Aug 2026· International Microbiology· 0 citations· 44 references
Medicine
TL;DR
It is suggested that biogenically synthesized MgO NPs hold considerable promise as antibacterial and antibiofilm agents against MDR Gram-negative pathogens.
Abstract
Antibiotic resistance among Gram-negative bacteria, particularly those capable of forming biofilms, has become a serious clinical challenge with limited treatment options. In this study, magnesium oxide nanoparticles (MgO NPs) were synthesized using a green, cost-effective approach based on aqueous leaf extract of Cymbopogon citratus (lemongrass) and evaluated for their antibacterial and antibiofilm potential against multidrug resistant (MDR) clinical isolates of Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli. Minimum inhibitory concentration (MIC) values determined by broth microdilution ranged from 250 to 500 µg/ml, and minimum bactericidal concentration (MBC) values ranged from 1000 to 2000 µg/ml. Antibacterial activity assessed by the well diffusion method was dose-dependent, with inhibition zones ranging from 18 to 28 mm. The effect of MgO NPs on biofilm formation and eradication of pre-formed biofilms was evaluated using microtiter plate assay with crystal violet staining. Percentage inhibition of biofilm formation ranged from 27 to 97.1%, while eradication of established biofilms ranged from 51.9 to 96.4%. Exposure to sub-inhibitory concentrations of MgO NPs led to a 2 to 3-fold increase in reactive oxygen species (ROS) production in treated cells compared to controls. MgO NPs also significantly reduced the protein, carbohydrate, and DNA content of the biofilm matrix. Swimming, swarming, and twitching motility were markedly reduced in treated isolates. Congo red agar assay confirmed that slime production was inhibited following NP treatment. These findings suggest that biogenically synthesized MgO NPs hold considerable promise as antibacterial and antibiofilm agents against MDR Gram-negative pathogens.
A major obstacle to successful antimicrobial therapy is the rising incidence of multidrug-resistant (MDR) bacterial infections, especially those brought on by ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.). The development of biofilms increases bacterial resistance to antibiotics and fuels chronic infections. Green-synthesised zinc oxide nanoparticles (ZnO NPs), made from the leaf extract of Bauhinia variegata, were tested for their antibacterial and antibiofilm properties against clinically isolated MDR ESKAPE pathogens both alone and in combination with specific antibiotics. Agar well diffusion, checkerboard synergy assays, broth microdilution, and microtiter plate biofilm inhibition techniques were used to measure the antimicrobial activity. With minimum inhibitory concentrations (MICs) ranging from 15.64 to 500 µg/mL, ZnO NPs demonstrated broad-spectrum antibacterial activity. Pseudomonas aeruginosa had the lowest MIC. ZnO NPs and imipenem were found to work synergistically against several isolates, and ZnO NPs and gentamicin were found to work synergistically against Enterococcus faecium and Enterobacter species. The range of biofilm inhibition was 26.3% to 80%, with Enterobacter spp. treated with ZnO NPs and gentamicin showing the largest decrease. These 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.
Jazab Naeem, Muhammad Mubeen Ahmad, Syed Kashif Raza et al.· Bulletin of University of Ag...· 0 citations
Background: Gram-negative bacteria resistant to multiple drugs are a major cause of illness and death worldwide. Their remarkable capacity to develop resistance to antibiotics makes them a serious concern in medical practice. Methods: A simple, green, novel method is used to synthesize ZnO nanoparticles (ZnO NPs) using ethanolic extracts of Diplazium esculentum via precipitation. Results: ZnO NPs exhibit a hexagonal structure with a particle size of ~30 nm and a band gap of 3.24 eV. The defect sites formed in ZnO NPs were estimated using prominent peaks in the photoluminescence spectra. ZnO NPs displayed a more than 4-log reduction in multi-drug-resistant E. coli and K. pneumoniae clinical isolates at a 500 μg/mL concentration. Moreover, ZnO NPs significantly reduced the biofilm bacterial cell viability of clinical isolates of Gram-negative bacteria. Complete eradication of biofilms was achieved for drug-resistant E. coli clinical isolates using a combination of sub-MIC of gentamicin and 500 μg/mL ZnO NPs. Green-synthesized ZnO NPs did not induce oxidative stress in mice, as indicated by unchanged GST, GSH, and thiol levels across all the tested organs. ZnO NPs showed both antibacterial and antibiofilm efficacy against drug-resistant strains of E. coli, K. pneumoniae, and S. aureus and completely eradicated E. coli biofilm in combination with gentamicin. Conclusions: Our study focuses on the sustainable synthesis of biocompatible ZnO NPs for the treatment of infections caused by pathogens belonging to the high-priority ESKAPE group.
