Understanding the Mechanism of Bacterial Biofilms Resistance to Antimicrobial Agents

Recent advances in the use of resveratrol against Staphylococcus aureus infections (Review)

As a notorious bacterial pathogen, Staphylococcus aureus (S. aureus) can readily induce infections in the community and hospital, causing significant morbidity and mortality. With the extensive rise of multiple resistance, conventional antibiotic therapy has rapidly become ineffective for related infections. Resveratrol is a naturally occurring polyphenolic substance that has been demonstrated to have effective antimicrobial activity against S. aureus. Resveratrol at sub-inhibitory doses can suppress the expression of virulence factors, contributing to attenuated biofilm formation, interference with quorum sensing and the inhibition of the production of toxins. As a promising efflux pump inhibitor, resveratrol enhances antibiotic susceptibility to a certain extent. In conjunction with conventional antibiotics, resveratrol displays unique synergistic effects with norfloxacin and aminoglycoside on S. aureus, yet antagonizes the lethal effects of daptomycin, oxacillin, moxifloxacin and levofloxacin. Nevertheless, given the low oral bioavailability of resveratrol, advanced formulations need to be developed to delay the rapid metabolism conversion to low or inactive conjugates. The present review discusses the antibacterial properties of resveratrol against S. aureus, in an aim to provide in-depth insight for researchers to address the challenges of antimicrobial resistance.

Combating bacterial biofilms and related drug resistance: Role of phyto-derived adjuvant and nanomaterials

The emergence of antimicrobial resistance (AMR) in clinical microbes has led to a search for novel antibiotics for combating bacterial infections. The treatment of bacterial infections becomes more challenging with the onset of biofilm formation. AMR is further accelerated by biofilm physiology and differential gene expression in bacteria with an inherent resistance to conventional antibiotics. In the search for innovative strategies to control the spread of AMR in clinical isolates, plant-derived therapeutic metabolites can be repurposed to control biofilm-associated drug resistance. Unlike antibiotics, designed to act on a single cellular process, phytochemicals can simultaneously target multiple cellular components. Furthermore, they can disrupt biofilm formation and inhibit quorum sensing, offering a comprehensive approach to combat bacterial infections. In bacterial biofilms, the first line of AMR is due to biofilms associated with the extracellular matrix, diffusion barriers, quorum sensing, and persister cells. These extracellular barriers can be overcome using phytochemical-based antibiotic adjuvants to increase the efficacy of antibiotic treatment and restrict the spread of AMR. Furthermore, phytochemicals can be used to target bacterial intracellular machinery such as DNA replication, protein synthesis, efflux pumps, and degrading enzymes. In parallel with pristine phytochemicals, phyto-derived nanomaterials have emerged as an effective means of fighting bacterial biofilms. These nanomaterials can be formulated to cross the biofilm barriers and function on cellular targets. This review focuses on the synergistic effects of phytochemicals and phyto-derived nanomaterials in controlling the progression of biofilm-related AMR. IT provides comprehensive insights into recent advancements and the underlying mechanisms of the use of phyto-derived adjuvants and nanomaterials.

Unleashing the power of polymeric nanoparticles - Creative triumph against antibiotic resistance: A review

Antibiotic resistance (ABR) poses a universal concern owing to the widespread use of antibiotics in various sectors. Nanotechnology emerges as a promising solution to combat ABR, offering targeted drug delivery, enhanced bioavailability, reduced toxicity, and stability. This comprehensive review explores concepts of antibiotic resistance, its mechanisms, and multifaceted approaches to combat ABR. The review provides an in-depth exploration of polymeric nanoparticles as advanced drug delivery systems, focusing on strategies for targeting microbial infections and contributing to the fight against ABR. Nanoparticles revolutionize antimicrobial approaches, emphasizing passive and active targeting. The role of various molecules, including small molecules, antimicrobial peptides, proteins, carbohydrates, and stimuli-responsive systems, is being explored in recent research works. The complex comprehension mechanisms of ABR and strategic use of nanotechnology present a promising avenue for advancing antimicrobial tactics, ensuring treatment efficacy, minimizing toxic effects, and mitigating development of ABR. Polymeric nanoparticles, derived from natural or synthetic polymers, are crucial in overcoming ABR. Natural polymers like chitosan and alginate exhibit inherent antibacterial properties, while synthetic polymers such as polylactic acid (PLA), polyethylene glycol (PEG), and polycaprolactone (PCL) can be engineered for specific antibacterial effects. This comprehensive study provides a valuable source of information for researchers, healthcare professionals, and policymakers engaged in the urgent quest to overcome ABR.

Sustainable treatment of combined industrial wastewater: synergistic phytoremediation with Eichhornia crassipes, Pistia stratiotes, and Arundo donax in biofilm wetlands

This study investigates the treatment of combined wastewater from Hattar Industrial Estate using Biofilm Wetlands (BW) planted with monoculture species: Eichhornia crassipes (EAC), Pistia stratiotes (WL), and Arundo donax (GR). Each species showed distinct capabilities in organic degradation, metal uptake, and pH stabilization. BW2, planted with EAC, achieved the highest total solids (TS) and total suspended solids (TSS) removal efficiencies of 66% and 65%, respectively. GR effectively reduced initial COD concentrations from 232 mg/L to 58.67 mg/L, while EAC and WL reached reductions to 72.78 mg/L and 70.67 mg/L, respectively. Overall, the plant efficiency ranking was EAC > GR > WL. These findings underscore the potential of these plant species in synergistic BW systems, highlighting their role as natural solutions for remediating complex industrial effluents. This research contributes to advancing eco-friendly wastewater treatment approaches, suggesting promising applications for sustainable practices in industrial contexts.RESEARCH HIGHLIGHTSThis research assessed the effectiveness of phytoremediation using Eichhornia crassipes, Pistia stratiotes, and Arundo donax for removing pollutants i.e. heavy metals (Cd, Pb, Ni, K, Ca, Mg, Na, Fe, Hg) nitrates, phosphates and sulfates from combined industrial wastewater of Hattar Industrial Estate Pakistan.It highlighted the potential of selected plant species' as natural treatment systems, providing crucial insights into their efficiency.Findings contribute to understanding nature-based solutions for complex industrial effluents.

Escaping the ESKAPE pathogens: A review on antibiofilm potential of nanoparticles

ESKAPE pathogens, a notorious consortium comprising Enterococcusfaecium, Staphylococcusaureus, Klebsiellapneumoniae, Acinetobacterbaumannii, Pseudomonasaeruginosa, and Enterobacter species, pose formidable challenges in healthcare settings due to their multidrug-resistant nature. The increasing global cases of antimicrobial-resistant ESKAPE pathogens are closely related to their remarkable ability to form biofilms. Thus, understanding the unique mechanisms of antimicrobial resistance of ESKAPE pathogens and the innate resilience of biofilms against traditional antimicrobial agents is important for developing innovative strategies to establish effective control methods against them. This review offers a thorough analysis of biofilm dynamics, with a focus on the general mechanisms of biofilm formation, the significant contribution of persister cells in the resistance mechanisms, and the recurrence of biofilms in comparison to planktonic cells. Additionally, this review highlights the potential strategies of nanoparticles for managing biofilms in the ESKAPE group of pathogens. Nanoparticles, with their unique physicochemical properties, provide promising opportunities for disrupting biofilm structures and improving antimicrobial effectiveness. The review has explored interactions between nanoparticles and biofilms, covering a range of nanoparticle types such as metal, metal-oxide, surface-modified, and functionalized nanoparticles, along with organic nanoparticles and nanomaterials. The additional focus of this review also encompasses green synthesis techniques of nanoparticles that involve plant extract and supernatants from bacterial and fungal cultures as reducing agents. Furthermore, the use of nanocomposites and nano emulsions in biofilm management of ESKAPE is also discussed. To conclude, the review addresses the current obstacles and future outlooks in nanoparticle-based biofilm management, stressing the necessity for further research and development to fully exploit the potential of nanoparticles in addressing biofilm-related challenges.

Advances in ionic liquid-based antimicrobial wound healing platforms

Wound infections, marked by the proliferation of microorganisms at surgical sites, necessitate the development of innovative wound dressings with potent bactericidal properties to curb microbial growth and prevent bacterial infiltration. This study explores the recent strides in utilizing ionic liquid-based polymers as highly promising antimicrobial agents for advanced wound healing applications. Specifically, cationic polymers containing quaternary ammonium, imidazolium, guanidinium, pyridinium, triazolium, or phosphonium groups have emerged as exceptionally effective antimicrobial compounds. Their mechanism of action involves disrupting bacterial membranes, thereby preventing the development of resistance and minimizing toxicity to mammalian cells. This comprehensive review not only elucidates the intricate dynamics of the skin's immune response and the various stages of wound healing but also delves into the synthesis methodologies of ionic liquid-based polymers. By spotlighting the practical applications of antimicrobial wound dressings, particularly those incorporating ionic liquid-based materials, this review aims to lay the groundwork for future research endeavors in this burgeoning field. Through a nuanced examination of these advancements, this article seeks to contribute to the ongoing progress in developing cutting-edge wound healing platforms that can effectively address the challenges posed by microbial infections in surgical wounds.

