Tip extension and simultaneous multiple fission in a filamentous bacterium.

Organisms display an immense variety of shapes, sizes, and reproductive strategies. At microscopic scales, bacterial cell morphology and growth dynamics are adaptive traits that influence the spatial organization of microbial communities. In one such community-the human dental plaque biofilm-a network of filamentous Corynebacterium matruchotii cells forms the core of bacterial consortia known as hedgehogs, but the processes that generate these structures are unclear. Here, using live-cell time-lapse microscopy and fluorescent D-amino acids to track peptidoglycan biosynthesis, we report an extraordinary example of simultaneous multiple division within the domain Bacteria. We show that C. matruchotii cells elongate at one pole through tip extension, similar to the growth strategy of soil-dwelling Streptomyces bacteria. Filaments elongate rapidly, at rates more than five times greater than other closely related bacterial species. Following elongation, many septa form simultaneously, and each cell divides into 3 to 14 daughter cells, depending on the length of the mother filament. The daughter cells then nucleate outgrowth of new thinner vegetative filaments, generating the classic "whip handle" morphology of this taxon. Our results expand the known diversity of bacterial cell cycles and help explain how this filamentous bacterium can compete for space, access nutrients, and form important interspecies interactions within dental plaque.

Amino Acid-Conjugated Polymer-Silver Bromide Nanocomposites for Eradicating Polymicrobial Biofilms and Treating Burn Wound Infections.

The rise in antimicrobial resistance, the increasing occurrence of bacterial, and fungal infections, and the challenges posed by polymicrobial biofilms necessitate the exploration of innovative therapeutic strategies. Silver-based antimicrobials have garnered attention for their broad-spectrum activity and multimodal mechanisms of action. However, their effectiveness against single-species or polymicrobial biofilms remains limited. In this study, we present the fabrication of polymer-silver bromide nanocomposites using amino acid conjugated polymers (ACPs) through a green and water-based in situ technique. The nanocomposite architecture facilitated prolonged and controlled release of the active components. Remarkably, the nanocomposites exhibited broad-spectrum activity against multidrug-resistant (MDR) human pathogenic bacteria (MIC = 2-16 µg/mL) and fungi (MIC = 1-8 µg/mL), while displaying no detectable toxicity to human erythrocytes (HC50 > 1024 µg/mL). In contrast to existing antimicrobials and silver-based therapies, the nanocomposite effectively eradicated bacterial, fungal, and polymicrobial biofilms, and prevented the development of microbial resistance due to their membrane-active properties. Furthermore, the lead polymer-silver bromide nanocomposite demonstrated a 99% reduction in the drug-resistant Pseudomonas aeruginosa burden in a murine model of burn wound infection, along with excellent in vivo biocompatibility.

Strategies for controlling polymicrobial biofilms: A focus on antibiofilm agents.

Polymicrobial biofilms are among the leading causes of antimicrobial treatment failure. In these biofilms, bacterial and fungal pathogens interact synergistically at the interspecies, intraspecies, and interkingdom levels. Consequently, combating polymicrobial biofilms is substantially more difficult compared to single-species biofilms due to their distinct properties and the resulting potential variation in antimicrobial drug efficiency. In recent years, there has been an increased focus on developing alternative strategies for controlling polymicrobial biofilms formed by bacterial and fungal pathogens. Current approaches for controlling polymicrobial biofilms include monotherapy (using either natural or synthetic compounds), combination treatments, and nanomaterials. Here, a comprehensive review of different types of polymicrobial interactions between pathogenic bacterial species or bacteria and fungi is provided along with a discussion of their relevance. The mechanisms of action of individual compounds, combination treatments, and nanomaterials against polymicrobial biofilms are thoroughly explored. This review provides various future perspectives that can advance the strategies used to control polymicrobial biofilms and their likely modes of action. Since the majority of research on combating polymicrobial biofilms has been conducted in vitro, it would be an essential step in performing in vivo tests to determine the clinical effectiveness of different treatments against polymicrobial biofilms.

Co-immobilization of Ciprofloxacin and Chlorhexidine as a Broad-Spectrum Antimicrobial Dual-Drug Coating for Poly(vinyl chloride) (PVC)-Based Endotracheal Tubes.

