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

OBJECTIVES: To determine the prevalence of extended-spectrum ß-lactamase (ESBL) production in Enterobacteriaceae 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 bla(TEM), bla(CTX-M) and bla(SHV) 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 (n = 82), CTX-M-1 (n = 77) and TEM-52 (n = 16). 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 coresistance to different classes of antibiotics in the ESBL producers might reflect the common veterinary usage of these and related substances. There is an urgent need to further evaluate the role of poultry in the transmission of highly resistant ESBL-producing bacteria in humans.

Improved glycosylation of a foreign protein by Tn-5B1-4 cells engineered to express mammalian glycosyltransferases.

The major advantages of using the baculovirus-insect cell system for recombinant protein production are its ability to produce large amounts of recombinant proteins and its ability to provide eucaryotic modifications, such as glycosylation. However, the glycans linked to recombinant glycoproteins produced by this system typically differ from those found on native mammalian products. This is an important problem because glycans on mammalian glycoproteins can influence their functions in many different ways. The inability of baculovirus-infected insect cells to produce glycans identical to those found on native mammalian glycoproteins is due, in part, to the absence of functional levels of certain glycosyltransferases in insect cells. Thus, the purpose of this study was to engineer these activities into Tn-5B1-4, an established insect cell line that is widely used as a host for baculovirus-mediated protein production. Expression plasmids were constructed in which cDNAs encoding mammalian beta1,4-galactosyltransferase and alpha2,6-sialyltransferase were placed under the transcriptional control of a baculovirus immediate early promoter. These plasmids were then used to isolate two different transgenic Tn-5B1-4 derivatives and the biological and biochemical properties of these cell lines were examined. The results show that both of the engineered insect cell lines have improved glycoprotein-processing capabilities, relative to the parental cell line.