Synergistic Effect of Polyphenol-Rich Complex of Plant and Green Propolis Extracts with Antibiotics against Respiratory Infections Causing Bacteria

Abstract

Bacterial infections are a prevalent complication after primary viral respiratory infections and are associated with high morbidity and mortality. Antibiotics are widely used against bacterial respiratory pathogens; however, the rise in antibiotic-resistant strains urges us to search for new antimicrobial compounds, including ones that act synergistically with antibiotics. In this study, the minimal inhibitory (MIC) and minimal bactericidal (MBC) concentrations of a polyphenol-rich complex of green propolis, Tabebuia avellanedae bark, and Olea europaea leaf extracts against Staphylococcus aureus, Haemophilus influenzae, and Klebsiella pneumoniae were determined, followed by an analysis of the synergistic effect with clarithromycin, azithromycin, and amoxiclav (875/125 mg amoxicillin/clavulanic acid). A combination of extracts showed activity against all three bacterial strains, with MIC values ranging from 0.78 to 12.5 mg/mL and MBC values from 1.56 to 12.5 mg/mL. The extracts showed synergistic activity with azithromycin and clarithromycin against S. aureus, with clarithromycin against K. pneumoniae, and with all three tested antibiotics against H. influenzae. Synergy with clarithromycin was additionally evaluated in a time-kill assay where the synergistic effects against S. aureus and K. pneumoniae were seen within the first 6 h of incubation. The results show the potential of polyphenol-rich extracts in enhancing the efficacy of antibiotic therapy and indicate their potential to be used in the management of respiratory infections.

Edible Xanthan/Propolis Coating and Its Effect on Physicochemical, Microbial, and Sensory Quality Indices in Mackerel Tuna (Euthynnus affinis) Fillets during Chilled Storage

“…Among these phenolic compounds is gallic acid, known for its antibacterial activity [ 55 ]. Phenolic compounds act on the bacterial cell membrane, interfere with nucleic acid synthesis, inhibit bacterial metabolism, coagulate cytoplasmic proteins, and interfere with biofilm formation [ 56 ].…”

Perspectives for Uses of Propolis in Therapy against Infectious Diseases

“…Propolis possesses a strong and multi-targeted antibacterial activity, chiefly attributed to its flavonoids. A study with positive results evaluated the synergy between antibiotics and a polyphenol-rich mix composite with plants and propolis extracts [ 155 ].…”

Phytochemical screenings, antibacterial and anti-biofilm activities of Garcinia cowa Roxb. leaves extracts and its synergistic effect with antibiotic

“…Antibiotic resistance impairs the ability to treat diseases and infection in humans. Recently, antibacterial effect of plant extracts or natural compounds is found to be synergistic with several antibiotics like ciprofloxacin, tetracycline, gentamycin, etc [11][12][13] . According to the World Health Organization (WHO), around 80% of the population in developing countries use traditional medicine as primary source of healthcare.…”