The endotracheal tube (ETT) affords support for intubated patients, but the increasing incidence of ventilator-associated pneumonia (VAP) is jeopardizing its application. ETT surfaces promote (poly)microbial colonization and biofilm formation, with a heavy burden for VAP. Devising safe, broad-spectrum antimicrobial materials to tackle the ETT bioburden is needful. Herein, we immobilized ciprofloxacin (CIP) and/or chlorhexidine (CHX), through polydopamine (pDA)-based functionalization, onto poly(vinyl chloride) (PVC) surfaces. These surfaces were characterized regarding physicochemical properties and challenged with single and polymicrobial cultures of VAP-relevant bacteria (Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis) and fungi (Candida albicans). The coatings imparted PVC surfaces with a homogeneous morphology, varied wettability, and low roughness. The antimicrobial immobilization via pDA chemistry was still evidenced by infrared spectroscopy. Coated surfaces exhibited sustained CIP/CHX release, retaining prolonged (10 days) activity. CIP/CHX-coated surfaces evidencing no A549 lung cell toxicity displayed better antibiofilm outcomes than CIP or CHX coatings, preventing bacterial attachment by 4.1-7.2 Log10 CFU/mL and modestly distressingC. albicans. Their antibiofilm effectiveness was endured toward polymicrobial consortia, substantially inhibiting the adhesion of the bacterial populations (up to 8 Log10 CFU/mL) within the consortia in dual- and even inP. aeruginosa/S. aureus/C. albicans triple-species biofilms while affecting fungal adhesion by 2.7 Log10 CFU/mL (dual consortia) and 1 Log10 CFU/mL (triple consortia). The potential of the dual-drug coating strategy in preventing triple-species adhesion and impairing bacterial viability was still strengthened by live/dead microscopy. The pDA-assisted CIP/CHX co-immobilization holds a safe and robust broad-spectrum antimicrobial coating strategy for PVC-ETTs, with the promise laying in reducing VAP incidence.

The healing effect of Pseudomonas Quinolone Signal (PQS) with co-infection of Staphylococcus aureus and Pseudomonas aeruginosa: A preclinical animal co-infection model.

BACKGROUND: Because of the rise in antibiotic resistance and the control of pathogenicity, polymicrobial bacterial biofilms exacerbate wound infections. Since bacterial quorum sensing (QS) signals can dysregulate biofilm development, they are interesting therapeutic treatments. In this study, Pseudomonas Quinolone Signal (PQS) was used to treat an animal model of a wound that had both Staphylococcus aureus and Pseudomonas aeruginosa co-infection. METHODS: S. aureus and P. aeruginosa mono- and co-infection models were developed in vitro on the L-929 cell line and in an animal model of wound infection. Moreover, PQS was extracted and purified using liquid chromatography. Then, the mono- and co-infection models were treated by PQS in vitro and in vivo. RT-PCR analysis was used to look into changes in biofilm, QS, tissue regeneration, and apoptosis genes after the treatment. RESULTS: PQS significantly disrupted established biofilm up to 90% in both in vitro and in vivo models. Moreover, a 93% reduction in the viability of S. aureus and P. aeruginosa was detected during the 10 days of treatment in comparison to control groups. In addition, the biofilm-encoding and QS-regulating genes were down-regulated to 75% in both microorganisms. Also, fewer epithelial cells died when treated with PQS compared to control groups in both mono- and co-infection groups. CONCLUSION: According to this study, PQS may facilitate wound healing by stimulating the immune system and reducing apoptosis. It seems to be a potential medication to use in conjunction with antibiotics to treat infections that are difficult to treat.

A Novel Brevinin2 HYba5 Peptide against Polymicrobial Biofilm of Staphylococcus aureus and Enterococcus faecalis.

