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INTRODUCTION. Extended-spectrum beta-lactamase- (ESBL-) and AmpC beta-lactamase enzymes reduce the effectiveness of specific antibiotics. Therefore, ESBL-/AmpC-producing Enterobacteriacae represent an increasing problem, both in human and veterinary medicine. The occurrence of these resistant bacteria in broiler fattening farms is known, however, there are only a few transmission investigations. To elucidate possible transmission routes, we investigated seven different broiler fattening flocks starting with the parent flocks, followed by investigations in the hatchery, the fattening farms and in the slaughterhouse.
MATERIAL AND METHODS. Parent flocks were screened for ESBL-/AmpC-producing Enterobacteriacae as only flocks from positive parents were included. The hatchery as a putative bottleneck for bacterial transmission was investigated for the occurrence of the resistant bacteria on/in the hatching eggs themselves as well as in the environment. After the chick’s hatching the animals of the respective flocks were tracked during the fattening period and finally the carcasses were investigated in the slaughterhouse.
ESBL-/AmpC-producing Enterobacteriacae were isolated and examined for their species, phylogroup and resistance genes. Possible epidemiological relationships of the isolates from the different stages of the production chain will be verified in this ongoing study by pulsed-field gel electrophoresis or whole genome analyses.
RESULTS AND DISCUSSION. In the hatchery, only 0.6% of the investigated samples (n=1,571; eggs and environment) were tested positive for ESBL-/AmpC-producing Enterobacteriaceae. Despite this low incidence at the early stage of the broiler production chain the resistant bacteria occurred in all seven broiler fattening flocks and in the slaughterhouse samples. Molecular analyses showed that the vertical transmission from the hatchery into the broiler fattening farms has a low impact on the spread of ESBL-/AmpC-producing Enterobacteriaceae along the broiler production chain. However, there are indications for horizontal transmission routes of the resistant bacteria through contaminated farm environment. These results will be presented.