Verocytotoxigenic Escherichia coli O157 in beef and sheep abattoirs in Ireland and characterisation of isolates by Pulsed-Field Gel Electrophoresis and Multi-Locus Variable Number of Tandem Repeat Analysis.
This study aimed to investigate verocytotoxigenic Escherichia coli O157 in the largest beef and sheep slaughter plants in Ireland over a one-year period. Samples consisted of pooled rectal swabs (n=407) and pooled carcass swabs (n=407) from 5 animals belonging to the same herd or flock and minced meat (n=91) from the same sampling date. E. coli O157 isolates were characterised using PCR for a range of genes, i.e. 16S, rfbE, fliC, vtx1, vtx2, eaeA and confirmed VTEC O157 isolates were tested for antimicrobial susceptibility and typed using Pulsed-Field Gel Electrophoresis (PFGE) and Multi-Locus Variable Number of Tandem Repeat Analysis (MLVA). VTEC O157 was isolated from 7.6% and 3.9% of bovine rectal and carcass swab samples and from 5.8% and 2.9% of ovine rectal and carcass swab samples respectively. None of the bovine minced meat samples (n=77) and only one of the 14 ovine minced meat samples was positive for VTEC O157. Following PFGE and MLVA, cross contamination from faeces to carcasses was identified. While PFGE and MLVA identified the same clusters for highly related strains, MLVA discriminated better than PFGE in addition to being more rapid and less labour intensive. Results showed that cattle and sheep presented for slaughter in Ireland harbour VTEC O157, and although the levels entering the food chain are low, this should not be overlooked as possible sources of zoonotic infection; molecular typing was able to demonstrate relationships among strains and could be used to elucidate the sources of human infection.
National Reference Laboratory for Escherichia coli (Food, Feed and Animal Health) Department of Agriculture, Fisheries and Food, Backweston Complex, Celbridge, Co. Kildare, Ireland.
Deirdre M
DM
Prendergast
Lynsey
L
Lendrum
Rachel
R
Pearce
Caroline
C
Ball
Joanne
J
McLernon
Don
D
O'Grady
Lourda
L
Scott
Seamus
S
Fanning
John
J
Egan
Montserrat
M
Gutierrez
D000003:Abattoirs; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D002417:Cattle; D016521:Electrophoresis, Gel, Pulsed-Field; D019453:Escherichia coli O157 / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D005516:Food Microbiology; D007494:Ireland; D008460:Meat / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D018598:Minisatellite Repeats; D010802:Phylogeny; D012007:Rectum / Q000382:microbiology; D012756:Sheep
D000890:Anti-Infective Agents