BACKGROUND: Brevinin2 HYba5 (Peptide 29) is a novel cationic peptide identified from an endemic frog, Hydrophylax bahuvistara. Staphylococcus aureus and Enterococcus faecalis are troublesome biofilm-forming pathogens associated with nosocomial and community-acquired infections and contribute to the severity of infections associated with implanted devices and chronic wounds. Co-existence of both pathogens in biofilm mode contributes to an increased antibiotic resistance, treatment failure and hence persistent disease burden. Identifying a novel and stable, less toxic compound targeting multispecies biofilm with a lower probability of acquiring resistance in comparison to antibiotics is highly warranted. OBJECTIVE: Evaluate the activity of Brevinin2 HYba5 against S. aureus and E. faecalis mixed biofilm. METHODS: The anti-biofilm activity of peptide 29 was tested by Crystal violet assay, Confocal laser scanning Microscopy (CLSM) and MTT Assay. Cytotoxicity of the peptide was tested in RBC and L929 fibroblast cell line. Biofilm inhibitory activity of the peptide was evaluated at different temperatures, pH, serum and plasma concentrations. The antibiofilm potential of the peptide was tested against polymicrobial biofilm by Fluorescent in situ hybridisation (FISH) and plate counting on HiCromeTM UTI Agar media. RESULTS: The peptide 29 could inhibit biofilm formation of S. aureus and E. faecalis individually as well as in polymicrobial biofilm at 75 µM concentration. The peptide maintained its antibiofilm potential at different temperatures, serum and plasma concentrations. Activity of the peptide was high at acidic and neutral pH but found to get reduced towards alkaline pH. The peptide is nonhemolytic and does not exhibit significant cytotoxicity against the L929 fibroblast cell line (92.80% cell viability). CONCLUSION: The biofilm inhibition property makes peptide 29 a promising candidate for the management of S. aureus and E. faecalis biofilm, especially in catheter-associated devices to prevent the initial colonization and thus can ease the burden of pathogenic biofilm-associated infections.

Targeted Probiotics Against Bacterial-Fungal Biofilms: A New Concept Seems to Bring Us Closer to Microbiome-modulating Therapy for Inflammatory Bowel Disease.

This article describes the concept of microbiome-modulating therapy for inflammatory bowel diseases using targeted probiotics. A designed probiotic composition is discussed as an example, the targets for which are polymicrobial bacterial-fungal biofilms specific for Crohn's disease.

Efficacy of mixed diclofenac solutions against root canal biofilms.

The objective of this research was to evaluate the efficacy of diclofenac sodium solutions, with or without cetrimide (CTR) added, against polymicrobial root canal biofilms grown in dentin specimens. The study groups were: (1) 5% diclofenac sodium (DCS); (2) 2.5% DCS; (3) 2.5% DCS + 0. 2% CTR; (4) 2.5% DCS + 0.4% CTR and (5) 0.9% saline solution (SS) as the control. After 5 min of solution contact with the biofilms, the antimicrobial activity was evaluated by means of the adenosine triphosphate (ATP) assay as well as confocal laser scanning microscopy (CLSM). Microbial quantification was indicated as the percentage reduction of relative light units (RLUs) for the ATP assay, the Log10 total biovolume and the viability percentage (green cells) for CLSM. Solutions of 2.5% DCS + 0.4% CTR and 5% DCS showed the highest antimicrobial efficacy. Cetrimide increased the antibiofilm activity of diclofenac sodium against endodontic biofilms.

Combating polymicrobial biofilm: recent approaches.

The polymicrobial biofilm (PMBF) is formed when microbes from multiple species co-aggregate into an envelope made of extra polymeric substances (EPS) that keep the microbes safe from external stresses. The formation of PMBF has been linked to a variety of human infections, including cystic fibrosis, dental caries, urinary tract infections, etc. Multiple microbial species co-aggregation during an infection results in a recalcitrant biofilm formation, which is a seriously threatening phenomenon. It is challenging to treat polymicrobial biofilms since they contain multiple microbes which show drug resistance to various antibiotics/antifungals. The present study discusses various approaches by which an antibiofilm compound works. Depending on their mode of action, antibiofilm compounds can block the adhesion of cells to one another, modify membranes/walls, or disrupt quorum-sensing systems.

Differential Susceptibility of Mixed Polymicrobial Biofilms Involving Ocular Coccoid Bacteria (Staphylococcus aureus and S. epidermidis) and a Filamentous Fungus (Fusarium solani) on Ex Vivo Human Corneas.

