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Výskyt antibiotické rezistence u bakteriálních kmenů izolovaných z výkalů selat po odstavu
Plevák, Petr
The most significant economic losses in breeding of weaned piglets cause bacterial infectious diseases. The antimicrobial agents are used to combat and control infections. Moreover, antibiotics are still utilized as growth promoters at lower concentrations in some countries. With the increasing incidence of resistant bacterial strains, including human medicine, the use of antibiotics has been limited and controlled in the European Union. Similar antimicrobial effects are provided by zinc oxide, which is used today in prevention instead of prohibited antibiotics. However, high concentrations of zinc get into the environment along with slurry and contaminate the soil. Currently, new forms of zinc nanoparticles have been developed to decrease the effective zinc concentrations utilized in agriculture. The experimental part of this thesis includes 3 experimental groups of weaned piglets. The first group was control group (basal diet), the second was supplemented by zinc oxide and the third group was treated by zinc nanoparticles supplements. These groups were subdivided according to the concentration of zinc compound (500, 1000 and 2000 mg.kg-1) and each group contained 10 piglets. Feces samples were collected on 0th, 5th, 10th and 20th day of the experiment. 224 bacterial strains were isolated from these samples and identified as Escherichia coli, a potential causative agent of coliform infections. The disc diffusion method was used to determine the susceptibility/resistance to the most common antibiotics employed in Czech animal husbandry and also to the important antibiotics of human medicine. The best results (the highest efficiency) were achieved by ciprofloxacin, ceftazidime, imipenem, cefotaxime and colistin. The most frequent incidence of resistant strains were found for chlortetracycline, ampicillin and amoxicillin. Moreover, 2 isolates were evaluated as producers of extended-spectrum β-lactamases by testing with combination of ceftazidime/clavulanic acid and 5 isolates by testing with combination of cefotaxime/clavulanic acid. The comparison of resistant strains incidence across the experimental groups, did not show an induction of antimicrobial resistance in association with dietary administration of zinc nanoparticles in feed mixtures.
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