Akshit Malhotra, Kwthar Debbarma, Sangita Jana et al.· Pharmaceutics· 0 citations
Abstract Multidrug-resistant (MDR) Pseudomonas aeruginosa infections are difficult to treat due to biofilm formation. This study evaluates the antimicrobial and antibiofilm efficacy of murepavadin (MUR), a novel peptidomimetic targeting the LptD protein, alone and combined with conventional antibiotics against clinical isolates. The minimum inhibitory concentrations (MICs) of 50 isolates against MUR and five antibiotics were determined. Synergy in planktonic cultures was assessed by checkerboard assays. For biofilm, the Bliss independence model was applied using MBIC (minimum biofilm inhibitory concentration) and the concentration yielding ≥90% biomass reduction, as measured by crystal violet (CV) staining. MUR showed potent activity against planktonic cells (MIC50/90: 0.25/0.5 mg l–1). Synergy tests revealed consistent MUR-colistin synergy across all strains, with notable interactions against carbapenemase-producers when combined with meropenem. In biofilms, MUR demonstrated significantly lower MBIC and lower concentrations required for ≥90% biomass reduction (CV staining). Bliss analysis confirmed strong synergistic biofilm inhibition in all combinations, most pronounced with tobramycin. MUR exhibits high efficacy against both planktonic and biofilm-forming MDR P. aeruginosa. Its synergy with colistin and tobramycin highlights its potential as a strategic combination partner.
Umut Yılmaz, Özlem Erkoç Güleryüz, Mehmet Ünlü et al.· Biofouling (Print)· 0 citations
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.
Biofilm associated infection is responsible for majority of chronic bacterial diseases. The conventional antimicrobial has not been able to cope with the increasing level of resistance. Nigella sativa L. (commonly called black cumin or black seed) has demonstrated diverse pharmacological properties, but standardized quantitative phenotypic assessment of its crude solvent extracts against Pseudomonas aeruginosa biofilms at subinhibitory concentrations remains limited. This study evaluated the in vitro antibacterial and antibiofilm effects of ethanolic and methanolic N. sativa seed extracts against P. aeruginosa ATCC 27853. Antibacterial activity was determined by agar well diffusion, yielding inhibition zones of 26.50 ± 0.87 mm (ethanolic) and 28.00 ± 1.15 mm (methanolic). Broth microdilution established identical MIC and MBC values of 250 μg/mL and 500 μg/mL, respectively, for both extracts. Biofilm inhibition was assessed by the tissue culture plate method with crystal violet staining at sub-MIC concentrations (125.00 to 7.81 μg/mL). The untreated control exhibited strong adherence. Following treatment, biofilm categories decreased to weak or moderate adherence. Percentage inhibition ranged from 68.34% to 89.45%, with the methanolic extract achieving 89.45% inhibition at 125.00 μg/mL. These findings indicate that N. sativa seed extracts possess antibiofilm potential against P. aeruginosa at subinhibitory concentrations. However, as this was a purely phenotypic study, the mechanisms underlying the observed inhibition remain speculative and require direct experimental investigation.
Kehinde Sowunmi, Micheal Omeyiza Ibrahim, O. Ogundele et al.· Nepal Journal of Biotechnolo...· 0 citations
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.
Juliane Zacour Marinho, Luiz Felipe Carreiro Machado, I. P. Ceravolo et al.· GAZI UNIVERSITY JOURNAL OF S...· 0 citations
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