Down-regulation of β-lactam antibiotics resistance and biofilm formation by Staphylococcus epidermidis is associated with isookanin

Abstract

IntroductionBiofilm formation is the major pathogenicity of Staphylococcus epidermidis (S. epidermidis), which enhances bacterial resistance to antibiotics. Isookanin has potential inhibitory activity on biofilm.MethodThe inhibiting mechanisms of isookanin against biofilm formation through surface hydrophobicity assay, exopolysaccharides, eDNA, gene expression analysis, microscopic visualization, and molecular docking were explored. Additionally, the combination of isookanin and β-lactam antibiotics were evaluated by the broth micro-checkerboard assay.ResultsThe results showed that isookanin could decrease the biofilm formation of S. epidermidis by ≥85% at 250 μg/mL. The exopolysaccharides, eDNA and surface hydrophobicity were reduced after treatment with isookanin. Microscopic visualization analysis showed that there were fewer bacteria on the surface of the microscopic coverslip and the bacterial cell membrane was damaged after treatment with isookanin. The down-regulation of icaB and up-regulation of icaR were observed after treatment with isookanin. Additionally, the RNAIII gene was significantly up-regulated (p < 0.0001) at the mRNA level. Molecular docking showed that isookanin could bind to biofilm-related proteins. This indicated that isookanin can affect biofilm formation at the initial attachment phase and the aggregation phase. The FICI index showed that the combination of isookanin and β-lactam antibiotics were synergistic and could reduce doses of antibiotics by inhibiting biofilm formation.DiscussionThis study improved the antibiotic susceptibility of S. epidermidis through inhibition of the biofilm formation, and provided a guidance for the treatment of antibiotic resistance caused by biofilm

Antibiofilm activity of polyethylene glycol-quercetin nanoparticles-loaded gelatin-N,O-carboxymethyl chitosan composite nanogels againstStaphylococcus epidermidis

“…The EPS production of S. epidermidis ATCC 35984 treated with blank nanogels, quercetin, and PQ-nanogels was determined as reported elsewhere [ 15 ]. The EPS of S. epidermidis ATCC 35984 (1 × 10 6 CFU/mL) treated with different concentrations (64 and 128 μg/mL) of quercetin and PQ-nanogels were extracted and precipitated using 95% ethanol.…”

“…The eDNA production of S. epidermidis ATCC 35984 treated with blank nanogels, quercetin, and PQ-nanogels was determined, as reported previously [ 15 ]. Briefly, after S. epidermidis ATCC 35984 (1 × 10 6 CFU/mL) was grown in contact with quercetin and PQ-nanogels (64 and 128 μg/mL) at 37°C for 24 h, the samples were washed with PBS, and mixed with a Tris-ethylenediaminetetraacetic acid (EDTA) buffer solution.…”

Nanosystems as Quorum Quenchers Targeting Foodborne Pathogens: Understanding the Inhibition Mechanisms and Their Docking Predictions

“…Moreover, molecular docking can assist in identifying the interaction mechanism of an antibiofilm agent with its target molecule. For instance, a study by Ren [14] showed that isookanin could bind to biofilm-related proteins and interrupt biofilm formation in Staphylococcus epidermis.…”