Antimicrobial resistance is one of the biggest challenges in human and veterinary medicine today. In pigeons, strains of Candida albicans resistant to substances such as clotrimazole, nystatin, or ketoconazole are increasingly being isolated.

Racing pigeons play a key role in spreading resistance, as they travel hundreds of kilometers in a single race, providing an opportunity for resistant bacteria to spread.

Propolis – A Natural Alternative Against Infections

Propolis is a complex natural substance with antibacterial, antiviral, antifungal, antiparasitic, anti-inflammatory, and immunomodulatory properties. Its action is mainly due to polyphenols and terpenoids, bioactive molecules with remarkable therapeutic effects.

The Study: Efficacy of Propolis Against Pathogens

Researchers such as Ádám Kerek and his collaborators evaluated the effectiveness of ethanolic propolis extracts (60%-96%) against pathogens isolated from pigeons:

• Staphylococcus spp
• Enterococcus spp
• Escherichia coli
• Salmonella enterica
• Candida albicans

• Trichomonas gallinae

Thus, propolis was proven effective in inhibiting the growth of bacteria and strains of Candida albicans and Trichomonas gallinae. Its efficacy against Gram-positive bacteria, in some cases, approached that of antibiotics, making propolis a potential alternative in the treatment of wound infections. Its remarkable efficacy against Trichomonas gallinae is promising as a potential alternative for treating this widespread infection in pigeons.

They were also effective against strains of:

• Candida albicans: MIC: 1.56 – 400 µg/mL | MEC: 3.125 – 800 µg/mL
• Trichomonas gallinae: MEC: 2.5 – 5 mg/mL
• Staphylococcus spp.: MIC: 1.56 – 400 µg/mL | MEC: 12.5 – 3260 µg/mL
• Enterococcus spp.: MIC: 1.56 – 400 µg/mL | MEC: 12.5 – 800 µg/mL
• E. coli / Salmonella enterica: MIC > 13,000 µg/mL

Mechanisms of Action

1. Antibacterial:

• Inhibition of nucleic acid synthesis
• Damage to the cell membrane
• Inhibition of biofilm formation and energy metabolism

2. Antifungal (C. albicans):

• Induction of apoptosis
• Inhibition of hyphae formation and cell adhesion
• Disruption of pathogenicity gene expression

3. Antiparasitic (T. gallinae):

• Interference with phospholipid synthesis
• Modification of membrane structure and fluidity
• Cytotoxic effects on mitochondria and hydrogenosome organelle
• Induction of oxidative stress and apoptosis

Special Case – Trichomonas gallinae

This protozoan primarily affects chicks and young birds, causing lesions in the oral cavity and pharynx. The study demonstrated a significant decrease in the number of protozoa after 48-72 hours of exposure to propolis, in some cases leading to complete eradication.

Conclusions

• Propolis has proven effective against drug-resistant pathogens, especially Gram-positive bacteria, C. albicans, and T. gallinae.

• Due to its natural variations, propolis has a lower risk of developing bacterial resistance.

• It can represent a real alternative to antibiotics in the treatment of pigeon infections – topically or via drinking water.

Bibliography

Ádám Kerek, Péter Csanády, Barbara Tuska-Szalay, László Kovács, Ákos Jerzsele. In Vitro Efficacy of Hungarian Propolis against Bacteria, Yeast, and Trichomonas gallinae Isolated from Pigeons—A Possible Antibiotic Alternative Resources, 2023