Green fabrication of anti-bacterial biofilm layer on endotracheal tubing using silver nanoparticles embedded in polyelectrolyte multilayered film

Antibacterial and antibiofilm efficacy of Solanum lasiocarpum root extract synthesized silver/silver chloride nanoparticles against Staphylococcus haemolyticus associated with bovine mastitis

Staphylococcus haemolyticus is a cause of bovine mastitis, leading to inflammation in the mammary gland. This bacterial infection adversely affects animal health, reducing milk quality and yield. Its emergence has been widely reported, representing a significant economic loss for dairy farms. Interestingly, S. haemolyticus exhibits higher levels of antimicrobial resistance than other coagulase-negative Staphylococci. In this study, we synthesized silver/silver chloride nanoparticles (Ag/AgCl-NPs) using Solanum lasiocarpum root extract and evaluated their antibacterial and antibiofilm activities against S. haemolyticus. The formation of the Ag/AgCl-NPs was confirmed using UV-visible spectroscopy, which revealed maximum absorption at 419 nm. X-ray diffraction (XRD) analysis demonstrated the crystalline nature of the Ag/AgCl-NPs, exhibiting a face-centered cubic lattice. Fourier transform infrared (FT-IR) spectroscopy elucidated the functional groups potentially involved in the Ag/AgCl-NPs synthesis. Transmission electron microscopy (TEM) analysis revealed that the average particle size of the Ag/AgCl-NPs was 10 nm. Antimicrobial activity results indicated that the minimum inhibitory concentration (MIC) and maximum bactericidal concentration (MBC) of the Ag/AgCl-NPs treatment were 7.82-15.63 μg/mL towards S. haemolyticus. Morphological changes in bacterial cells treated with the Ag/AgCl-NPs were observed under scanning electron microscopy (SEM). The Ag/AgCl-NPs reduced both the biomass of biofilm formation and preformed biofilm by approximately 20.24-94.66 % and 13.67-88.48 %. Bacterial viability within biofilm formation and preformed biofilm was reduced by approximately 21.56-77.54 % and 18.9-71.48 %, respectively. This study provides evidence of the potential of the synthesized Ag/AgCl-NPs as an antibacterial and antibiofilm agent against S. haemolyticus.

All-in-one properties of an anticancer-covered airway stent for the prevention of malignant central airway obstruction

Malignant central airway obstruction (MCAO) resulting from tumor metastasis and compression severely impairs respiration, posing life-threatening risks. To address this, we employed a synergistic modification strategy, combining cisplatin (CIS) and silver nanoparticles (AgNPs). Polycaprolactone (PCL) served as a drug carrier, enabling the preparation of a functional CIS@AgNPs@PCL fiber membrane-covered airway stent via electrospinning. This approach aimed to enhance the patency rate of MCAO. Characterization via ATR-FTIR, scanning electron microscope-energy-dispersive spectroscopy, and transmission electron microscope confirmed successful immobilization of CIS and AgNPs onto the stent surface. CIS@AgNPs@PCL substantially suppressed non-small cell lung cancer cells (A549), causing DNA damage, ultrastructural disruption, and over 50% apoptosis in 48 h. It also displayed potent antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans biofilms. A mouse subcutaneous tumor recurrence model assessed anti-cancer efficacy. CIS@AgNPs@PCL fiber-covered stents significantly inhibited lung cancer tissue and enhanced anti-cancer effects by up-regulating caspase-3 and Bax, while down-regulating Bcl-2. This study's functional airway stent provides a proof-of-concept for an integrated anti-cancer and antibacterial strategy. It promptly restores the lumen, inhibits biofilm formation, prevents tumor progression, and improves postoperative MCAO patency.

Antimicrobial Solutions for Endotracheal Tubes in Prevention of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia is one of the most frequently encountered hospital infections and is an essential issue in the healthcare field. It is usually linked to a high mortality rate and prolonged hospitalization time. There is a lack of treatment, so alternative solutions must be continuously sought. The endotracheal tube is an indwelling device that is a significant culprit for ventilator-associated pneumonia because its surface can be colonized by different types of pathogens, which generate a multispecies biofilm. In the paper, we discuss the definition of ventilator-associated pneumonia, the economic burdens, and its outcomes. Then, we present the latest technological solutions for endotracheal tube surfaces, such as active antimicrobial coatings, passive coatings, and combinatorial methods, with examples from the literature. We end our analysis by identifying the gaps existing in the present research and investigating future possibilities that can decrease ventilator-associated pneumonia cases and improve patient comfort during treatment.

