-induced collagen degradation, resulting in a greater improvement in lumen stenosis than other topical therapies for urethral stricture prevention. Such facilely fabricated biocompatible coating with antibacterial contamination and sustained-drug-release functionality could not only benefit populations at high risk of urethral stricture but also serve as an advanced paradigm for a range of biomedical applications.

Current therapies and challenges for the treatment of Staphylococcus aureus biofilm-related infections.

Staphylococcus aureus is a major cause of nosocomial and community-acquired infections and contributes to significant increase in morbidity and mortality especially when associated with medical devices and in biofilm form. Biofilm structure provides a pathway for the enrichment of resistant and persistent phenotypes of S. aureus leading to relapse and recurrence of infection. Minimal diffusion of antibiotics inside biofilm structure leads to heterogeneity and distinct physiological activity. Additionally, horizontal gene transfer between cells in proximity adds to the challenges associated with eradication of biofilms. This narrative review focuses on biofilm-associated infections caused by S. aureus, the impact of environmental conditions on biofilm formation, interactions inside biofilm communities, and the clinical challenges that they present. Conclusively, potential solutions, novel treatment strategies, combination therapies, and reported alternatives are discussed.