TDK conference 2024

Antimicrobial resistance is one of the greatest challenges of our time, prompting joint efforts in the fields of veterinary and public health. Members of the Staphylococcus genus is of zoonotic significance, with their role in industrial poultry farming being particularly prominent.

Our objective was to assess the sensitivity profile of commensal Staphylococcus strains isolated from large-scale chicken and turkey flocks in Hungary using minimum inhibitory concentration (MIC) values for nine antibiotics of veterinary and public health importance. In addition to generating frequency tables from the results, we calculated MIC50 and MIC90 values and compared our findings with clinical breakpoints and the EUCAST-defined epidemiological cut-off values (ECOFF). Lastly, we had the opportunity to compare our results with human resistance data.

A total of 227 strains from 23 large-scale chicken farms and 166 strains from 21 large-scale turkey flocks were examined. Correlation analyses between the levels of resistance to different antibiotics showed a strong positive correlation in several cases, but we generally did not detect negative correlations. Cluster analysis and principal component analysis classified the samples into three main clusters. The resistance pattern was minimally influenced by whether the isolates were derived from respiratory or cloacal swabs; however, the purpose of use (chicken vs. turkey) showed significant differences in the resistance levels to most antibiotics. In chickens, the highest resistance was observed against tiamulin (82.8%), followed by doxycycline (74.4%). A similar pattern was seen in turkeys, with tiamulin resistance at 90.4% and doxycycline at 79.5%. When comparing our results with human resistance data, we found that resistance to fluoroquinolones was much higher in veterinary settings (chickens and turkeys) than in human hospitals. The most similar resistance pattern was observed with macrolide antibiotics.

In summary, our findings are in line with several international surveys, although the varying results of different studies may be attributed to differences in antibiotic use across countries. Our results support the justification for regular surveys, as repeated periodic studies allow for the identification of temporal trends. To map the genetic background of multidrug-resistant strains, next-generation sequencing should be considered.