Antimicrobial materials for endotracheal tubes: A review on the last two decades of technological progress

Ventilator-associated pneumonia (VAP) is an unresolved problem in nosocomial settings, remaining consistently associated with a lack of treatment, high mortality, and prolonged hospital stay. The endotracheal tube (ETT) is the major culprit for VAP development owing to its early surface microbial colonization and biofilm formation by multiple pathogens, both critical events for VAP pathogenesis and relapses. To combat this matter, gradual research on antimicrobial ETT surface coating/modification approaches has been made. This review provides an overview of the relevance and implications of the ETT bioburden for VAP pathogenesis and how technological research on antimicrobial materials for ETTs has evolved. Firstly, certain main VAP attributes (definition/categorization; outcomes; economic impact) were outlined, highlighting the issues in defining/diagnosing VAP that often difficult VAP early- and late-onset differentiation, and that generate misinterpretations in VAP surveillance and discrepant outcomes. The central role of the ETT microbial colonization and subsequent biofilm formation as fundamental contributors to VAP pathogenesis was then underscored, in parallel with the uncovering of the polymicrobial ecosystem of VAP-related infections. Secondly, the latest technological developments (reported since 2002) on materials able to endow the ETT surface with active antimicrobial and/or passive antifouling properties were annotated, being further subject to critical scrutiny concerning their potentialities and/or constraints in reducing ETT bioburden and the risk of VAP while retaining/improving the safety of use. Taking those gaps/challenges into consideration, we discussed potential avenues that may assist upcoming advances in the field to tackle VAP rampant rates and improve patient care. STATEMENT OF SIGNIFICANCE: The use of the endotracheal tube (ETT) in patients requiring mechanical ventilation is associated with the development of ventilator-associated pneumonia (VAP). Its rapid surface colonization and biofilm formation are critical events for VAP pathogenesis and relapses. This review provides a comprehensive overview on the relevance/implications of the ETT biofilm in VAP, and on how research on antimicrobial ETT surface coating/modification technology has evolved over the last two decades. Despite significant technological advances, the limited number of gathered reports (46), highlights difficulty in overcoming certain hurdles associated with VAP (e.g., persistent colonization/biofilm formation; mechanical ventilation duration; hospital length of stay; VAP occurrence), which makes this an evolving, complex, and challenging matter. Challenges and opportunities in the field are discussed.

Biogenic nanosilver-fabricated endotracheal tube to prevent microbial colonization in a veterinary hospital

COVID-19 patients have often required prolonged endotracheal intubation, increasing the risk of developing ventilator-associated pneumonia (VAP). A preventive strategy is proposed based on an endotracheal tube (ETT) modified by the in situ deposition of eucalyptus-mediated synthesized silver nanoparticles (AgNPs). The surfaces of the modified ETT were embedded with AgNPs of approximately 28 nm and presented a nanoscale roughness. Energy dispersive X-ray spectroscopy confirmed the presence of silver on and inside the coated ETT, which exhibited excellent antimicrobial activity against Gram-positive and Gram-negative bacteria, and fungi, including multidrug-resistant clinical isolates. Inhibition of planktonic growth and microbial adhesion ranged from 99 to 99.999% without cytotoxic effects on mammalian cells. Kinetic studies showed that microbial adhesion to the coated surface was inhibited within 2 h. Cell viability in biofilms supplemented with human tracheal mucus was reduced by up to 95%. In a porcine VAP model, the AgNPs-coated ETT prevented adhesion of Pseudomonas aeruginosa and completely inhibited bacterial invasion of lung tissue. The potential antimicrobial efficacy and safety of the coated ETT were established in a randomized control trial involving 47 veterinary patients. The microbial burden was significantly lower on the surface of the AgNPs-coated ETT than on the uncoated ETT (p < 0.05). KEY POINTS: • Endotracheal tube surfaces were modified by coating with green-synthesized AgNPs • P. aeruginosa burden of endotracheal tube and lung was reduced in a porcine model • Effective antimicrobial activity and safety was demonstrated in a clinical trial.

