Antibiofilm Effect of Biogenic Silver Nanoparticles Combined with Oregano Derivatives against Carbapenem-Resistant Klebsiella pneumoniae

Abstract

Resistant bacteria may kill more people than COVID-19, so the development of new antibacterials is essential, especially against microbial biofilms that are reservoirs of resistant cells. Silver nanoparticles (bioAgNP), biogenically synthesized using Fusarium oxysporum, combined with oregano derivatives, present a strategic antibacterial mechanism and prevent the emergence of resistance against planktonic microorganisms. Antibiofilm activity of four binary combinations was tested against enteroaggregative Escherichia coli (EAEC) and Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC): oregano essential oil (OEO) plus bioAgNP, carvacrol (Car) plus bioAgNP, thymol (Thy) plus bioAgNP, and Car plus Thy. The antibiofilm effect was accessed using crystal violet, MTT, scanning electron microscopy, and Chromobacterium violaceum anti-quorum-sensing assays. All binary combinations acted against preformed biofilm and prevented its formation; they showed improved antibiofilm activity compared to antimicrobials individually by reducing sessile minimal inhibitory concentration up to 87.5% or further decreasing biofilm metabolic activity and total biomass. Thy plus bioAgNP extensively inhibited the growth of biofilm in polystyrene and glass surfaces, disrupted three-dimensional biofilm structure, and quorum-sensing inhibition may be involved in its antibiofilm activity. For the first time, it is shown that bioAgNP combined with oregano has antibiofilm effect against bacteria for which antimicrobials are urgently needed, such as KPC.

Antimicrobial Activity of Bovine Bone Scaffolds Impregnated with Silver Nanoparticles on New Delhi Metallo-β-Lactamase-Producing Gram-Negative Bacilli Biofilms

“…Electrostatic interactions between negatively charged groups in the biofilm and the charged wire may also be expected to cause biofilm expansion when the wire is cathodic and contraction when the wire is anodic. A study that evaluated AgNPs with plant extracts demonstrated, in the evaluation of an isolated group of AgNPs, no change in the production of biofilms in KPC-producing K. pneumoniae, the same result as that found in our study [38].…”

Inhibitory effect of natural compounds on quorum sensing system in Pseudomonas aeruginosa: a helpful promise for managing biofilm community

“…Additionally, thymol showed inhibitory effects against the QS system in other microorganisms; however, data about the interactions of this compound with the P. aeruginosa QS system is limited. Thus, the inhibitory effect of thymol on the QS system of P. aeruginosa is one possible antibiofilm effect of this natural compound; however, more confirmatory studies are required on this issue ( Cáceres et al, 2020 ; Scandorieiro et al, 2023 ).…”

Relationship between biofilm formation and antibiotic resistance of Klebsiella pneumoniae and updates on antibiofilm therapeutic strategies

“…Siddique et al reported the efficacy of silver nanoparticle AgNP in inhibiting biofilm formation by reducing the production of extracellular polymeric substances, and AgNPs (100 mg/ ml) exhibited a percentage inhibition of 64% for K. pneumoniae strain MF953600 and 86% for MF953599 (Siddique et al, 2020). In another study, Scandorieiro et al demonstrated that the combination of oregano essential oil (OEO) and their bioactive components with biogenic silver nanoparticles (bioAgNP) enhanced bacteriolytic activity (Scandorieiro et al, 2023). Oregano essential oil (OEO), carvacrol (Car) and thymol (Thy) alone have been shown to prevent biofilm formation and decrease metabolic activity of preformed biofilm in KPC-producing K. pneumoniae.…”