Micron-scale topographies affect phagocytosis of bacterial cells on polydimethylsiloxane surfaces

Many medical devices implanted in patients to mitigate diseases and medical conditions have different types of topographic features. While appropriate textures can promote the integration of host cells and reduce scar tissue formation, some textured implants with inappropriate topographies have been associated with inflammation, bacterial colonization, or even malignant complications. To better understand how surface topography affects host immune response to colonizing bacteria, a protocol was developed to investigate phagocytosis of bacterial cells attached on polydimethylsiloxane (PDMS) surfaces with different square-shaped recessive patterns. The interaction between activated RAW 264.7 macrophages and Escherichia coli in recessive wells was visualized in 3D using multiple fluorescent markers. The results revealed that there is a threshold dimension of topography, below which phagocytosis of attached bacterial cells is significantly impeded. Specifically, under our experimental condition, up to 100-fold reduction in phagocytosis was observed in square-shaped patterns with 5 µm side length and 10 µm depth compared to the flat control and patterns with 10 µm or longer side length. The spacing between wells also showed significant effects; e.g., phagocytosis in the wells further decreased when spacing increased to 50 µm. These results are helpful for understanding how undesired topographies may contribute to bacterial colonization and thus infection and other associated complications. STATEMENT OF SIGNIFICANCE: Surface topography plays an important role in bacteria-material infections and thus the safety of implantable medical devices. Undesired topographic features can cause biofilm formation and related complications. However, how surface topography affects the capability of host immune cells to clear colonizing bacteria is not well understood. In this study, the interaction between macrophage RAW264.7 and colonizing E. coli cells on polydimethylsiloxane (PDMS) with recessive features is investigated. It was discovered that the size of recessive features and the spacing between these features have significant effects on phagocytosis of bacteria by macrophages. These new results are helpful for understanding the complex interaction among host cells, bacteria, and implanted biomaterials, which will help guide the rational design of safer medical devices.

Essential oils of Eugenia spp. (myrtaceae) show in vitro antibacterial activity against Staphylococcus aureus isolates from bovine mastitis

Bovine mastitis, an inflammation of the mammary glands, is mainly caused by bacteria such as Staphylococcus aureus. While antibiotics are the primary treatment for this disease, their effectiveness is often diminished due to resistant strains and biofilm formation, creating the need for safer and more efficient therapies. Plant-based oil therapies, particularly those derived from the genus Eugenia, are gaining popularity due to their pharmacological potential and historical use. In this study, we evaluated the antibacterial, antibiofilm, and synergistic potential of essential oils (EOs) from four species of the genus Eugenia (E. brejoensis, E. gracillima, E. pohliana, and E. stictopetala) against S. aureus isolates from bovine mastitis. The EO of E. stictopetala was obtained by hydrodistillation, and its composition was analyzed using gas chromatography coupled with mass spectrometry. The experiment employed seven clinical isolates from mastitis and two control strains: ATCC 33591 (methicillin-resistant S. aureus - MRSA) and ATCC 25923 (methicillin-susceptible and biofilm producer). A broth microdilution assay was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the EOs and oxacillin. The EO of E. stictopetala contained (E)-caryophyllene (18.01%), β-pinene (8.84%), (E)-nerolidol (8.24%), and α-humulene (6.14%) as major compounds. In the MIC assay, all essential oils showed bactericidal and bacteriostatic effects, especially the species E. brejoensis and E. pohliana, which had MICs ranging from 64 to 256 µg/mL. Regarding the antibiofilm effect, all essential oils were capable of interfering with biofilm formation at subinhibitory concentrations of ½ and ¼ of the MIC. However, they did not significantly affect pre-established biofilms. Additionally, a synergistic interaction was detected between the EOs and oxacillin, with a reduction of 75-93.75% in the antimicrobial MIC. Molecular docking studies indicated that the phytochemicals β-(E)-caryophyllene, (E)-nerolidol, Δ-elemene, and α-cadinol present in the EOs formed more stable complexes with penicillin-binding proteins, indicating a possible mechanism of antibacterial action. Therefore, these results show that the essential oils of Eugenia spp. are promising sources for the development of new therapeutic methods, opening new perspectives for a more effective treatment of bovine mastitis.

Dual Antimicrobial and Anticancer Activity of Membrane-Active Peptide BP52

The linear undecapeptide BP52 was previously reported to have antibacterial activity against phytopathogenic bacteria species. Due to the structural similarities to naturally occurring cationic helical antimicrobial peptides, it was speculated that this peptide could potentially target microbial pathogens and cancer cells found in mammals. Consequently, this study aims to further investigate the structural and biological properties of this peptide. Our findings indicate that BP52 exhibits strong antimicrobial and anticancer activity while displaying relatively low levels of hemolytic activity. Hence, this study suggests that BP52 could be a potential lead compound for drug discovery against infectious diseases and cancer. Besides, new insights into the relationships between the structure and the multifunctional properties of antimicrobial peptides were also explored.

Characterization and Anti-Biofilm Activity of Lytic Enterococcus Phage vB_Efs8_KEN04 against Clinical Isolates of Multidrug-Resistant Enterococcus faecalis in Kenya

Enterococcus faecalis (E. faecalis) is a growing cause of nosocomial and antibiotic-resistant infections. Treating drug-resistant E. faecalis requires novel approaches. The use of bacteriophages (phages) against multidrug-resistant (MDR) bacteria has recently garnered global attention. Biofilms play a vital role in E. faecalis pathogenesis as they enhance antibiotic resistance. Phages eliminate biofilms by producing lytic enzymes, including depolymerases. In this study, Enterococcus phage vB_Efs8_KEN04, isolated from a sewage treatment plant in Nairobi, Kenya, was tested against clinical strains of MDR E. faecalis. This phage had a broad host range against 100% (26/26) of MDR E. faecalis clinical isolates and cross-species activity against Enterococcus faecium. It was able to withstand acidic and alkaline conditions, from pH 3 to 11, as well as temperatures between -80 °C and 37 °C. It could inhibit and disrupt the biofilms of MDR E. faecalis. Its linear double-stranded DNA genome of 142,402 bp contains 238 coding sequences with a G + C content and coding gene density of 36.01% and 91.46%, respectively. Genomic analyses showed that phage vB_Efs8_KEN04 belongs to the genus Kochikohdavirus in the family Herelleviridae. It lacked antimicrobial resistance, virulence, and lysogeny genes, and its stability, broad host range, and cross-species lysis indicate strong potential for the treatment of Enterococcus infections.

Low-dose zinc oxide nanoparticles trigger the growth and biofilm formation of Pseudomonas aeruginosa: a hormetic response

INTRODUCTION

Hormesis describes an inverse dose-response relationship, whereby a high dose of a toxic compound is inhibitory, and a low dose is stimulatory. This study explores the hormetic response of low concentrations of zinc oxide nanoparticles (ZnO NPs) toward Pseudomonas aeruginosa.

METHOD

Samples of P. aeruginosa, i.e. the reference strain, ATCC 27,853, together with six strains recovered from patients with cystic fibrosis, were exposed to ten decreasing ZnO NPs doses (0.78-400 µg/mL). The ZnO NPs were manufactured from Peganum harmala using a chemical green synthesis approach, and their properties were verified utilizing X-ray diffraction and scanning electron microscopy. A microtiter plate technique was employed to investigate the impact of ZnO NPs on the growth, biofilm formation and metabolic activity of P. aeruginosa. Real-time polymerase chain reactions were performed to determine the effect of ZnO NPs on the expression of seven biofilm-encoding genes.

RESULT

The ZnO NPs demonstrated concentration-dependent bactericidal and antibiofilm efficiency at concentrations of 100-400 µg/mL. However, growth was significantly stimulated at ZnO NPs concentration of 25 µg/mL (ATCC 27853, Pa 3 and Pa 4) and at 12.5 µg/mL and 6.25 µg/mL (ATCC 27853, Pa 2, Pa 4 and Pa 5). No significant positive growth was detected at dilutions < 6.25 µg/mL. similarly, biofilm formation was stimulated at concentration of 12.5 µg/mL (ATCC 27853 and Pa 1) and at 6.25 µg/mL (Pa 4). At concentration of 12.5 µg/mL, ZnO NPs upregulated the expression of LasB ( ATCC 27853, Pa 1 and Pa 4) and LasR and LasI (ATCC 27853 and Pa 1) as well as RhII expression (ATCC 27853, Pa 2 and Pa 4).

CONCLUSION

When exposed to low ZnO NPs concentrations, P. aeruginosa behaves in a hormetic manner, undergoing positive growth and biofilm formation. These results highlight the importance of understanding the response of P. aeruginosa following exposure to low ZnO NPs concentrations.

Antimicrobial activity of metal-based nanoparticles: a mini-review

The resistance of pathogenic microorganisms to antibiotics is one of the main problems of world health. Of particular concern are multidrug-resistant (MDR) bacteria. Infections caused by these microorganisms affect the appearance of acute or chronic diseases. In this regard, modern technologies, such as nanomaterials (NMs), especially promising nanoparticles (NPs), can possess antimicrobial properties or improve the effectiveness and delivery of known antibiotics. Their diversity and characteristics, combined with surface functionalization, enable multivalent interactions with microbial biomolecules. This article presents an overview of the most current research on replacing antibiotics with NPs, including the prospects and risks involved.