Biofilms confer several advantages to the organisms associated with them, such as increased resistances to antibacterial and antifungal compounds compared to free living cells. Compared to monomicrobial biofilms involving a single microorganism, biofilms composed of microorganisms affiliated to bacterial and fungal kingdoms are predominant in nature. Despite the predominance of polymicrobial biofilms, and more so mixed polymicrobial biofilms, they are rarely studied. The objective of the current study is to evaluate the potential of ocular bacteria and a filamentous fungus to form monomicrobial and mixed polymicrobial biofilms on synthetic and natural substrates and to monitor their response to antibiotics. In this sense, we demonstrated that the ocular pathogens Staphylococcus aureus, S. epidermidis, and Fusarium solani form monomicrobial and mixed polymicrobial biofilms both on tissue culture polystyrene plates and on ex vivo human corneas from cadavers using confocal microscopy and scanning electron microscopy. Additionally, the mixed polymicrobial biofilms involving the above ocular bacteria and a filamentous fungus were less susceptible to different antibacterials and antifungals in relation to the corresponding control planktonic cells. Further, the MICs to the screened antibacterials and antifungals in polymicrobial biofilms involving a bacterium or a fungus was either increased, decreased, or unchanged compared to the corresponding individual bacterial or fungal biofilm. The results would be useful to the ophthalmologist to plan effective treatment regimens for the eye since these are common pathogens of the eye causing keratitis, endophthalmitis, conjunctivitis, etc.

The Coexistence of Bacterial Species Restructures Biofilm Architecture and Increases Tolerance to Antimicrobial Agents.

Chronic infections caused by polymicrobial biofilms are often difficult to treat effectively, partially due to the elevated tolerance of polymicrobial biofilms to antimicrobial treatments. It is known that interspecific interactions influence polymicrobial biofilm formation. However, the underlying role of the coexistence of bacterial species in polymicrobial biofilm formation is not fully understood. Here, we investigated the effect of the coexistence of Enterococcus faecalis, Escherichia coli O157:H7, and Salmonella enteritidis on triple-species biofilm formation. Our results demonstrated that the coexistence of these three species enhanced the biofilm biomass and led to restructuring of the biofilm into a tower-like architecture. Furthermore, the proportions of polysaccharides, proteins, and eDNAs in the extracellular matrix (ECM) composition of the triple-species biofilm were significantly changed compared to those in the E. faecalis mono-species biofilm. Finally, we analyzed the transcriptomic profile of E. faecalis in response to coexistence with E. coli and S. enteritidis in the triple-species biofilm. The results suggested that E. faecalis established dominance and restructured the triple-species biofilm by enhancing nutrient transport and biosynthesis of amino acids, upregulating central carbon metabolism, manipulating the microenvironment through "biological weapons," and activating versatile stress response regulators. Together, the results of this pilot study reveal the nature of E. faecalis-harboring triple-species biofilms with a static biofilm model and provide novel insights for further understanding interspecies interactions and the clinical treatment of polymicrobial biofilms. IMPORTANCE Bacterial biofilms possess distinct community properties that affect various aspects of our daily lives. In particular, biofilms exhibit increased tolerance to chemical disinfectants, antimicrobial agents, and host immune responses. Multispecies biofilms are undoubtedly the dominant form of biofilms in nature. Thus, there is a pressing need for more research directed at delineating the nature of multispecies biofilms and the effects of the properties on the development and survival of the biofilm community. Here, we address the effects of the coexistence of Enterococcus faecalis, Escherichia coli, and Salmonella enteritidis on triple-species biofilm formation with a static model. In combination with transcriptomic analyses, this pilot study explores the potential underlying mechanisms that lead to the dominance of E. faecalis in triple-species biofilms. Our findings provide novel insights into the nature of triple-species biofilms and indicate that the composition of multispecies biofilms should be a key consideration when determining antimicrobial treatments.

Inhibition of Candida albicans and Staphylococcus epidermidis mixed biofilm formation in a catheter disk model system treated with EtOH-EDTA solution.

