High prevalence of extended-spectrum-b-lactamase-producing Enterobacteriaceae in organic and conventional retail chicken meat, Germany

Objectives: To determine the prevalence of extended-spectrum b-lactamase (ESBL) production in Enterobac-teriaceae in retail chicken meat in Germany. Methods: A total of 399 chicken meat samples from nine supermarket chains, four organic food stores and one butcher’s shop in two geographically distinct regions (Berlin and Greifswald) were screened for ESBL production using selective agar. Phenotypic ESBL isolates were tested for blaTEM, blaCTX-M and blaSHV genes using PCR and DNA sequencing. Antibiotic coresistances were determined and strain typing was performed using PCR-based phylogenetic grouping and XbaI-PFGE. Results: A total of 185 confirmed ESBL isolates were obtained from 175 samples (43.9%) from all tested sources. The majority of isolates were Escherichia coli producing ESBL types SHV-12 (n82), CTX-M-1 (n77) and TEM-52 (n16). No differences could be observed in the prevalence of ESBL producers between organic and conventional samples. 73.0 % of the ESBL producers showed coresistance to tetracycline, 35.7 % to co-trimoxazole and 7.6 % to ciprofloxacin. Strain typing of selected E. coli isolates from Berlin revealed identical macrorestriction patterns for several isolates from samples taken from the same stores. Conclusions: This is the first comprehensive study from Germany showing a high prevalence of TEM-, CTX-M- and SHV-type ESBLs in Enterobacteriaceae isolated from retail chicken meat. The high rate of coresis