Enhanced sensitivity of extracellular antibiotic resistance genes (ARGs) to environmental concentrations of antibiotic

As emerging contaminants, antibiotics are frequently present in various environments, particularly rivers, albeit often at sublethal concentrations (ng/L∼μg/L). Assessing the risk associated with these low levels, which are far below the lethal threshold for most organisms, remains challenging. In this study, using microcosms containing planktonic bacteria and biofilm, we examined how antibiotic resistance genes (ARGs) in different physical states, including intracellular ARGs (iARGs) and extracellular ARGs (eARGs) responded to these low-level antibiotics. Our findings reveal a positive correlation between sub-lethal antibiotic exposure (ranging from 0.1 to 10 μg/L) and increased prevalence (measured as ARG copies/16s rDNA) of both iARGs and eARGs in planktonic bacteria. Notably, eARGs demonstrated greater sensitivity to antibiotic exposure compared to iARGs, with a lower threshold (0.1 μg/L for eARGs versus 1 μg/L for iARGs) for abundance increase. Moreover, ARGs in biofilms demonstrates higher sensitivity to antibiotic exposure compared to planktonic bacteria. To elucidate the underlying mechanisms, we established an integrated population dynamics-pharmacokinetics-pharmacodynamics (PD-PP) model. This model indicates that the enhanced sensitivity of eARGs is primarily driven by an increased potential for plasmid release from cells under low antibiotic concentrations. Furthermore, the accumulation of antibiotic in biofilms induces a greater sensitivity of ARG compared to the planktonic bacteria. This study provides a fresh perspective on the development of antibiotic resistance and offers an innovative approach for assessing the risk of sublethal antibiotic in the environment.

Repeated Exposure of Vancomycin to Vancomycin-Susceptible Staphylococcus aureus (VSSA) Parent Emerged VISA and VRSA Strains with Enhanced Virulence Potentials

The emergence of resistance against the last-resort antibiotic vancomycin in staphylococcal infections is a serious concern for human health. Although various drug-resistant pathogens of diverse genetic backgrounds show higher virulence potential, the underlying mechanism behind this is not yet clear due to variability in their genetic dispositions. In this study, we investigated the correlation between resistance and virulence in adaptively evolved isogenic strains. The vancomycin-susceptible Staphylococcus aureus USA300 was exposed to various concentrations of vancomycin repeatedly as a mimic of the clinical regimen to obtain mutation(s)-accrued-clonally-selected (MACS) strains. The phenotypic analyses followed by expression of the representative genes responsible for virulence and resistance of MACS strains were investigated. MACS strains obtained under 2 and 8 µg/ml vancomycin, named Van2 and Van8, respectively; showed enhanced vancomycin minimal inhibitory concentrations (MIC) to 4 and 16 µg/ml, respectively. The cell adhesion and invasion of MACS strains increased in proportion to their MICs. The correlation between resistance and virulence potential was partially explained by the differential expression of genes known to be involved in both virulence and resistance in MACS strains compared to parent S. aureus USA300. Repeated treatment of vancomycin against vancomycin-susceptible S. aureus (VSSA) leads to the emergence of vancomycin-resistant strains with variable levels of enhanced virulence potentials.

Study of the Resistance of Staphylococcus aureus Biofilm, Biofilm-Detached Cells, and Planktonic Cells to Microencapsulated Carvacrol Used Alone or Combined with Low-pH Treatment

Microbial biofilms pose severe problems in the medical field and food industry, as they are the cause of many serious infections and food-borne diseases. The extreme biofilms' resistance to conventional anti-microbial treatments presents a major challenge to their elimination. In this study, the difference in resistance between Staphylococcus aureus DSMZ 12463 biofilms, biofilm-detached cells, and planktonic cells against microcapsules containing carvacrol was assessed. The antimicrobial/antibiofilm activity of low pH disinfection medium containing the microencapsulated carvacrol was also studied. In addition, the effect of low pH on the in vitro carvacrol release from microcapsules was investigated. The minimum inhibitory concentration of microencapsulated carvacrol was 0.625 mg mL-1. The results showed that biofilms exhibited greater resistance to microencapsulated carvacrol than the biofilm-detached cells and planktonic cells. Low pH treatment alone, by hydrochloric acid addition, showed no bactericidal effect on any of the three states of S. aureus strain. However, microencapsulated carvacrol was able to significantly reduce the planktonic cells and biofilm-detached cells below the detection limit (no bacterial counts), and the biofilm by approximatively 3 log CFU mL-1. In addition, results showed that microencapsulated carvacrol combined with low pH treatment reduced biofilm by more than 5 log CFU mL-1. Thus, the use of microencapsulated carvacrol in acidic environment could be a promising approach to combat biofilms from abiotic surfaces.

Antibacterial and antibiofilm activities of selenium nanoparticles-antibiotic conjugates against anti-multidrug-resistant bacteria

The crucial demand to overcome the issue of multidrug resistance is required to refine the performance of antibiotics. Such a process can be achieved by fastening them to compatible nanoparticles to obtain effective pharmaceuticals at a low concentration. Thus, selenium nanoparticles (Se NPs) are considered biocompatible agents that are applied to prevent infections resulting from bacterial resistance to multi-antibiotics. The current evaluated the effectiveness of Se NPs and their conjugates with antibiotics such as amikacin (AK), levofloxacin (LEV), and piperacillin (PIP) against Pseudomonas aeruginosa (P. aeruginosa). In addition, the study determined the antibacterial and antibiofilm properties of Se NPs and their conjugates with LEV against urinary tract pathogens such as Staphylococcus aureus (S. aureus), Enterococcus faecalis (E. faecalis), P. aeruginosa, and Escherichia coli (E. coli). The result of minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) for eight isolates of P. aeruginosa revealed that the conjugation of Se NPs with AK, LEV, and PIP resulted in a reduction in the concentration of antibiotic-conjugated Se NPs. The concentration was found to be about 10-20 times lower than that of bare antibiotics. The MIC of the Se NPs with LEV (i.e., Se NPs:LEV) for S. aureus, E. faecalis, P. aeruginosa, and E. coli was found to be 1.4:0.5, 0.7:0.25, 22:8, and 11:4 µg/mL, respectively. The results of the half-maximal inhibitory concentration (IC50) demonstrated that Se NPs:LEV conjugate have inhibited 50 % of the mature biofilms of S. aureus, E. faecalis, P. aeruginosa, and E. coli at a concentration of 27.5 ± 10.5, 18.8 ± 3.1, 40.6 ± 10.7, and 21.6 ± 3.3 µg/mL, respectively compared to the control. It has been suggested that the antibiotic-conjugated Se NPs have great potential for biomedical applications. The conjugation of Se NPs with AK, LEV, and PIP increases the antibacterial potency against resistant pathogens at a low concentration.

Modulatory Effect of Competitive Exclusion on the Transmission of ESBL E. coli in Chickens

The extensive use of antimicrobial agents in broiler farms causes the emergence of antimicrobial resistance of E. coli producing severe economic losses to the poultry industry; therefore, monitoring the transmission of ESBL E. coli is of great significance throughout broiler farms. For this reason, we investigated the efficiency of competitive exclusion (CE) products to control the excretion and transmission of ESBL-producing E. coli in broiler chickens. Three hundred samples from 100 broiler chickens were screened for the incidence of E. coli by standard microbiological techniques. The overall isolation percentage was 39% and differentiated serologically into ten different serotypes: O158, O128, O125, O124, O91, O78, O55, O44, O2, and O1. The isolates represented absolute resistance to ampicillin, cefotaxime, and cephalexin. The effectiveness of CE (commercial probiotic product; Gro2MAX) on ESBL-producing E. coli (O78) isolate transmission and excretion was studied in vivo. The results showed that the CE product has interesting properties, making it an excellent candidate for targeted drug delivery by inhibiting bacterial growth and downregulating biofilm, adhesins, and toxin-associated genes loci. The histopathological findings demonstrated the capability of CE in repairing internal organ tissues. Our outcomes suggested that the administration of CE (probiotic products) in broiler farms could be a safe and alternative approach to control the transmission of ESBL-producing virulent E. coli in broiler chickens.

Dual roles of the conditional extracellular vesicles derived from Pseudomonas aeruginosa biofilms: Promoting and inhibiting bacterial biofilm growth

Antibiotic-resistant biofilm infections have emerged as public health concerns because of their enhanced tolerance to high-dose antibiotic treatments. The biofilm life cycle involves multiple developmental stages, which are tightly regulated by active cell-cell communication via specific extracellular signal messengers such as extracellular vesicles. This study was aimed at exploring the roles of extracellular vesicles secreted by Pseudomonas aeruginosa at different developmental stages in controlling biofilm growth. Our results show that extracellular vesicles secreted by P. aeruginosa biofilms during their exponential growth phase (G-EVs) enhance biofilm growth. In contrast, extracellular vesicles secreted by P. aeruginosa biofilms during their death/survival phase (D-EVs) can effectively inhibit/eliminate P. aeruginosa PAO1 biofilms up to 4.8-log10 CFU/cm2. The inhibition effectiveness of D-EVs against P. aeruginosa biofilms grown for 96 h improved further in the presence of 10-50 μM Fe3+ ions. Proteomic analysis suggests the inhibition involves an iron-dependent ferroptosis mechanism. This study is the first to report the functional role of bacterial extracellular vesicles in bacterial growth, which depends on the developmental stage of the parent bacteria. The finding of D-EV-activated ferroptosis-based bacterial death may have significant implications for preventing antibiotic resistance in biofilms.

