Polyethyleneimine and polyethyleneimine-based nanoparticles: novel bacterial and yeast biofilm inhibitors

Abstract

Biofilms are commonly involved in medical device-related infections. The purpose of this study was to determine the antimicrobial and anti-biofilm activity of polyethyleneimine (PEI) and PEIbased nanoparticles (nanoPEI) against Staphylococcus aureus, Staphylococcus epidermidis, Acinetobacter baumannii and Candida albicans (clinical and ATCC strains), and to evaluate their effect upon biofilm formation on polyurethane (PUR)-like catheters. MICs and minimal lethal concentrations of PEI and nanoPEI were determined according to CLSI microdilution reference protocols. For PEI, the MIC value was 195.31 mg l "1 for all the bacteria and 48.83 mg l "1 for the yeast strains. For nanoPEI, the MIC value was 1250 mg l "1 for all the strains except A. baumannii, for which it was 2500 mg l "1. Biofilm formation was assessed with PUR-like catheter segments and biofilm metabolic activity was quantified by colorimetry with a tetrazolium reduction assay. Plasma membrane integrity and membrane potential were assessed by flow cytometry after staining microbial cells with a membrane-impermeable dye, propidium iodide, and a membranepotential marker, DiBAC 4 (3). PEI inhibited growth of all microbial species; higher concentrations of nanoPEI were needed to inhibit growth of all species. Biofilm formation in the presence of antibacterial PEI activity was dose-dependent (except for S. epidermidis) and species-related. NanoPEI at 0.5¾MIC and MIC significantly reduced the metabolic activity of biofilms of S. aureus, S. epidermidis and A. baumannii, whereas 2¾MIC was required in order to inhibit biofilm metabolic activity.

Essential Oils and Their Components as Modulators of Antibiotic Activity against Gram-Negative Bacteria

“…Immortelle ( Helichrysum italicum (Roth) G. Don., Asteraceae) EO reduced the resistance to chloramphenicol of A. baumannii ATCC 19606 and the AB1 strain isolated from central venous catheters of critical care patients [37,38]. In the case of both strains, immortelle EO reduced by eight-fold the MIC value of chloramphenicol in combination, whereas phenylalanine-arginine β-naphthylamide (PaβN), a potent efflux pumps inhibitor, caused only a two-fold reduction.…”

Nanomaterials for alternative antibacterial therapy

“…The effectiveness of Ag NPs is also augmented with compounds such as polyethyleneimines, chitosan and glucosamine that serve as ligands and reinforce their uptake into bacterial cells. 128 Chitosan has inherent antimicrobial properties due its polycationic character. Low-molecular weight chitosan-coated Ag NPs have been reported to surpass polyvinylpyrrolidone-coated Ag NPs and Ag NPs without surface stabilizer (uncoated Ag NPs) in efficacy against MRSA with enhanced biocompatibility and reduced body absorption characteristics.…”

Synthesis and Antimicrobial Activity of a New Series of Thiazolidine-2,4-diones Carboxamide and Amino Acid Derivatives

“…Indeed, the antimicrobial assay revealed that most of compounds tested had no or negligible activity against S. aureus and B. subtilis with the exception of some acid derivatives (3a, 3b, and 3g). This observation could be explained by the difference in the cell wall structure of Gram-positive and Gram-negative bacteria or it may be due to the charges and the kinetics of the chemical compounds, which can damaged the bacterial cell wall via electrostatic interactions, as previously reported by Azevedo et al [39].…”