Microbial colonization and the formation of biofilms on catheter surfaces pose a great risk for medical-related infections. We aimed (a) to evaluate polymicrobial biofilm formation of Candida albicans and Staphylococcus epidermidis and (b) to investigate the inhibition and effects of ethanol (EtOH) and EtOH-EDTA solutions on biofilms. Catheter disks were made and used as a substrate for biofilm formation. Varying concentrations of EtOH and EtOH-EDTA solutions were compared in deterring biofilm formation. The EtOH-EDTA solutions were further tested to remove mature and preformed biofilms. Compared to their monospecies counterparts, biofilm concentration significantly increases when C. albicans is co-cultured with S. epidermidis. Moreover, all treatments with EtOH-EDTA solution significantly lowered biofilm formation compared to EtOH alone (P ≤ 0.05). Lastly, biofilm was dramatically reduced when treated with 20%, 30%, 40%, and 50% EtOH-EDTA solutions (P ≤ 0.05). Our findings suggest that biofilms become more resilient to treatment when formed by multiple organisms. Nonetheless, treatment with EtOH-EDTA is effective against these polymicrobial biofilms.

Polymicrobial biofilms related to dental implant diseases: unravelling the critical role of extracellular biofilm matrix.

Biofilms are complex tri-dimensional structures that encase microbial cells in an extracellular matrix comprising self-produced polymeric substances. The matrix rich in extracellular polymeric substance (EPS) contributes to the unique features of biofilm lifestyle and structure, enhancing microbial accretion, biofilm virulence, and antimicrobial resistance. The role of the EPS matrix of biofilms growing on biotic surfaces, especially dental surfaces, is largely unravelled. To date, there is a lack of a broad overview of existing literature concerning the relationship between the EPS matrix and the dental implant environment and its role in implant-related infections. Here, we discuss recent advances in the critical role of the EPS matrix on biofilm growth and virulence on the dental implant surface and its effect on the etiopathogenesis and progression of implant-related infections. Similar to other biofilms associated with human diseases/conditions, EPS-enriched biofilms on implant surfaces promote microbial accumulation, microbiological shift, cross-kingdom interaction, antimicrobial resistance, biofilm virulence, and, consequently, peri-implant tissue damage. But intriguingly, the protagonism of EPS role on implant-related infections and the development of matrix-target therapeutic strategies has been neglected. Finally, we highlight the need for more in-depth analyses of polymicrobial interactions within EPS matrix and EPS-targeting technologies' rationale for disrupting the complex biofilm microenvironment with more outstanding translation to implant applications in the near future.

Caspofungin alone or combined with polymyxin B are effective against mixed biofilm of Aspergillus fumigatus and carbapenem-resistant Pseudomonas aeruginosa.

Aspergillus fumigatus and Pseudomonas aeruginosa biofilms are associated to the recalcitrant and persistent infections due to resistance to antimicrobials. Here, we evaluated the effect of antimicrobials on single and mixed biofilms of A. fumigatus and P. aeruginosa (carbapenem-resistant and susceptible strains) determining total biomass by crystal violet, cell viability by colony forming unit count, and microscopy. Polymyxin B (PMB) had the best action on P. aeruginosa biofilms inhibiting the biomass (2-4 µg/mL) and it was efficient reducing the viable bacterial cells. Amphotericin B (AMB) and caspofungin (CAS) were the best antifungal at inhibiting A. fumigatus biofilms and reducing fungal viability at concentration ≥1 and ≥ 16 µg/mL, respectively. In addition, CAS was able to significantly reduce P. aeruginosa viability in mixed biofilms. CAS combined with PMB also significantly reduced the mixed biofilm biomass and fungal and bacterial viability mainly against carbapenem-resistant bacterium. The light and fluorescence microscopy showed alterations on hyphae morphology and confirmed the increase of fungal and bacterial death cells after combined therapy of mixed biofilms. Taken together, our work showed that CAS alone and its combination with PMB showed better potential in reducing mixed biofilm biomass and fungal and bacterial viability, even for the carbapenem-resistant P. aeruginosa strain.

Exploring the Efficacy of ZB-06 Vaginal Biofilm as a Novel Treatment for Recurrent Bacterial Vaginosis.

