Factors influencing the activity of tiamulin against Histomonas meleagridis in vitro
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1Institute of Poultry Diseases, Faculty of Veterinary Medicine, Free University Berlin, Königsweg 63, 14163 Berlin, Germany.
Abstract:
In this study, we investigated the activity of tiamulin fumerate against three strains of Histomonas meleagridis in vitro under different conditions. Tiamulin reduced histomonal growth of all three strains at concentrations of 20 ppm and higher. Cultures in phosphate-buffered saline-based medium were more susceptible than cultures in traditional Dwyers medium. When the cultures were inoculated with higher numbers of histomonads, the activity of tiamulin was reduced. Bacteria present in the cultures were resistant against tiamulin.
Insights
Tiamulin fumarate effectively inhibited the growth of Histomonas meleagridis strains in vitro. Its efficacy was higher in phosphate-buffered saline medium and reduced with increased parasite numbers or bacterial presence.
Area of Science:
- Veterinary Parasitology
- Antimicrobial Drug Efficacy
- Poultry Health
Background:
- Histomonas meleagridis causes blackhead disease, a significant threat to poultry health.
- Limited effective treatments are available for histomoniasis.
- Tiamulin is a pleuromutilin antibiotic used in veterinary medicine.
Purpose of the Study:
- To evaluate the in vitro activity of tiamulin fumarate against three strains of Histomonas meleagridis.
- To determine the influence of different culture media and inoculation densities on tiamulin efficacy.
- To assess the susceptibility of co-infecting bacteria to tiamulin.
Main Methods:
- In vitro culture of three Histomonas meleagridis strains.
- Testing tiamulin fumarate at various concentrations (≥20 ppm).
- Comparison of growth inhibition in phosphate-buffered saline-based medium versus Dwyers medium.
- Evaluation of high-inoculum density effects and bacterial resistance.
Main Results:
- Tiamulin fumarate demonstrated inhibitory effects on all three H. meleagridis strains at concentrations of 20 ppm and higher.
- Cultures in phosphate-buffered saline-based medium showed greater susceptibility to tiamulin compared to Dwyers medium.
- Higher initial parasite loads reduced tiamulin's inhibitory activity, and co-present bacteria were resistant to tiamulin.
Conclusions:
- Tiamulin fumarate exhibits significant in vitro activity against Histomonas meleagridis.
- Culture medium composition and parasite load are critical factors influencing tiamulin efficacy.
- Tiamulin is not effective against bacteria commonly found in H. meleagridis cultures.
