Potentiating Gentamicin Efficacy Against Biofilms of Clinically Relevant Gram-Negative Bacteria Using Biosynthesized ZnO Nanoparticles

Antibiofilm potential of biogenic magnesium oxide nanoparticles against multidrug resistant gram-negative bacteria.

It is suggested that biogenically synthesized MgO NPs hold considerable promise as antibacterial and antibiofilm agents against MDR Gram-negative pathogens.

Green Synthesized Zinc Oxide Nanoparticles as Antibacterial and Antibiofilm Agents against Multidrug-Resistant ESKAPE Pathogens

Results show that green-synthesized ZnO nanoparticles have strong antibacterial and antibiofilm potential and can boost the effectiveness of traditional antibiotics, indicating their potential as supplemental agents in MDR bacterial infection management strategies.

Synthesis of zinc oxide nanoparticles and their effect on biofilm of methicillin-resistant Staphylococcus aureus isolates.

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) poses a growing threat in Iranian healthcare settings, and biofilm formation exacerbates treatment challenges. This study assessed the antibacterial and anti-biofilm potential of zinc oxide nanoparticles ZnONPs against 58 clinical MRSA isolates collected from hospitals in Iran. METHODS Isolates were identified via microbial and biochemical tests and confirmed by PCR targeting nuc (279 bp) and mecA (310 bp) genes. Antimicrobial susceptibility was evaluated using CLSI disk diffusion guidelines. The ZnONPs were synthesized by chemical precipitation. Minimum inhibitory concentrations (MICs) of ZnONPs were determined by broth microdilution, and biofilm formation/inhibition was quantified using crystal violet staining. RESULTS Of 131 S. aureus isolates, 58 (44.3%) were MRSA, exhibiting high resistance to Penicillin (100%), Erythromycin (91.4%), and Ciprofloxacin (74.1%), but full susceptibility to Trimethoprim-Sulfamethoxazole. ZnONPs displayed potent activity, with MICs ranging from 8 to 1024 µg/mL (MIC₅₀ = 64 µg/mL; MIC₉₀ = 512 µg/mL); 27.6% of isolates were inhibited at ≤ 16 µg/mL. Among MRSA, 15.5% were strong biofilm producers, and sub-MIC (½ MIC) concentrations of ZnONPs reduced biofilm by 82.3 ± 7.6% (P  < 0.001). Dynamic light scattering confirmed nanoparticle stability (size: 29.4 ± 4.2 nm; PDI: 0.19). CONCLUSIONS These findings highlight ZnONPs as a promising, low-cost alternative for managing MRSA infections, particularly in biofilm-associated cases, warranting further clinical exploration in resource-limited settings.

Green-synthesized ZnO nanoparticles from endophytic fungi inhibit virulence exoenzymes and biofilm formation in Staphylococcus aureus

The rapid emergence of multidrug-resistant Staphylococcus aureus (MRSA), specifically, methicillin-resistant strains, has become a global health concern. Biofilm-forming ability, enhanced virulence and resistance to multiple antibiotics have challenged treatment strategies. Therefore, immediate attention is necessary to design alternative therapeutic strategies including nanotechnology-based solutions, novel drug targets, and anti-virulence strategies, to combat this global public health threat. Findings of this study elucidates the binding interaction and inhibition potential of zinc oxide nanoparticles (ZnONPs) biosynthesized using an endophytic isolate obtained from Hibiscus rosa-sinensis and identified as Penicillium citrinum using morphology and ITS rRNA gene sequencing. The comprehensive characterization of biosynthesized ZnONPs was done using UV- visible spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential analysis. XRD and TEM analyses revealed the ZnONPs with spherical to elliptical shape with mean size of ~58 nm. The FTIR analysis confirmed the functional groups responsible for stabilizing and capping of ZnONPs. The biosynthesized ZnONPs displayed colloidal stability with a mean hydrodynamic diameter of 240.4 nm with a ζ-potential of −13 mV, as revealed in Dynamic light scattering (DLS) studies. The anti-staphylococcal studies of ZnONPs revealed an excellent antibacterial activity (22 ± 1.42) with a minimum inhibitory concentration (MIC) of 1000 µg/mL and demonstrated time-dependent bactericidal effects as revealed in time-kill assay. In addition, ZnONPs inhibited biofilm formation in a concentration-dependent manner, with highest reduction (68.7% ± 1.12%) in biofilm biomass, as revealed in a dye-based assay, accompanied by suppression of metabolic activity in biofilm-embedded cells. Importantly, ZnONPs displayed excellent inhibitory activities against the key virulence-associated exoenzymes, including lipase (IC₅₀ ≈ 380 ± 1.12) and hyaluronidase (IC₅₀ ≈ 330 ± 1.12 µg/mL). The cytotoxicity assessment using human red blood cells (hRBCs) revealed negligible haemolytic activity (< 2%) at biologically effective concentrations, confirming their safety and hemocompatibility. Considering the green synthesis, biocompatible nature and outstanding anti-staphylococcal potential, the endophyte derived ZnONPs showcases their potential as a sustainable nanotechnology-based alternative to conventional antimicrobial strategies against biofilm-associated infections of S. aureus.

Hydrothermal synthesis of silver vanadate nanoparticles, antimicrobial and anti-inflammatory potentials, cytotoxicity and interference on the activity of antimicrobial drugs

Bacterial resistance to antimicrobial drugs represents a critical threat to global health, compromising the efficacy of standard therapies. In this study, we evaluated the antimicrobial properties of silver vanadate microrods (SVMs) against clinical isolates of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. SVMs were active against all tested isolates, with MIC values of 128 µg/mL for S. aureus and 256 µg/mL for Gram-negative species. Notably, checkerboard assays revealed synergistic interactions with azithromycin, clindamycin, and sulfamethoxazole (FICi 0.093-0.125), indicating that SVM might potentiate the activity of antimicrobial drugs. The MBC/MIC ratio classified SVM as bactericidal against Gram-negative isolates and bacteriostatic against S. aureus. Scanning electron microscopy suggested a membrane disruption mechanism by a direct nanoparticle-bacteria interaction. SVM also exhibited anti-inflammatory activity comparable to tenoxicam in vitro. SVM presented cytotoxicity to BGM cells at 3.13 µg/mL (CC50). Our findings suggest that SVM is a promising candidate for combination therapy, warranting further investigation with surface-functionalized formulations to improve its selectivity.

Bioengineered ZnO/Activated Carbon Nanocomposites for Combating Multidrug-resistant Bacterial Strains