The purpose of this research was to investigate the efficacy of ZB-06 vaginal biofilm as a novel treatment for recurrent bacterial vaginosis (BV). BV is a prevalent vaginal infection that primarily affects women of reproductive age and is linked to adverse health outcomes. Biofilm production allows bacteria to cling to the vaginal epithelium, making antibiotics harder to penetrate and treat the illness efficiently. ZB-06 is a vaginal biofilm inhibitor that may dissolve the biofilm generated by the bacteria causing BV, enhancing antibiotic therapy efficacy and lowering the risk of recurrence. The current literature on BV, biofilm formation, and the possible function of ZB-06 as a therapy option for recurrent BV is reviewed in this article. More research is needed to determine ZB-06's safety and efficacy.

Hesperetin-Between the Ability to Diminish Mono- and Polymicrobial Biofilms and Toxicity.

Hesperetin is the aglycone of citrus flavonoid hesperidin. Due to the limited information regarding hesperetin antimicrobial potential and emerging need for novel antimicrobials, we have studied its antimicrobial activity (microdilution assay), antibiofilm activity with different assays in two models (mono- and polymicrobial biofilm), and toxicity (MTT and brine shrimp lethality assays). Hesperetin inhibited growth of all Candida isolates (minimal inhibitory concentration, MIC, 0.165 mg/mL), while it's inhibitory potential towards Staphylococcus aureus was lower (MIC 4 mg/mL). Hesperetin (0.165 mg/mL) reduced ability of Candida to form biofilms and moderately reduced exopolysaccharide levels in biofilm matrix. Effect on the eradication of 24 h old C. albicans biofilms was promising at 1.320 mg/mL. Inhibition of staphylococcal biofilm formation required higher concentrations of hesperetin (<50% inhibition with MIC 4 mg/mL). Establishment of polymicrobial C. albicans-S. aureus biofilm was significantly inhibited with the lowest examined hesperetin concentration (1 mg/mL) in crystal violet and CFU assays. Hesperetin toxicity was examined towards MRC-5 fibroblasts (IC50 0.340 mg/mL) and in brine shrimp lethality assay (LC50 > 1 mg/mL). Hesperetin is efficient in combating growth and biofilm formation of Candida species. However, its antibacterial application should be further examined due to the cytotoxic effects provoked in the antibacterial concentrations.

Visualization and elimination of polymicrobial biofilms by a combination of ALA-carvacrol-blue light.

Chronic wound infections caused by multidrug-resistant (MDR) bacteria are one of the serious threats to public health due to limited therapeutic options and lengthy care. This investigation combines 5-aminolevulinic acid (ALA), blue light (BL), and phytochemical carvacrol, named ABC cocktail or trio-therapy, to efficiently eliminate wound-related MDR pathogens. Both planktonic cells and biofilms of blue light-refractory Escherichia (E.) coli and Klebsiella (K.) pneumoniae succumbed to the trio-therapy partly due to porphyrin accumulations following ALA incubation. ALA either alone or alongside carvacrol could vigorously trigger bursts of reactive oxygen species (ROS) upon blue light irradiation in K. pneumoniae, but not in mammalian cells. The robust antimicrobial activity was extended to polymicrobial biofilms composed of five MDR pathogens (Staphylococcus aureus, E. coli, K. pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa) in vitro and in vivo. Strikingly, polymicrobial biofilm in mouse wounds became readily visible in the presence of ALA owing to the increasing generation of porphyrins that exhibited bright red fluorescence in response to blue light. Thus, ALA not only enhances killing efficacy, but also helps to pinpoint the infections for guiding debridement, precise phototherapy, and timely assessment of treatment effectiveness. Featuring a broadened antimicrobial spectrum and advantages of bacterial/biofilm imaging, the trio-therapy can be used either alone or adjunctive to other wound management modalities to effectively combat MDR bacteria in wounds.

Antimicrobial Combined Action of Graphene Oxide and Light Emitting Diodes for Chronic Wound Management.

