TDK conference 2024

One of the greatest challenges of our time is the global spread of antimicrobial resistance, which prompts professionals in both veterinary and public health to collaborate and think collectively. Clostridium perfringens continues to cause significant economic losses in the poultry industry, and its commensal strains can naturally harbor and maintain not only resistance genes but also genes responsible for toxin production.

Our goal was to assess the antimicrobial susceptibility profiles of commensal Clostridium perfringens strains isolated from large-scale turkey farms in Hungary, using minimal inhibitory concentration (MIC) determination against key substances of veterinary and public health importance. We complemented our study with PCR analysis to detect the presence of major and minor toxin genes specific to the species, and we explored potential correlations between the presence of these genes and the antimicrobial resistance profiles.

A total of 146 commensal strains isolated from turkeys were tested against 14 antimicrobial agents, six of which had clinical breakpoints. We calculated the MIC50 and MIC90 values for the tested population: both values were below the clinical breakpoint for imipenem, but only the MIC50 value was below the breakpoint for amoxicillin and clindamycin. Sensitivity to penicillin, which has long been used to treat infections caused by Clostridium perfringens, decreased, with only 44.5% of strains showing sensitivity, whereas 87.7% of the strains were sensitive to amoxicillin. The lowest sensitivity was observed against lincomycin, with only 11.6% of the strains being susceptible.

All of the tested strains were positive for the major alpha toxin gene, with 23.9% carrying the major beta gene, 15.8% carrying the minor beta2 gene, 3.4% carrying the minor netB gene, and 2.7% carrying the major epsilon gene. However, no correlation was found between the presence of toxin genes and the antimicrobial susceptibility profiles, as statistical analysis did not reveal significant differences between MIC values and the presence or absence of toxin genes.

In conclusion, Clostridium perfringens strains have retained their sensitivity to the beta-lactam antibiotics, which are the primary treatment option, and regular monitoring can help establish long-term trends. In the future, it would be beneficial to repeat the study with a larger sample size and to further investigate the multi-resistant strains using next-generation sequencing.