Prävalenz und Quantifizierung ESBL/AmpC-produzierender Enterobacteriaceae bei Masthähnchen während des Schlachtprozesses

- Prevalence and quantification of ESBL/AmpC-producing Enterobacteriaceae in broiler chicken during slaughter - The aim of this study was to determine the prevalence as well as quantitative load of ESBL/AmpC-producing Enterobacteriaceae in different sample matrices (caecum, skin, filet) of seven broiler chicken flocks during slaughter. In addition, environmental samples were taken during slaughter of the respective flocks to gain insights into possible sources of cross contamination with ESBL/AmpC-producing Enterobacteriaceae as well as their possible transmission routes. ESBL/AmpC-producing Enterobacteriaceae were detected during slaughter of all seven investigated flocks. On average, 47 % (83/175) of caecum, 55 % (96/175) of skin, 28 % (49/175) of filet and 28 % (25/89) of environmental samples harboured ESBL/AmpC-producing Enterobacteriaceae. Prevalence varied widely between the flocks as well as between the different sample matrices. However environmental samples of all flocks harboured ESBL/AmpC-producing Enterobacteriaceae. In about half of the caecum and skin samples as well as 85 % (17/20) of the filet samples, the number of cefotaxime resistant Enterobacteriaceae was below quantification limit. The median of cefotaxime resistant Enterobacteriaceae was, depending on sample matrix, 1-4 log units below the median of total Enterobacteriaceae. There was no correlation between the number of total and the number of cefotaxime resistant Enterobacteriaceae in all caecum samples. The median of cefotaxime resistant Enterobacteriaceae was 2.5 x 103 cfu/g in caecum, 1.5 x 103 cfu/g in skin and 1.5 x 102 cfu/g in filet samples. Using real-time PCR, in 82 % (629/767) of the cefotaxime resistant Enterobacteriaceae at least one of the investigated beta-lactamase genes blaCTX-M, blaSHV, blaTEM, blaAmpC-CIT was detected. Prevalence again varied widely between the flocks. In flock 1, 3 and 4 blaAmpC-CIT was, with up to 92 %, the predominant gene, while in flock 5 (84 %) and 6 (42 %) blaSHV was most prevalent. For more than half of the cefotaxime resistant isolates of flock 7 none of the investigated genes could be detected. In this flock, isolates encoding blaCTX-M genes (32 %) were predominant. The respective resistance genes of 322 isolates were further sequenced. The predominant bla gene was blaCMY-2 (48 %), followed by blaSHV-12 (23 %). A contamination from the broiler chicken to the slaughterhouse environment and vice versa seems probable as partially isolates belonging to the same species and phylogroup and encoding the same resistance genes could be detected in all matrices during slaughter of the respective flock as well as in the environment.