Innovative non-antibiotic compounds such as graphene oxide (GO) and light-emitting diodes (LEDs) may represent a valid strategy for managing chronic wound infections related to resistant pathogens. This study aimed to evaluate 630 nm LED and 880 nm LED ability to enhance the GO antimicrobial activity against Staphylococcus aureus- and Pseudomonas aeruginosa-resistant strains in a dual-species biofilm in the Lubbock chronic wound biofilm (LCWB) model. The effect of a 630 nm LED, alone or plus 5-aminolevulinic acid (ALAD)-mediated photodynamic therapy (PDT) (ALAD-PDT), or an 880 nm LED on the GO (50 mg/l) action was evaluated by determining the CFU/mg reductions, live/dead analysis, scanning electron microscope observation, and reactive oxygen species assay. Among the LCWBs, the best effect was obtained with GO irradiated with ALAD-PDT, with percentages of CFU/mg reduction up to 78.96% ± 0.21 and 95.17% ± 2.56 for S. aureus and P. aeruginosa, respectively. The microscope images showed a reduction in the cell number and viability when treated with GO + ALAD-PDT. In addition, increased ROS production was detected. No differences were recorded when GO was irradiated with an 880 nm LED versus GO alone. The obtained results suggest that treatment with GO irradiated with ALAD-PDT represents a valid, sustainable strategy to counteract the polymicrobial colonization of chronic wounds.

Competitiveness during Dual-Species Biofilm Formation of Fusarium oxysporum and Candida albicans and a Novel Treatment Strategy.

During an infection, a single or multispecies biofilm can develop. Infections caused by non-dermatophyte molds, such as Fusarium spp. and yeasts, such as Candida spp., are particularly difficult to treat due to the formation of a mixed biofilm of the two species. Fusarium oxysporum is responsible for approximately 20% of human fusariosis, while Candida albicans is responsible for superficial mucosal and dermal infections and for disseminated bloodstream infections with a mortality rate above 40%. This study aims to investigate the interactions between C. albicans and F. oxysporum dual-species biofilm, considering variable formation conditions. Further, the ability of the WMR peptide, a modified version of myxinidin, to eradicate the mixed biofilm when used alone or in combination with fluconazole (FLC) was tested, and the efficacy of the combination of WMR and FLC at low doses was assessed, as well as its effect on the expression of some biofilm-related adhesin and hyphal regulatory genes. Finally, in order to confirm our findings in vivo and explore the synergistic effect of the two drugs, we utilized the Galleria mellonella infection model. We concluded that C. albicans negatively affects F. oxysporum growth in mixed biofilms. Combinatorial treatment by WMR and FLC significantly reduced the biomass and viability of both species in mature mixed biofilms, and these effects coincided with the reduced expression of biofilm-related genes in both fungi. Our results were confirmed in vivo since the synergistic antifungal activity of WMR and FLC increased the survival of infected larvae and reduced tissue invasion. These findings highlight the importance of drug combinations as an alternative treatment for C. albicans and F. oxysporum mixed biofilms.

An intestinal Candida albicans model for monomicrobial and polymicrobial biofilms and effects of hydrolases and the Bgl2 ligand.

Background and Aim: Candida albicans is the most prevalent human fungal pathogen. In biofilms, C. albicans becomes more resistant to antifungal agents because of the production of an extracellular matrix (ECM) that protects the yeast cells. This study aimed to determine the effects of hydrolase enzymes and the Bgl2 ligand on monomicrobial and polymicrobial biofilms. Materials and Methods: Biofilm induction in rats was carried out using streptomycin (25 mg/kg) and gentamicin (7.5 mg/kg) administered orally once per day for 5 days. Rats were injected subcutaneously with cortisone acetate (225 mg/kg) as an immunosuppressant on day 5. In addition, rats were orally administered C. albicans for the single microbial model and a combination of C. albicans with Escherichia coli for the polymicrobial model. Following the biofilm production, the groups were treated with glucosamine (8.57 mg/kg body weight) and Achatina fulica hydrolases (1.5 mL) orally for 2 weeks. The reduction of the biofilm was measured using confocal laser scanning microscopy (CLSM). Data were analyzed using a t-test, with a significance value of 95%. Results: CLSM images revealed a strong association between C. albicans and E. coli in the polymicrobial biofilm. On the contrary, the combination treatment using glucosamine and A. fulica hydrolases reduced the ECM of the single microbial biofilm (53.58%). However, treatment effectiveness against the matrix (19.17%) was reduced in the polymicrobial model. Conclusion: There is a strong association between C. albicans and E. coli in the formation of polymicrobial biofilms. The combination of glucosamine and the A. fulica enzyme can reduce the single microbial biofilm ECM; however, it is ineffective in the polymicrobial model.