Evaluating the antibacterial efficacy of a silver nanocomposite surface coating against nosocomial pathogens as an antibiofilm strategy to prevent hospital infections

Antimicrobial nanocoatings may be a means of preventing nosocomial infections, which account for significant morbidity and mortality. The role of hospital sink traps in these infections is also increasingly appreciated. We describe the preparation, material characterization and antibacterial activity of a pipe cement-based silver nanocoating applied to unplasticized polyvinyl chloride, a material widely used in wastewater plumbing. Three-dimensional surface topography imaging and scanning electron microscopy showed increased roughness in all surface finishes versus control, with grinding producing the roughest surfaces. Silver stability within nanocoatings was >99.89% in deionized water and bacteriological media seeded with bacteria. The nanocoating exhibited potent antibiofilm (99.82-100% inhibition) and antiplanktonic (99.59-99.99% killing) activity against three representative bacterial species and a microbial community recovered from hospital sink traps. Hospital sink trap microbiota were characterized by sequencing the 16S rRNA gene, revealing the presence of opportunistic pathogens from genera including Pseudomonas, Enterobacter and Clostridioides. In a benchtop model sink trap system, nanocoating antibiofilm activity against this community remained significant after 11 days but waned following 25 days. Silver nanocoated disks in real-world sink traps in two university buildings had a limited antibiofilm effect, even though in vitro experiments using microbial communities recovered from the same traps demonstrated that the nanocoating was effective, reducing biofilm formation by >99.6% and killing >98% of planktonic bacteria. We propose that conditioning films forming in the complex conditions of real-world sink traps negatively impact nanocoating performance, which may have wider relevance to development of antimicrobial nanocoatings that are not tested in the real-world.

Photoactivated riboflavin inhibits planktonic and biofilm growth of Candida albicans and non-albicans Candida species

Fungal infections caused by Candida species pose a serious threat to humankind. Antibiotics abuse and the ability of Candida species to form biofilm have escalated the emergence of drug resistance in clinical settings and hence, rendered it more difficult to treat Candida-related diseases. Lethal effects of Candida infection are often due to inefficacy of antimicrobial treatments and failure of host immune response to clear infections. Previous studies have shown that a combination of riboflavin with UVA (riboflavin/UVA) light demonstrate candidacidal activity albeit its mechanism of actions remain elusive. Thus, this study sought to investigate antifungal and antibiofilm properties by combining riboflavin with UVA against Candida albicans and non-albicans Candida species. The MIC20 for the fluconazole and riboflavin/UVA against the Candida species tested was within the range of 0.125-2 μg/mL while the SMIC50 was 32 μg/mL. Present findings indicate that the inhibitory activities exerted by riboflavin/UVA towards planktonic cells are slightly less effective as compared to controls. However, the efficacy of the combination towards Candida species biofilms showed otherwise. Inhibitory effects exerted by riboflavin/UVA towards most of the tested Candida species biofilms points towards a variation in mode of action that could make it an ideal alternative therapeutic for biofilm-related infections.

Synchronization of Mycobacterium life cycle: A possible novel mechanism of antimycobacterial drug resistance evolution and its manipulation

Mycobacterium Tuberculosis (Mtb) causing Tuberculosis (TB) is a widespread disease infecting millions of people worldwide. Additionally, emergence of drug resistant tuberculosis is a major challenge and concern in high TB burden countries. Most of the drug resistance in mycobacteria is attributed to developing acquired resistance due to spontaneous mutations or intrinsic resistance mechanisms. In this review, we emphasize on the role of bacterial cell cycle synchronization as one of the intrinsic mechanisms used by the bacteria to cope with stress response and perhaps involved in evolution of its drug resistance. The importance of cell cycle synchronization and its function in drug resistance in cancer cells, malarial and viral pathogens is well understood, but its role in bacterial pathogens has yet to be established. From the extensive literature survey, we could collect information regarding how mycobacteria use synchronization to overcome the stress response. Additionally, it has been observed that most of the microbial pathogens including mycobacteria are responsive to drugs predominantly in their logarithmic phase, while they show resistance to antibiotics when they are in the lag or stationary phase. Therefore, we speculate that Mtb might use this novel strategy wherein they regulate their cell cycle upon antibiotic pressure such that they either enter in their low metabolic phase i.e., either the lag or stationary phase to overcome the antibiotic pressure and function as persister cells. Thus, we propose that manipulating the mycobacterial drug resistance could be possible by fine-tuning its cell cycle.

Comparative proteomics analysis of biofilms and planktonic cells of Enterococcus faecalis and Staphylococcus lugdunensis with contrasting biofilm-forming ability

Biofilms make it difficult to eradicate bacterial infections through antibiotic treatments and lead to numerous complications. Previously, two periprosthetic infection-related pathogens, Enterococcus faecalis and Staphylococcus lugdunensis were reported to have relatively contrasting biofilm-forming abilities. In this study, we examined the proteomics of the two microorganisms' biofilms using LC-MS/MS. The results showed that each microbe exhibited an overall different profile for differential gene expressions between biofilm and planktonic cells as well as between each other. Of a total of 929 proteins identified in the biofilms of E. faecalis, 870 proteins were shared in biofilm and planktonic cells, and 59 proteins were found only in the biofilm. In S. lugdunensis, a total of 1125 proteins were identified, of which 1072 proteins were found in common in the biofilm and planktonic cells, and 53 proteins were present only in the biofilms. The functional analysis for the proteins identified only in the biofilms using UniProt keywords demonstrated that they were mostly assigned to membrane, transmembrane, and transmembrane helix in both microorganisms, while hydrolase and transferase were found only in E. faecalis. Protein-protein interaction analysis using STRING-db indicated that the resulting networks did not have significantly more interactions than expected. GO term analysis exhibited that the highest number of proteins were assigned to cellular process, catalytic activity, and cellular anatomical entity. KEGG pathway analysis revealed that microbial metabolism in diverse environments was notable for both microorganisms. Taken together, proteomics data discovered in this study present a unique set of biofilm-embedded proteins of each microorganism, providing useful information for diagnostic purposes and the establishment of appropriately tailored treatment strategies. Furthermore, this study has significance in discovering the target candidate molecules to control the biofilm-associated infections of E. faecalis and S. lugdunensis.

The Human Paraoxonase 2: An Optimized Procedure for Refolding and Stabilization Facilitates Enzyme Analyses and a Proteomics Approach

The human paraoxonase 2 (PON2) is the oldest member of a small family of arylesterase and lactonase enzymes, representing the first line of defense against bacterial infections and having a major role in ROS-associated diseases such as cancer, cardiovascular diseases, neurodegeneration, and diabetes. Specific Post-Translational Modifications (PTMs) clustering nearby two residues corresponding to pon2 polymorphic sites and their impact on the catalytic activity are not yet fully understood. Thus, the goal of the present study was to develop an improved PON2 purification protocol to obtain a higher amount of protein suitable for in-depth biochemical studies and biotechnological applications. To this end, we also tested several compounds to stabilize the active monomeric form of the enzyme. Storing the enzyme at 4 °C with 30 mM Threalose had the best impact on the activity, which was preserved for at least 30 days. The catalytic parameters against the substrate 3-Oxo-dodecanoyl-Homoserine Lactone (3oxoC12-HSL) and the enzyme ability to interfere with the biofilm formation of Pseudomonas aeruginosa (PAO1) were determined, showing that the obtained enzyme is well suited for downstream applications. Finally, we used the purified rPON2 to detect, by the direct molecular fishing (DMF) method, new putative PON2 interactors from soluble extracts of HeLa cells.

Poly(methylmethacrylate-co-dimethyl acrylamide)-silver nanocomposite prevents biofilm formation in medical devices

Aim: To investigate whether medical devices coated with a synthesized nanocomposite of poly(methylmethacrylate-co-dimethyl acrylamide) (PMMDMA) and silver nanoparticles (AgNPs) could improve their antibiofilm and antimicrobial activities. We also investigated the nanocomposite's safety. Materials & methods: The nanocomposite was synthesized and characterized using analytical techniques. Medical devices coated with the nanocomposite were evaluated for bacterial adhesion and hemolytic activity in vitro. Results: The nanocomposite formation was demonstrated with the incorporation of AgNPs into the polymer matrix. The nanocomposite proved to be nonhemolytic and significantly inhibited bacterial biofilm formation. Conclusion: The PMMDMA-AgNPs nanocomposite was more effective in preventing biofilm formation than PMMDMA alone and is a promising strategy for coating medical devices and reducing mortality due to hospital-acquired infections.

Polymeric Nanoparticles for Drug Delivery

The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of more sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Furthermore, polymeric nanoparticles have the ability to navigate various biological barriers to precisely target specific sites within the body, encapsulate a diverse range of therapeutic cargo and efficiently release this cargo in response to internal and external stimuli. However, despite these remarkable advantages, the presence of polymeric nanoparticles in wider clinical application is minimal. This review will provide a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles. The biological barriers affecting drug delivery will be outlined first, followed by a comprehensive description of the various nanoparticle designs and preparation methods, beginning with the polymers on which they are based. The review will meticulously explore the current performance of polymeric nanoparticles against a myriad of diseases including cancer, viral and bacterial infections, before finally evaluating the advantages and crucial challenges that will determine their wider clinical potential in the decades to come.

