title: The new allelic variant of the subtilase cytotoxin (subAB2) is common among Shiga toxin-producing Escherichia coli strains from large game animals and their meat and meat products.
abstract: Subtilase cytotoxin (SubAB) is an AB5 toxin produced by Shiga toxin (Stx)-producing Escherichia coli (STEC) strains usually lacking the eae gene product intimin. Two allelic variants of SubAB encoding genes have been described: subAB1, located on a plasmid, and subAB2, located on a pathogenicity island (PAI) together with tia gene. While subAB1 has been reported to be more frequent among bovine strains, subAB2 has been mainly associated with strains from small ruminants. We investigated the presence of the two variants of subAB among 59 eae-negative STEC from large game animals (deer and wild boar) and their meat and meat products in order to assess the role of other species in the epidemiology of subAB-positive, eae-negative STEC. For this approach, the strains were PCR-screened for the presence of subAB, including the specific detection of both allelic variants, for the presence of saa, tia and sab, and for stx subtyping. Overall, subAB genes were detected in 71.2% of the strains: 84.1% of the strains from deer and 33.3% of the strains from wild boar. Most of them (97.6%) possessed subAB2 and most of these subAB2-positive strains (92.7%) were also positive for tia and negative for saa, suggesting the presence of the subAB2-harbouring PAI. Subtype stx2b was present in most of the strains (67.8%) and a statistically significant association could be established between subAB2 and stx2b. Our results suggest that large game animals, mainly deer, may represent an important animal reservoir of subAB2-positive, eae-negative STEC, and also highlight the risk of human infection posed by the consumption of large game meat and meat products.
authors.affiliation: Unidad de Enterobacterias, Servicio de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Madrid, Spain. sergio.sanchez@isciii.es
authors.forename: Sergio
authors.initials: S
authors.lastname: Sánchez
authors.forename: Sandra
authors.initials: S
authors.lastname: Díaz-Sánchez
authors.forename: Remigio
authors.initials: R
authors.lastname: Martínez
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Llorente
authors.forename: Silvia
authors.initials: S
authors.lastname: Herrera-León
authors.forename: Dolors
authors.initials: D
authors.lastname: Vidal
mesh_terms: D000483:Alleles; D000818:Animals; D003670:Deer / Q000382:microbiology*; D004197:Disease Reservoirs / Q000382:microbiology*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary; D029968:Escherichia coli Proteins / Q000235:genetics*; D005506:Food Contamination / Q000032:analysis; D044404:Genomic Islands; D006801:Humans; D008460:Meat / Q000382:microbiology*; D008461:Meat Products / Q000382:microbiology; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D013381:Subtilisins / Q000235:genetics*; D034421:Sus scrofa / Q000382:microbiology*; D013552:Swine
chemical_list: D029968:Escherichia coli Proteins; D013381:Subtilisins; C527234:subtilase cytotoxin, E coli
keywords: Allelic variants; Deer; STEC autotransporter contributing to biofilm formation (Sab); Shiga toxin-producing Escherichia coli (STEC); Subtilase cytotoxin (subAB); Wild boar