Antimicrobial Coating: Tracheal Tube Application

Ventilator-associated pneumonia (VAP) is a common and serious nosocomial infection in mechanically ventilated patients, increasing mortality, prolonging the patient length of stay, and increasing costs. In recent years, extensive studies on ventilator-associated pneumonia have shown that tracheal intubation plays an essential role in the pathogenesis of VAP, with the primary mechanism being the rapid colonization of the tracheal intubation surface by microbiota. Antibiotics do not combat microbial airway colonization, and antimicrobial coating materials offer new ideas to solve this problem. This paper reviews the current research progress on the role of endotracheal tube (ET) biofilms in the pathogenesis of VAP and antimicrobial coating materials.

Prevention of nosocomial transmission and biofilm formation on novel biocompatible antimicrobial gloves impregnated with biosynthesized silver nanoparticles synthesized using Eucalyptus citriodora leaf extract

Failure in the prevention of cross-transmission from contaminated gloves has been recognized as an important factor that contributes to the spread of several healthcare-associated infections. Ex situ coating process with silver nanoparticles (AgNPs) using Eucalyptus citriodora ethanolic leaf extract as reducing and capping agents to coat glove surfaces has been developed to prevent this mode of transmission. Elemental analysis of coated gloves showed 24.8 Wt% silver densely adhere on the surface. The coated gloves fully eradicated important hospital-acquired pathogens including Gram-positive bacteria, Gram-negative bacteria, and yeasts within 1 h. The coated gloves showed significant reduction, an average of five logs when tested against all standard strains and most clinical isolates (p < 0.01). Following prolonged exposure, the coating significantly reduced the numbers of most adhered pathogenic species, compared with uncoated gloves (p < 0.0001). AgNPs-coated gloves reduced microbial adhesion of mixed-species biofilms. A series of contamination and transmission assays demonstrated no transmission of viable organisms. Biocompatibility analysis confirmed high viability of HaCaT and L929 cells at all concentrations of AgNPs tested. The coated gloves were non-toxic with direct contact with L929 cells. The highly efficacious AgNPs-coated gloves potentially provide additional protection against transmission of healthcare-associated infections.

Facile deposition of biogenic silver nanoparticles on porous alumina discs, an efficient antimicrobial, antibiofilm, and antifouling strategy for functional contact surfaces

Surface modification is an emerging strategy for the design of contact materials. Fabricated alumina discs were functionalized by deposition of biogenic silver nanoparticles. The surfaces were characterized for physico-chemical, antibacterial and antibiofilm properties against microbial pathogens. The surface demonstrated improved hydrophobicity and a surface silver nanoparticle content of 6.4 w%. A reduction of more than 99.9% in CFU mL^-i was observed against the Gram-positive and Gram-negative bacteria tested, with >90% reduction of the fungal isolate. After 4 h, microbial adhesion was reduced by >99.9 and 90% for Escherichia coli and Staphylococcus aureus, respectively. Scanning electron micrographs further revealed a biofilm reduction. Cell viability tests indicated a bioincompatibility higher than 80% with Caco-2 and HaCaT cell lines after 48 h contact. The results suggest that deposition of biogenic silver nanoparticles on the surface of contact materials could be employed as a strategy to prevent biofilm formation.

Prolonged inhibitory effects against planktonic growth, adherence, and biofilm formation of pathogens causing ventilator-associated pneumonia using a novel polyamide/silver nanoparticle composite-coated endotracheal tube

Microbial cells can rapidly form biofilm on endotracheal tubes (ETT) causing ventilator-associated pneumonia, a serious complication in patients receiving mechanical ventilation. A novel polyamide with a good balance of hydrophilic/hydrophobic moieties was used for the embedment of green-reduction silver nanoparticles (AgNPs) for the composite-coated ETT. The films were conformal with a thickness of ∼ 17 ± 3 µm accommodating high loading of 60 ± 35 nm spherical-shaped AgNPs. The coated ETT resulted in a significant difference in reducing both planktonic growth and microbial adhesion of single and mixed-species cultures, compared with uncoated ETT (p < 0.05). A time-kill assay demonstrated rapid bactericidal effects of the coating on bacterial growth and cell adhesion to ETT surface. Biofilm formation by Pseudomonas aeruginosa and Staphylococcus aureus, commonly encountered pathogens, was inhibited by > 96% after incubation for 72 h. Polyamide/AgNP composite-coated ETT provided a broad-spectrum activity against both Gram-positive and Gram-negative bacteria as well as Candida albicans and prolonged antimicrobial activity.