Blunted blades: new CRISPR-derived technologies to dissect microbial multi-drug resistance and biofilm formation

The spread of multi-drug-resistant (MDR) pathogens has rapidly outpaced the development of effective treatments. Diverse resistance mechanisms further limit the effectiveness of our best treatments, including multi-drug regimens and last line-of-defense antimicrobials. Biofilm formation is a powerful component of microbial pathogenesis, providing a scaffold for efficient colonization and shielding against anti-microbials, which further complicates drug resistance studies. Early genetic knockout tools didn't allow the study of essential genes, but clustered regularly interspaced palindromic repeat inference (CRISPRi) technologies have overcome this challenge via genetic silencing. These tools rapidly evolved to meet new demands and exploit native CRISPR systems. Modern tools range from the creation of massive CRISPRi libraries to tunable modulation of gene expression with CRISPR activation (CRISPRa). This review discusses the rapid expansion of CRISPRi/a-based technologies, their use in investigating MDR and biofilm formation, and how this drives further development of a potent tool to comprehensively examine multi-drug resistance.

A laboratory perspective on Mycobacterium abscessus biofilm culture, characterization and drug activity testing

Mycobacterium abscessus is an emerging opportunistic pathogen causing severe pulmonary infections in patients with underlying lung disease and cystic fibrosis in particular. The rising prevalence of M. abscessus infections poses an alarming threat, as the success rates of available treatment options are limited. Central to this challenge is the absence of preclinical in vitro models that accurately mimic in vivo conditions and that can reliably predict treatment outcomes in patients. M. abscessus is notorious for its association with biofilm formation within the lung. Bacteria in biofilms are more recalcitrant to antibiotic treatment compared to planktonic bacteria, which likely contributes to the lack of correlation between preclinical drug activity testing (typically performed on planktonic bacteria) and treatment outcome. In recent years, there has been a growing interest in M. abscessus biofilm research. However, the absence of standardized methods for biofilm culture, biofilm characterization and drug activity testing has led to a wide spectrum of, sometimes inconsistent, findings across various studies. Factors such as strain selection, culture medium, and incubation time hugely impact biofilm development, phenotypical characteristics and antibiotic susceptibility. Additionally, a broad range of techniques are used to study M. abscessus biofilms, including quantification of colony-forming units, crystal violet staining and fluorescence microscopy. Yet, limitations of these techniques and the selected readouts for analysis affect study outcomes. Currently, research on the activity of conventional antibiotics, such as clarithromycin and amikacin, against M. abscessus biofilms yield ambiguous results, underscoring the substantial impact of experimental conditions on drug activity assessment. Beyond traditional drug activity testing, the exploration of novel anti-biofilm compounds and the improvement of in vitro biofilm models are ongoing. In this review, we outline the laboratory models, experimental variables and techniques that are used to study M. abscessus biofilms. We elaborate on the current insights of M. abscessus biofilm characteristics and describe the present understanding of the activity of traditional antibiotics, as well as potential novel compounds, against M. abscessus biofilms. Ultimately, this work contributes to the advancement of fundamental knowledge and practical applications of accurate preclinical M. abscessus models, thereby facilitating progress towards improved therapies for M. abscessus infections.

An Overview of Frog Skin-Derived Esc Peptides: Promising Multifunctional Weapons against Pseudomonas aeruginosa-Induced Pulmonary and Ocular Surface Infections

Antimicrobial resistance is a silent pandemic harming human health, and Pseudomonas aeruginosa is the most common bacterium responsible for chronic pulmonary and eye infections. Antimicrobial peptides (AMPs) represent promising alternatives to conventional antibiotics. In this review, the in vitro/in vivo activities of the frog skin-derived AMP Esc(1-21) are shown. Esc(1-21) rapidly kills both the planktonic and sessile forms of P. aeruginosa and stimulates migration of epithelial cells, likely favoring repair of damaged tissue. However, to undertake preclinical studies, some drawbacks of AMPs (cytotoxicity, poor biostability, and limited delivery to the target site) must be overcome. For this purpose, the stereochemistry of two amino acids of Esc(1-21) was changed to obtain the diastereomer Esc(1-21)-1c, which is more stable, less cytotoxic, and more efficient in treating P. aeruginosa-induced lung and cornea infections in mouse models. Incorporation of these peptides (Esc peptides) into nanoparticles or immobilization to a medical device (contact lens) was revealed to be an effective strategy to ameliorate and/or to prolong the peptides' antimicrobial efficacy. Overall, these data make Esc peptides encouraging candidates for novel multifunctional drugs to treat lung pathology especially in patients with cystic fibrosis and eye dysfunctions, characterized by both tissue injury and bacterial infection.

Combating Antimicrobial Resistance by Employing Antimicrobial Peptides: Immunomodulators and Therapeutic Agents against Infectious Diseases

The rising prevalence of multiple-drug-resistant pathogens poses a formidable challenge to conventional antimicrobial treatments. The inability of potent antibiotics to combat these "superbugs" underscores the pressing need for alternative therapeutic agents. Antimicrobial peptides (AMPs) represent an alternative class of antibiotics. AMPs are essential immunomodulatory molecules that are found in various organisms. They play a pivotal role in managing microbial ecosystems and bolstering innate immunity by targeting and eliminating invading microorganisms. AMPs also have applications in the agriculture sector by combating animal as well as plant pathogens. AMPs can be exploited for the targeted therapy of various diseases and can also be used in drug-delivery systems. They can be used in synergy with current treatments like antibiotics and can potentially lead to a lower required dosage. AMPs also have huge potential in wound healing and regenerative medicine. Developing AMP-based strategies with improved safety, specificity, and efficacy is crucial in the battle against alarming global microbial resistance. This review will explore AMPs' increasing applicability, their mode of antimicrobial activity, and various delivery systems enhancing their stability and efficacy.

Emerging Approaches for Mitigating Biofilm-Formation-Associated Infections in Farm, Wild, and Companion Animals

The importance of addressing the problem of biofilms in farm, wild, and companion animals lies in their pervasive impact on animal health and welfare. Biofilms, as resilient communities of microorganisms, pose a persistent challenge in causing infections and complicating treatment strategies. Recognizing and understanding the importance of mitigating biofilm formation is critical to ensuring the welfare of animals in a variety of settings, from farms to the wild and companion animals. Effectively addressing this issue not only improves the overall health of individual animals, but also contributes to the broader goals of sustainable agriculture, wildlife conservation, and responsible pet ownership. This review examines the current understanding of biofilm formation in animal diseases and elucidates the complex processes involved. Recognizing the limitations of traditional antibiotic treatments, mechanisms of resistance associated with biofilms are explored. The focus is on alternative therapeutic strategies to control biofilm, with illuminating case studies providing valuable context and practical insights. In conclusion, the review highlights the importance of exploring emerging approaches to mitigate biofilm formation in animals. It consolidates existing knowledge, highlights gaps in understanding, and encourages further research to address this critical facet of animal health. The comprehensive perspective provided by this review serves as a foundation for future investigations and interventions to improve the management of biofilm-associated infections in diverse animal populations.

Antibacterial and Hemolytic Activity of Antimicrobial Hydrogels Utilizing Immobilized Antimicrobial Peptides

Antimicrobial peptides (AMPs) are viewed as potential compounds for the treatment of bacterial infections. Nevertheless, the successful translation of AMPs into clinical applications has been impeded primarily due to their low stability in biological environments and potential toxicological concerns at higher concentrations. The covalent attachment of AMPs to a material's surface has been sought to improve their stability. However, it is still an open question what is required to best perform such an attachment and the role of the support. In this work, six different AMPs were covalently attached to a long-ranged ordered amphiphilic hydrogel, with their antibacterial efficacy evaluated and compared to their performance when free in solution. Among the tested AMPs were four different versions of synthetic end-tagged AMPs where the sequence was altered to change the cationic residue as well as to vary the degree of hydrophobicity. Two previously well-studied AMPs, Piscidin 1 and Omiganan, were also included as comparisons. The antibacterial efficacy against Staphylococcus aureus remained largely consistent between free AMPs and those attached to surfaces. However, the activity pattern against Pseudomonas aeruginosa on hydrogel surfaces displayed a marked contrast to that observed in the solution. Additionally, all the AMPs showed varying degrees of hemolytic activity when in solution. This activity was entirely diminished, and all the AMPs were non-hemolytic when attached to the hydrogels.

