Prevalence of extended-spectrum cephalosporinase (ESC)-producing Escherichia coli in Danish slaughter pigs and retail meat identified by selective enrichment and association with cephalosporin usage.
OBJECTIVE
To investigate the prevalence of extended-spectrum cephalosporinase (ESC)-producing Escherichia coli in pigs at slaughter and retail meat, and possible associations with the consumption of third- and fourth-generation cephalosporins.


METHODS
During 2009, faecal samples from Danish pigs (n=786) were collected at slaughter, and 866 meat samples [Danish: pork (153), broiler meat (121) and beef (142); and imported: pork (173), broiler meat (193) and beef (84)] were randomly collected in retail stores and outlets. E. coli was isolated after enrichment in MacConkey broth with ceftriaxone (1 mg/L). ESC genotypes were detected using PCR, microtube array and sequencing. The MIC of cefotaxime was determined for 150 E. coli from the pigs and 606 E. coli from meat isolated without selective enrichment.


RESULTS
Eleven percent (86/786) of slaughter pigs contained ESC E. coli and a significantly higher prevalence was observed among pigs originating from farms with registered cephalosporin consumption in slaughter pigs (P=0.034). Among ESC E. coli from pigs, 66% contained bla(CTX-M-1). From meat, a high prevalence of ESC E. coli was found in imported broiler meat (36%) compared with 0.7%-3.3% in other meat types. ESC E. coli from imported broiler meat (n=69) contained bla(CMY-2) (48%), bla(CTX-M-1) (25%) and bla(SHV-12) (16%). Without selective enrichment, no ESC E. coli from pigs and only 4.1% from imported broiler meat were found.


CONCLUSIONS
The usage of cephalosporins for slaughter pigs may increase the prevalence of ESC E. coli in slaughter pigs. Meat may be a source of ESCs in humans, especially imported broiler meat. Selective enrichment should be considered as a supplementary surveillance method.
Research Group for Microbial Genomics and Antimicrobial Resistance, National Food Institute, Technical University of Denmark, Lyngby, Denmark. yvoa@food.dtu.dk
Yvonne
Y
Agersø
Frank M
FM
Aarestrup
Karl
K
Pedersen
Anne Mette
AM
Seyfarth
Tina
T
Struve
Henrik
H
Hasman
D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D001431:Bacteriological Techniques / Q000379:methods; D002417:Cattle; D002510:Cephalosporinase / Q000235:genetics / Q000378:metabolism*; D002511:Cephalosporins / Q000008:administration & dosage*; D002645:Chickens; D003470:Culture Media / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D003718:Denmark; D004363:Drug Utilization / Q000706:statistics & numerical data*; D004926:Escherichia coli / Q000201:enzymology / Q000254:growth & development / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005243:Feces / Q000382:microbiology; D005838:Genotype; D008460:Meat / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D015995:Prevalence; D017422:Sequence Analysis, DNA; D013552:Swine
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D003470:Culture Media; D004269:DNA, Bacterial; D002510:Cephalosporinase