The Anti-Staphylococcal Potential of Ethanolic Polish Propolis Extracts.

Katarzyna Grecka,Justyna Walkusz,Randy W Worobo,Piotr Okińczyc,Piotr Szweda,Piotr M Kuś

doi:10.3390/molecules24091732

Abstract

The principal objective of this study was to determine the anti-staphylococcal potential of ethanol extracts of propolis (EEPs). A total of 20 samples of propolis collected from apiaries located in different regions of Poland were used in the study. The two-fold broth microdilution method revealed some important differences in the antimicrobial activity of investigated EEPs. Up to the concentration of 4096 µg/mL no activity was observed against Gram-negative bacteria (E. coli and P. aeruginosa). Staphylococci exhibited much higher susceptibility. The highest efficiency observed for EEP12 and EEP20 (MIC values ranged between 32 and 256 µg/mL). However, the achievement of bactericidal effect usually required higher concentrations. In the case of clinical isolates of S. aureus MBC values for EEP12 and EEP20 ranged from 512 to 1024 µg/mL. The HPLC analysis revealed that these two products contained a higher concentration of flavonoids (flavonols, flavones, and flavanones) compared to other investigated EEPs. In checkerboard test, a synergistic anti-staphylococcal effect was observed for the action of EEP20 in combination with amikacin, kanamycin, gentamycin, tetracycline, and fusidic acid (all these antibiotics inhibit protein synthesis). Moreover, the investigated EEPs effectively eradicated staphylococcal biofilm. The obtained results clearly confirm the high anti-staphylococcal potential of propolis harvested in Polish apiaries.

Highlights

Based on the World Health Organization reports, the resistance of bacteria to well-known antibiotics is becoming a major global health challenge [1]
The highest susceptibility was exhibited by S. epidermidis ATCC 12228, with minimum inhibitory concentrations (MICs) and minimal bactericidal concentration (MBC) values in the range of concentrations between μg/mL and 512 μg/mL
In line with focused our attention on the antibacterial, primarily anti-staphylococcal, activity of ethanolic extracts this tendency, we have focused our attention on the antibacterial, primarily anti-staphylococcal, of honey bee propolis (EEPs), collected in apiaries located in different regions of Poland

Summary

Introduction

Based on the World Health Organization reports, the resistance of bacteria to well-known antibiotics is becoming a major global health challenge [1]. One of the groups of bacteria which have evolved mechanisms of resistance to a plethora of antibiotics currently in use for human and animal therapies are staphylococci, Staphylococcus aureus. They are responsible for a broad spectrum of difficult to treat diseases including skin and ocular infections, foodborne illness, pneumonia, meningitis, endocarditis, and osteomyelitis. High pathogenicity of S. aureus is based on the production of a wide array of virulence factors that include protein A, coagulase, collagenase, hyaluronidase, hemolysins, lipases, different toxins, adhesive proteins and proteins affecting the biofilm formation These bacteria are very ubiquitous in the environment. Due to the growing frequency of isolation of staphylococcal strains resistant to currently used antibiotics, their high virulence potential and common

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