Antimicrobial resistance of Pseudomonas aeruginosa: navigating clinical impacts, current resistance trends, and innovations in breaking therapies

Pseudomonas aeruginosa, a Gram-negative bacterium, is recognized for its adaptability and opportunistic nature. It poses a substantial challenge in clinical settings due to its complicated antibiotic resistance mechanisms, biofilm formation, and capacity for persistent infections in both animal and human hosts. Recent studies revealed a potential zoonotic transmission of P. aeruginosa between animals, the environment, and human populations which highlights awareness of this microbe. Implementation of the One Health approach, which underscores the connection between human, animal, and environmental health, we aim to offer a comprehensive perspective on the current landscape of P. aeruginosa management. This review presents innovative strategies designed to counteract P. aeruginosa infections. Traditional antibiotics, while effective in many cases, are increasingly compromised by the development of multidrug-resistant strains. Non-antibiotic avenues, such as quorum sensing inhibition, phage therapy, and nanoparticle-based treatments, are emerging as promising alternatives. However, their clinical application encounters obstacles like cost, side effects, and safety concerns. Effectively addressing P. aeruginosa infections necessitates persistent research efforts, advancements in clinical development, and a comprehension of host-pathogen interactions to deal with this resilient pathogen.

Synergistic bactericidal effects of phage-enhanced antibiotic therapy against MRSA biofilms

Methicillin-resistant Staphylococcus aureus (MRSA) causes biofilm-related medical device infections. Phage-antibiotic combinations offer potential therapy due to proven in vitro antibiofilm efficacy. We evaluated phage-antibiotic synergy against biofilms using modified checkerboard and 24-h time-kill assays. Humanized-simulated daptomycin (DAP) (10, 8, and 6 mg/kg q24h) and ceftaroline (CPT) (600 mg q12h) were combined with Intesti13, Sb-1, and Romulus phages (tMOI 1, q12h). Assays were conducted in 168-h biofilm reactor models against DAP non-susceptible (DNS) vancomycin intermediate S. aureus (VISA) MRSA D712 and DAP-susceptible MRSA 8014. Synergistic activity and bactericidal activity were defined as ≥2log10 CFU/mL reduction from antibiotic-only regimens and ≥3log10 CFU/mL decrease from baseline at 24 h. Differences were analyzed by one-way analysis of variance with Tukey's post hoc test (P ≤ 0.05 is considered significant). Surviving bacteria were examined for antibiotic minimum biofilm inhibitory concentration (MBIC) changes and phage susceptibility. In 168-h biofilm models, humanized DAP 10 mg/kg + CPT, combined with a 2-phage cocktail (Intesti13 + Sb-1) against D712, and a 3-phage cocktail (Intesti13 + Sb-1 + Romulus) against 8014, demonstrated synergistic bactericidal activity. At 168 h, bacteria were minimally detectable [2log10 CFU/cm2 (-Δ4.23 and -Δ4.42 log10 CFU/cm2; both P < 0.001)]. Antibiotic MBIC remained unchanged compared to baseline across various time points. None of the tested bacteria at 168 h exhibited complete phage resistance. This study reveals bactericidal efficacy of DAP + CPT with 2-phage and 3-phage cocktails against DNS VISA and MRSA isolates (D712 and 8014) in biofilm models, maintaining susceptibility. Further research is needed for diverse strains and durations, aligning with infection care.

IMPORTANCE

The prevalence of biofilm-associated medical device infections caused by methicillin-resistant Staphylococcus aureus (MRSA) presents a pressing medical challenge. The latest research demonstrates the potential of phage-antibiotic combinations (PACs) as a promising solution, notably in vitro antibiofilm efficacy. By adopting modified checkerboard and 24-h time-kill assays, the study investigated the synergistic action of phages combined with humanized-simulated doses of daptomycin (DAP) and ceftaroline (CPT). The results were promising: a combination of DAP, CPT, and either a 2-phage or 3-phage cocktail effectively exhibited bactericidal activity against both DAP non-susceptible vancomycin intermediate S. aureus MRSA and DAP-susceptible MRSA strains within 168-h biofilm models. Moreover, post-treatment evaluations revealed no discernible rise in antibiotic resistance or complete phage resistance. This pioneering work suggests the potential of PACs in addressing MRSA biofilm infections, setting the stage for further expansive research tailored to diverse bacterial strains and treatment durations.

Biosynthesized silver nanoparticles prevent bacterial infection in chicken egg model and mitigate biofilm formation on medical catheters

Investigating the application of innovative antimicrobial surface coatings on medical devices is an important field of research. Many of these coatings have significant drawbacks, including biocompatibility, coating stability and the inability to effectively combat multiple drug-resistant bacteria. In this research, we developed an antibiofilm surface coating for medical catheters using biosynthesized silver nanoparticles (b-Cs-AgNPs) developed using leaves extract of Calliandra surinamensis. Various characterization techniques were employed to thoroughly characterize the synthesized b-Cs-AgNPs and c-AgNPs. b-Cs-AgNPs were compatible with human normal kidney cells and chicken embryos. It did not trigger any skin inflammatory response in in vivo rat model. b-Cs-AgNPs demonstrated potent zone of inhibition of 19.09 mm when subjected to the disc diffusion method in E. coli confirming strong antibacterial property. Different anti-bacterial assays including liquid growth curve, colony counting assay, biofilm formation assay supported the potent antimicrobial efficacy of b-Cs-AgNPs alone and when coated to medical grade catheters. Mechanistic studies reveal the presence of ferulic acid, that was important for the synthesis of b-AgNPs along with enhanced antibacterial effects of b-Cs-AgNPs compared to c-AgNPs, supported by molecular docking analysis. These results together demonstrated the effective role b-Cs-AgNPs in combating infections and mitigating biofilm formations, highlighting their need for further study in the field of biomedical applications.

Biofilm-producing and carbapenems-resistant Escherichia coli nosocomial uropathogens: a cross-sectional study

OBJECTIVES

This cross-sectional study aims to determine the incidence and potential risk factors associated with biofilm-producing uropathogenic Escherichia coli (UPEC) nosocomial strains from a tertiary care hospital and to examine the prospective correlation between biofilm generation and antibiotic resistance phenotypes and genotypes.

METHODS

A total of 130 UPEC nosocomial isolates were identified, their biofilm formation was quantified using a modified microtiter plate assay, and their antibiotic susceptibilities were assessed utilizing the disc diffusion method. Isolates were then subjected to PCR assays targeting blaKPC, blaVIM, blaIMP, and blaOXA48 genes.

RESULTS

Over half of the isolates (n = 76, 58.5%) were biofilm producers. Among 17 carbapenem-resistant isolates, 6 (42.9%) isolates harbored the blaOXA48 gene, and only 1 (9.1%) isolate was positive for the blaVIM gene. Prior antibiotic therapy (aOR 15.782, p 0.000) and diabetes mellitus DM (aOR 11.222, p 0.016) were the significant risk factors associated with biofilm production, as determined by logistic regression analysis of the data. In addition, gentamicin resistance was the only statistically significant antibiotic resistance pattern associated with biofilm production (aOR 9.113, p 0.02).

CONCLUSIONS

The findings of this study emphasize the significance of implementing proper infection control measures to avoid the horizontal spread of biofilm formation and associated antimicrobial resistance patterns among UPEC nosocomial strains.

Genomic insights into virulence, antimicrobial resistance, and adaptation acumen of Escherichia coli isolated from an urban environment

Populations of common commensal bacteria such as Escherichia coli undergo genetic changes by the acquisition of certain virulence and antimicrobial resistance (AMR) encoding genetic elements leading to the emergence of pathogenic strains capable of surviving in the previously uninhabited or protected niches. These bacteria are also reported to be prevalent in the environment where they survive by adopting various recombination strategies to counter microflora of the soil and water, under constant selection pressure(s). In this study, we performed molecular characterization, phenotypic AMR analysis, and whole genome sequencing (WGS) of E. coli (n = 37) isolated from soil and surface water representing the urban and peri-urban areas. The primary aim of this study was to understand the genetic architecture and pathogenic acumen exhibited by environmental E. coli. WGS-based analysis entailing resistome and virulome profiling indicated the presence of various virulence (adherence, iron uptake, and toxins) and AMR encoding genes, including blaNDM-5 in the environmental isolates. A majority of our isolates belonged to phylogroup B1 (73%). A few isolates in our collection were of sequence type(s) (ST) 58 and 224 that could have emerged recently as clonal lineages and might pose risk of infection/transmission. Mobile genetic elements (MGEs) such as plasmids (predominantly) of the IncF family, prophages, pipolins, and insertion elements such as IS1 and IS5 were also observed to exist, which may presumably aid in the propagation of genes encoding resistance against antimicrobial drugs. The observed high prevalence of MGEs associated with multidrug resistance in pathogenic E. coli isolates belonging to the phylogroup B1 underscores the need for extended surveillance to keep track of and prevent the transmission of the bacterium to certain vulnerable human and animal populations.

IMPORTANCE

Evolutionary patterns of E. coli bacteria convey that they evolve into highly pathogenic forms by acquiring fitness advantages, such as AMR, and various virulence factors through the horizontal gene transfer (HGT)-mediated acquisition of MGEs. However, limited research on the genetic profiles of environmental E. coli, particularly from India, hinders our understanding of their transition to pathogenic forms and impedes the adoption of a comprehensive approach to address the connection between environmentally dwelling E. coli populations and human and veterinary public health. This study focuses on high-resolution genomic analysis of the environmental E. coli isolates aiming to understand the genetic similarities and differences among isolates from different environmental niches and uncover the survival strategies employed by these bacteria to thrive in their surroundings. Our approach involved molecular characterization of environmental samples using PCR-based DNA fingerprinting and subsequent WGS analysis. This multidisciplinary approach is likely to provide valuable insights into the understanding of any potential spill-over to human and animal populations and locales. Investigating these environmental isolates has significant potential for developing epidemiological strategies against transmission and understanding niche-specific evolutionary patterns.

