Isolation and characterization of non-O157 Shiga toxin-producing Escherichia coli from carcasses, anatomical cuts and trimmings of abattoirs in Argentina

LEOTTA GA; BRUSA V; RESTOVICH V; GALLI L; TEITELBAUM D; PADOLA NL; BRASESCO H; ORTEGA EE; GARCÍA D; LINARES LH; PETROLI S; LONDERO A; BRUZZONE M; DE LA TORRE JH; SUPERNO V; SUBERBIE G; FERREGHINI M; SIGNORINI M

Boston

Simposio; 9th International Symposium on Shiga Toxin Producing Escherichia coli; 2015

ASM

Several food contaminated with Shiga toxin-producing Escherichia coli (STEC) were associated with human diseases. In some countries a microbiological criteria for non-O157 STEC was established. The absence of O26, O45, O103, O104, O111, O121 and O145 serogroups in sprouts (EU) or ground beef and beef trim (USA) is mandatory. Although, in another countries the zero-tolerance approach to all STEC has been proposed for chilled beef. The aim of this study was to establish the frequency of non-O157 STEC on carcasses, anatomical cuts and trimmings in eight abattoirs from Argentina. Between March and September 2014, 15.965 samples were collected, including 3.205 carcasses, 9.570 anatomical cuts and 3.190 trimmings. The samples were processed in pools of five samples each. A total of 3.193 pools of samples (642 carcasses, 1.914 anatomical cuts and 638 trimming) were analyzed for non-O157 STEC according ISO/CEN 13136:2012. Thirty-nine (6.1%) pools of carcasses, 111 (5.8%) pools of anatomical cuts, and 45 (7.0%) pools of trimmings were positive for non-O157 STEC. A total of 208 STEC strains were isolated from 195 (6.1%) pools of samples. The most prevalent serotypes were O174:[H21,H28,NT], O185:[H7,NT], O8:[H16,H19,NT], O178:[H19,NT], O130:[H11,NT], and O39:[H49,NT]. The most frequent genotypes were stx2c(vh-b) (20.0%), stx2/saa (16.4%), stx2 (15.9%), stx1c(vh-a)/stx2/saa (10.2%), stx2a (8.7%), and stx1a/saa (8.2%). Only one isolate was O103:NT stx/eae-positive. The results obtained showed a low frequency (6.1%) of non-O157 STEC through beef chain production, and without the eae or aggR/aaiC gene. However, there is insufficient data to associate the presence of a particular combination of virulence genes and/or serogroup to a particular disease outcome. The zero-tolerance approach is very difficult to implement through chilled beef processing. It is necessary to reinforce the surveillance of human diseases caused by non-O157 STEC to clearly identify the biohazard, in order to mitigate the risk in abattoirs.