TDK conference 2020

E. coli is an extremely common facultative pathogen in the intestinal tract of poultry and humans. In recent years, resistance to antibiotics in human medicine has become more widespread in E. coli strains, and animal husbandry treatments are contributing to this. The bacterium is able to transfer genes responsible for resistance horizontally (via plasmids), allowing them to appear in other pathogenic microbes.

The aim of our studies is to assess the current state of the susceptibility of E. coli strains of Hungarian poultry flocks to an antibiotic, enrofloxacin, which is also important in human medicine, and to develop a method for measuring redox potential for rapid assessment of resistance.

E. coli strains were isolated from commercially available chicken meat on TBX medium containing various concentrations of enrofloxacin. Isolated strains were tested in broth containing enrofloxacin by redox potential measurement, which is suitable for detecting the changes in microbial activity in the presence of an inhibitor. The results obtained were compared with the evaluation determined by the disk diffusion method.

Some isolates were able to proliferate in the broth in the presence of even up to 4000 times of the MIC value of 0.05 μg/ml from the literature data. Additional studies with enrofloxacin-resistant bacteria were performed to investigate the susceptibility of amoxicillin and doxycycline, several of which showed multidrug resistance.

Nearly 10% (9.3%) of E. coli strains isolated from chicken meat delivered to consumers survived the 1000-fold literature MIC (50 μg/ml) enrofloxacin concentration. Although this microbe is killed during normal kitchen technology operations, there is a possibility that resistant E. coli will enter the consumer's body through smear contamination or that these resistance genes may be transferred to other pathogenic microbes during horizontal gene transfer.

The project is supported by the European Union, co-financed by the European Social Fund (ESF) (grant agreement number: EFOP-3.6.3-VEKOP-16-2017-00005, title: Strengthening the scientific supply by supporting students' scientific workshops and programs, by developing the mentoring process).