Antibacterial and antibiofilm effects of Camellia oleifera seed dreg extract and its application in cosmetics

BACKGROUND

Cosmetic care products contain a high proportion of water and nutrients. Therefore, preventing bacterial growth is an important issue to ensure product quality and safety. The application of antibacterial natural ingredients derived from plants is considered to have the potential to maintain product quality and reduce the use of chemicals in formulations. Additionally, chemically synthesized antiseptic and antibacterial agents are widely used in the industry at present. However, some preservative ingredients have been reported that may cause skin irritation, redness, allergies, and even dermatitis.

AIMS

This study aimed to prepare extract from Camellia oleifera tea seed dregs (CTSD), investigate the antibacterial effects on two pathogenic bacteria and evaluate the product preservative ability.

METHODS

Ethanol extraction was prepared and subjected to characterize their triterpenoid contents. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) were determined for Pseudomonas aeruginosa and Staphylococcus aureus. The product's stability and preservative qualities, along with its ability to scavenge free radicals through antioxidant activity, were also assessed.

RESULTS

The gram-positive S. aureus showed greater susceptibility to the treatment. In additional, CTSD possessed significant free radical scavenging activity in vitro and cultured normal human skin fibroblast CCD-966SK cells under nontoxic concentration. The challenge test and accelerated storage test confirmed the CTSD containing formulated emulsion is eligible for commercialization.

CONCLUSIONS

CTSD has the potential to be developed as an alternative agent to control microbial biofilm formation, or can be used as an adjuvant compound for infectious disease control.

Synergistic effects of COVID-19 and Pseudomonas aeruginosa in chronic obstructive pulmonary disease: a polymicrobial perspective

This article discusses the connection between the novel coronavirus disease 2019 (COVID-19) caused by the coronavirus-2 (SARS-CoV-2) and chronic obstructive pulmonary disease (COPD). COPD is a multifaceted respiratory illness that is typically observed in individuals with chronic exposure to chemical irritants or severe lung damage caused by various pathogens, including SARS-CoV-2 and Pseudomonas aeruginosa. The pathogenesis of COPD is complex, involving a variety of genotypes and phenotypic characteristics that result in severe co-infections and a poor prognosis if not properly managed. We focus on the role of SARS-CoV-2 infection in severe COPD exacerbations in connection to P.  aeruginosa infection, covering pathogenesis, diagnosis, and therapy. This review also includes a thorough structural overview of COPD and recent developments in understanding its complicated and chronic nature. While COVID-19 is clearly linked to emphysema and chronic bronchitis at different stages of the disease, our understanding of the precise interaction between microbial infections during COPD, particularly with SARS-CoV-2 in the lungs, remains inadequate. Therefore, it is crucial to understand the host-pathogen relationship from the clinician's perspective in order to effectively manage COPD. This article aims to provide a comprehensive overview of the subject matter to assist clinicians in their efforts to improve the treatment and management of COPD, especially in light of the COVID-19 pandemic.

Improving Biocompatibility of Polyurethanes Apply in Medicine Using Oxygen Plasma and Its Negative Effect on Increased Bacterial Adhesion

Polyurethanes (PUs) are versatile polymers used in medical applications due to their high flexibility and fatigue resistance. PUs are widely used for synthetic blood vessels, wound dressings, cannulas, and urinary and cardiovascular catheters. Many scientific reports indicate that surface wettability is crucial for biocompatibility and bacterial adhesion. The use of oxygen plasma to modify PUs is advantageous because of its effectiveness in introducing oxygen-containing functional groups, thereby altering surface wettability. The purpose of this study was to investigate the effect of the modification of the oxygen plasma of polyurethane on its biocompatibility with lung tissue (A549 cell line) and the adhesion of Gram-positive bacteria (S. aureus and S. epidermidis). The results showed that the modification of polyurethane by oxygen plasma allowed the introduction of functional groups containing oxygen (-OH and -COOH), which significantly increased its hydrophilicity (change from 105° ± 2° to 9° ± 2°) of PUs. Surface analysis by atomic force microscopy (AFM) showed changes in PU topography (change in maximum height from ∼110.3 nm to ∼32.1 nm). Moreover, biocompatibility studies on A549 cells showed that on the PU-modified surface, the cells exhibited altered morphology (increases in cell surface area and length, and thus reduced circularity) without concomitant effects on cell viability. However, serial dilution and plate count and microscopic methods confirmed that plasma modification significantly increased the adhesion of S. aureus and S. epidermidis bacteria. This study indicate the important role of surface hydrophilicity in biocompatibility and bacterial adhesion, which is important in the design of new medical biomaterials.

Cell-free supernatants of probiotic consortia impede hyphal formation and disperse biofilms of vulvovaginal candidiasis causing Candida in an ex-vivo model

Vulvovaginal candidiasis is the second most common vaginal infection caused by drug-resistant Candida species that affects about 70-75% of reproductive age group women across the globe. As current-day antifungal drugs are ineffective against the biofilms formed by the drug-resistant Candida strains, several natural compounds and antagonistic microbes are being explored as alternative antifungal agents. In the present study, we investigated the anti-biofilm activity of Cell-Free Supernatant (CFS) extracted from the commercially available probiotics VSL-3 against the biofilms of Candida species and also evaluated their efficacy in curbing the yeast-to-hyphal transition. Various methodologies like crystal violet staining and scanning electron microscopy were used to study the effect of CFS against the biofilms formed by the species. The ability of CFS to interfere with yeast to hyphal transition in Candida was studied by colony morphology assay and visually confirmed with phase contrast microscopy. The potential of the CFS of the probiotics was also evaluated using goat buccal tissue, a novel ex-vivo model that mimics the vaginal environment. Moreover, the supernatant extracted from VSL-3 had the ability to down-regulate the expression of virulence genes of Candida from the biofilm formed over the ex-vivo model. These results emphasize the anti-fungal and anti-infective properties of the CFS of VSL-3 against drug-resistant Candida strains causing vulvovaginal candidiasis.

Anti-biofilm, drug delivery and cytotoxicity properties of dendrimers

Background and purpose

Treatments using antimicrobial agents have faced many difficulties as a result of biofilm formation by pathogenic microorganisms. The biofilm matrix formed by these microorganisms prevents antimicrobial agents from penetrating the interior where they can exact their activity effectively. Additionally, extracellular polymeric molecules associated with biofilm surfaces can absorb antimicrobial compounds, lowering their bioavailability. This problem has resulted in the quest for alternative treatment protocols, and the development of nanomaterials and devices through nanotechnology has recently been on the rise.

Research approach

The literature on dendrimers was searched for in databases such as Google Scholar, PubMed, and ScienceDirect.

Key results

As a nanomaterial, dendrimers have found useful applications as a drug delivery vehicle for antimicrobial agents against biofilm-mediated infections to circumvent these defense mechanisms. The distinctive properties of dendrimers, such as multi-valency, biocompatibility, high water solubility, non-immunogenicity, and biofilm matrix-/cell membrane fusogenicity (ability to merge with intracellular membrane or other proteins), significantly increase the efficacy of antimicrobial agents and reduce the likelihood of recurring infections.

Conclusion

This review outlines the current state of dendrimer carriers for biofilm treatments, provides examples of their real-world uses, and examines potential drawbacks.

Synthesis and in vitro evaluation of antibacterial and antibiofilm activities of novel triphenylphosphonium-functionalized substituted pyrimidines

The increase in the prevalence of antibiotic-resistant pathogens leads to a decrease in the number of antimicrobial agents for the treatment of infections and prompts researchers to search for new effective antimicrobial drugs. This study reports the synthesis of novel triphenylphosphonium-functionalized substituted pyrimidines and in vitro evaluation of their antibacterial and antibiofilm activity. Most of the synthesized derivatives showed high antibacterial activity (MIC = 0.39-1.56 μg/mL) against the methicillin-resistant strain of S. aureus 222. Compounds 2a and 11 exhibited a high level of antibiofilm activity against S. aureus 222 and E. coli 311. The triphenylphosphonium-containing pyrimidines 11 and 2a reduced S. aureus 222 biofilm formation by 99.1% and 95.8%, respectively. In addition, compound 2a was the most active against E. coli 311 biofilm formation (the biomass decreased by 98.4%).

Antibiotic Resistance of Helicobacter pylori: Mechanisms and Clinical Implications

Helicobacter pylori is a pathogenic bacterium associated with various gastrointestinal diseases, including chronic gastritis, peptic ulcers, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. The increasing rates of H. pylori antibiotic resistance and the emergence of multidrug-resistant strains pose significant challenges to its treatment. This comprehensive review explores the mechanisms underlying the resistance of H. pylori to commonly used antibiotics and the clinical implications of antibiotic resistance. Additionally, potential strategies for overcoming antibiotic resistance are discussed. These approaches aim to improve the treatment outcomes of H. pylori infections while minimizing the development of antibiotic resistance. The continuous evolution of treatment perspectives and ongoing research in this field are crucial for effectively combating this challenging infection.

