Cationic chitosan-propolis nanoparticles alter the zeta potential of S. epidermidis, inhibit biofilm formation by modulating gene expression and exhibit synergism with antibiotics

Abstract

Staphylococcus epidermidis , is a common microflora of human body that can cause opportunistic infections associated with indwelling devices. It is resistant to multiple antibiotics necessitating the need for naturally occurring antibacterial agents. Malaysian propolis, a natural product obtained from beehives exhibits antimicrobial and antibiofilm properties. Chitosan-propolis nanoparticles (CPNP) were prepared using Malaysian propolis and tested for their effect against S . epidermidis . The cationic nanoparticles depicted a zeta potential of +40 and increased the net electric charge (zeta potential) of S . epidermidis from -17 to -11 mV in a concentration-dependent manner whereas, ethanol (Eth) and ethyl acetate (EA) extracts of propolis further decreased the zeta potential from -17 to -20 mV. Confocal laser scanning microscopy (CLSM) depicted that CPNP effectively disrupted biofilm formation by S . epidermidis and decreased viability to ~25% compared to Eth and EA with viability of ~60–70%. CPNP was more effective in reducing the viability of both planktonic as well as biofilm bacteria compared to Eth and EA. At 100 μg/mL concentration, CPNP decreased the survival of biofilm bacteria by ~70% compared to Eth or EA extracts which decreased viability by only 40%-50%. The morphology of bacterial biofilm examined by scanning electron microscopy depicted partial disruption of biofilm by Eth and EA extracts and significant disruption by CPNP reducing bacterial number in the biofilm by ~90%. Real time quantitative PCR analysis of gene expression in treated bacteria showed that genes involved in intercellular adhesion such as IcaABCD , embp and other related genes were significantly downregulated by CPNP. In addition to having a direct inhibitory effect on the survival of S . epidermidis , CPNP showed synergism with the antibiotics rifampicin, ciprofloxacin, vancomycin and doxycycline suggestive of effective treatment regimens. This would help decrease antibiotic treatment dose by at least 4-fold in combination therapies thereby opening up ways of tackling antibiotic resistance in bacteria.

Propolis nanoparticle enhances the potency of antimicrobial photodynamic therapy against Streptococcus mutans in a synergistic manner

“…However, on treatment with the PhotoActive + -or TBO-aPDT plus , a considerable down-regulation compared to the previous state was detected in all the examined genes. Ong et al 21 , whose study demonstrate that the propolis affects gene expression and makes it more sensitive to treatment with antibiotics. Also, the results of the present study showed that gtfC was more affected in the combination-treatment group than the other genes tested.…”

“…Propolis as a natural product collected by bees from various parts of plant sources is known to possess pharmacological activities, including anti-inflammatory, anticancer, antioxidant, antifungal, antiviral and antimicrobial effects 21 . Propolis nanoparticles (PNPs) are more effective in treatment because particle size decreases and the surface/volume ratio become too large.…”

Multi Dynamic Extraction: An Innovative Method to Obtain a Standardized Chemically and Biologically Reproducible Polyphenol Extract from Poplar-Type Propolis to Be Used for Its Anti-Infective Properties

“…The addition of propolis to a rubber mixture made the material resistant to thermo-oxidative aging and ozone and protected it from biodegradation [53]. As for the new and interesting field of nanomaterials, chitosan–propolis nanoparticles, prepared using propolis from Asia, exhibited the abilities to alter the zeta potential of S. epidermidis , inhibit biofilm formation by modulating gene expression, and synergize with antibiotics [54]. Propolis/polyurethane composite nanofibers and electrospun materials have been proposed for biomedical applications [55].…”

<p>Synergistic Nanocomposites of Different Antibiotics Coupled with Green Synthesized Chitosan-Based Silver Nanoparticles: Characterization, Antibacterial, in vivo Toxicological and Biodistribution Studies</p>

“…Recently, several studies reported the synergistic antibacterial activities of different antibiotics after combinations with different metallic nanoparticles. [16][17][18][19][20] Some studies have described the reduction in the cytotoxicity of antimicrobial compounds after conjugations. 21,22 However, the potential in vivo toxicity and tissue distribution of these synthesized and conjugated silver nanoparticles have not yet been investigated.…”