Nanotechnology in the Diagnosis and Treatment of Antibiotic-Resistant Infections

The development of antimicrobial resistance (AMR), along with the relative reduction in the production of new antimicrobials, significantly limits the therapeutic options in infectious diseases. Thus, novel treatments, especially in the current era, where AMR is increasing, are urgently needed. There are several ongoing studies on non-classical therapies for infectious diseases, such as bacteriophages, antimicrobial peptides, and nanotechnology, among others. Nanomaterials involve materials on the nanoscale that could be used in the diagnosis, treatment, and prevention of infectious diseases. This review provides an overview of the applications of nanotechnology in the diagnosis and treatment of infectious diseases from a clinician's perspective, with a focus on pathogens with AMR. Applications of nanomaterials in diagnosis, by taking advantage of their electrochemical, optic, magnetic, and fluorescent properties, are described. Moreover, the potential of metallic or organic nanoparticles (NPs) in the treatment of infections is also addressed. Finally, the potential use of NPs in the development of safe and efficient vaccines is also reviewed. Further studies are needed to prove the safety and efficacy of NPs that would facilitate their approval by regulatory authorities for clinical use.

From Stress Tolerance to Virulence: Recognizing the Roles of Csps in Pathogenicity and Food Contamination

Be it for lab studies or real-life situations, bacteria are constantly exposed to a myriad of physical or chemical stresses that selectively allow the tolerant to survive and thrive. In response to environmental fluctuations, the expression of cold shock domain family proteins (Csps) significantly increases to counteract and help cells deal with the harmful effects of stresses. Csps are, therefore, considered stress adaptation proteins. The primary functions of Csps include chaperoning nucleic acids and regulating global gene expression. In this review, we focus on the phenotypic effects of Csps in pathogenic bacteria and explore their involvement in bacterial pathogenesis. Current studies of csp deletions among pathogenic strains indicate their involvement in motility, host invasion and stress tolerance, proliferation, cell adhesion, and biofilm formation. Through their RNA chaperone activity, Csps regulate virulence-associated genes and thereby contribute to bacterial pathogenicity. Additionally, we outline their involvement in food contamination and discuss how foodborne pathogens utilize the stress tolerance roles of Csps against preservation and sanitation strategies. Furthermore, we highlight how Csps positively and negatively impact pathogens and the host. Overall, Csps are involved in regulatory networks that influence the expression of genes central to stress tolerance and virulence.

Antibiofilm activity of marine microbial natural products: potential peptide- and polyketide-derived molecules from marine microbes toward targeting biofilm-forming pathogens

Controlling and treating biofilm-related infections is challenging because of the widespread presence of multidrug-resistant microbes. Biofilm, a naturally occurring matrix of microbial aggregates, has developed intricate and diverse resistance mechanisms against many currently used antibiotics. This poses a significant problem, especially for human health, including clinically chronic infectious diseases. Thus, there is an urgent need to search for and develop new and more effective antibiotics. As the marine environment is recognized as a promising reservoir of new biologically active molecules with potential pharmacological properties, marine natural products, particularly those of microbial origin, have emerged as a promising source of antibiofilm agents. Marine microbes represent an untapped source of secondary metabolites with antimicrobial activity. Furthermore, marine natural products, owing to their self-defense mechanisms and adaptation to harsh conditions, encompass a wide range of chemical compounds, including peptides and polyketides, which are primarily found in microbes. These molecules can be exploited to provide novel and unique structures for developing alternative antibiotics as effective antibiofilm agents. This review focuses on the possible antibiofilm mechanism of these marine microbial molecules against biofilm-forming pathogens. It provides an overview of biofilm development, its recalcitrant mode of action, strategies for the development of antibiofilm agents, and their assessments. The review also revisits some selected peptides and polyketides from marine microbes reported between 2016 and 2023, highlighting their moderate and considerable antibiofilm activities. Moreover, their antibiofilm mechanisms, such as adhesion modulation/inhibition targeting biofilm-forming pathogens, quorum sensing intervention and inhibition, and extracellular polymeric substance disruption, are highlighted herein.

Nitrogen and phosphorus eutrophication enhance biofilm-related drug resistance in Enterococcus faecalis isolated from Water Sources

Antibiotic resistance is a critical topic worldwide with important consequences for public health. So considering the rising issue of antibiotic-resistance in bacteria, we explored the impact of nitrogen and phosphorus eutrophication on drug resistance mechanisms in Enterococcus faecalis, especially ciprofloxacin, oxytetracycline, and ampicillin. For this purpose we examined the antibiotic-resistance genes and biofilm formation of Enterococcus faecalis under different concentration of nitrogen and phosphorus along with mentioned antibiotics. Mesocosms were designed to evaluate the impact of influence of eutrophication on the underlying mechanism of drugn resistence in Enterococcus faecalis. For this purpose, we explored the potential relation to biofilm formation, adhesion ability, and the expression levels of the regulatory gene fsrA and the downstream gene gelEI. Our results demonstrated that the isolates of all treatments displayed high biofilm forming potential, and fsrA and gelE genes expression. Additionally, the experimental group demonstrated substantially elevated Enterococcus faecalis gelE expression. Crystal violet staining was applied to observe biofilm formation during bacterial development phase and found higher biofilm formation. In conclusion, our data suggest that E. faecalis resistance to ciprofloxacin, oxytetracycline, and ampicillin is related to biofilm development. Also, the high level of resistance in Enterococcus faecalis is linked to the expression of the fsrA and gelE genes. Understanding these pathways is vital in tackling the rising problem of bacterial resistance and its potential effect on human health.

Quorum Sensing in Gram-Negative Bacteria: Strategies to Overcome Antibiotic Resistance in Ocular Infections

Truly miraculous medications and antibiotics have helped save untold millions of lives. Antibiotic resistance, however, is a significant issue related to health that jeopardizes the effectiveness of antibiotics and could harm everyone's health. Bacteria, not humans or animals, become antibiotic-resistant. Bacteria use quorum-sensing communication routes to manage an assortment of physiological exercises. Quorum sensing is significant for appropriate biofilm development. Antibiotic resistance occurs when bacteria establish a biofilm on a surface, shielding them from the effects of infection-fighting drugs. Acylated homoserine lactones are used as autoinducers by gram-negative microscopic organisms to impart. However, antibiotic resistance among ocular pathogens is increasing worldwide. Bacteria are a significant contributor to ocular infections around the world. Gram-negative microscopic organisms are dangerous to ophthalmic tissues. This review highlights the use of elective drug targets and treatments, for example, combinational treatment, to vanquish antibiotic-resistant bacteria. Also, it briefly portrays anti-biotic resistance brought about by gram-negative bacteria and approaches to overcome resistance with the help of quorum sensing inhibitors and nanotechnology as a promising medication conveyance approach to give insurance of anti-microbials and improve pathways for the administration of inhibitors of quorum sensing with a blend of anti-microbials to explicit target destinations and penetration through biofilms for treatment of ocular infections. It centres on the methodologies to sidestep the confinements of ocular anti-biotic delivery with new visual innovation.

How Do Phages Disrupt the Structure of Enterococcus faecalis Biofilm?

Biofilms are composed of multicellular communities of microbial cells and their self-secreted extracellular polymeric substances (EPS). The viruses named bacteriophages can infect and lyze bacterial cells, leading to efficient biofilm eradication. The aim of this study was to analyze how bacteriophages disrupt the biofilm structure by killing bacterial cells and/or by damaging extracellular polysaccharides, proteins, and DNA. The use of colorimetric and spectrofluorimetric methods and confocal laser scanning microscopy (CLSM) enabled a comprehensive assessment of phage activity against E. faecalis biofilms. The impact of the phages vB_Efa29212_2e and vB_Efa29212_3e was investigated. They were applied separately or in combination on 1-day and 7-day-old biofilms. Phages 2e effectively inhibited the growth of planktonic cells with a limited effect on the biofilm. They did not notably affect extracellular polysaccharides and proteins; however, they increased DNA levels. Phages 3e demonstrated a potent and dispersing impact on E. faecalis biofilms, despite being slightly less effective than bacteriophages 2e against planktonic cells. Phages 3e reduced the amount of extracellular polysaccharides and increased eDNA levels in both 1-day-old and 7-day-old biofilm cultures. Phage cocktails had a strong antimicrobial effect on both planktonic and biofilm-associated bacteria. A significant reduction in the levels of polysaccharides, proteins, and eDNA in 1-day-old biofilm samples was noted, which confirms that phages interfere with the structure of E. faecalis biofilm by killing bacterial cells and affecting extracellular polymer levels.

Orthopaedic Wire Debridement: A Novel Surgical Technique for Hypergranulated Burn Wounds

The burn wound healing process can be protracted due to various factors, including burn depth, infection and hypergranulation. Hypergranulation impedes epithelialisation macroscopically by preventing cellular migration across the wound bed and microscopically through cell-to-cell signal interferences. Debridement, which is the act of removing necrotic tissue, hypergranulation, slough and foreign debris from the wound in order to expose the underlying viable bed, can be achieved using various techniques. This aids with wound bed preparation to facilitate and expedite healing. In this article, we present a novel surgical debridement technique using a malleable orthopaedic cerclage wire for the management of a hypergranulated burn wound.