Detection of Shiga-Like Toxin-Producing Escherichia coli in Ground Beef and Milk by Commercial Enzyme Immunoassay

Abstract

Shiga-like toxin (SLT)-producing Escherichia coli (SLTEC) is the leading cause of acute renal failure among children. SLTEC are most commonly ingested from contaminated food, and because cattle are a major reservoir, ground beef and milk have been a significant source of contamination associated with multiperson outbreaks. While serotype O157:H7 has been principally identified in the United States there are many other SLTEC serotypes associated with human disease. We have therefore examined the utility of an enzyme immunoassay (EIA) for Shiga-like toxins as a means of detecting the presence of low levels of multiple SLTEC serotypes in ground beef and milk. In the present study we demonstrated that it is possible to detect low levels (approximately 1 SLTEC per g of ground beef) in both small-scale (2 g of beef per 5 ml) and standard large-scale (25 g of beef per 225 ml) food microbial cultures. The EIA was also capable of allowing detection of SLTEC in nonspiked retail ground beef samples: we were able to recover SLTEC isolates (O113:Hu; O22:H-; O82:H8) from 3 of 12 ground beef samples. The EIA detected SLTs produced in spiked milk samples when as few as 1 SLTEC per ml was added. Overall the EIA proved to be a highly sensitive way to detect the presence of SLTEC in either ground beef or milk samples after overnight enrichment culturing in an appropriate broth and should provide a rapid and convenient method for the detection of multiple pathogenic SLTEC serotypes.

Survival of pathogenic enterohemorrhagic Escherichia coli (EHEC) and control with calcium oxide in frozen meat products

“…These results imply that EHEC is one of the major sources of beef contamination, unlike the other pathogenic E. coli. National surveys have also observed STEC in raw or ground beef at rates ranging from 15% to 25% (Acheson et al, 1996;Samadpour et al, 2002;Adwan and Adwan, 2004). In contrast, the prevalence rates in ground beef from other previous studies showed lower values than the range observed in our study.…”

Shiga Toxin–ProducingEscherichia coliin Montana: Bacterial Genotypes and Clinical Profiles

“…In this regard, it is noteworthy that, in several studies that attempted to address the pathogenicity of non-O157:H7 STEC, control subjects without diarrhea had the same frequency of fecal excretion of non-O157:H7 STEC as did patients with diarrhea [51][52][53][54][55]. Non-O157:H7 STEC are quite common in food [56,57], in contrast to the comparative rarity of O157:H7 STEC [58]. Thus, human contact with non-O157:H7 STEC is probably frequent, and it is possible that, in some patients, the recovery of non-O157:H7 STEC in the stool reflects innocuous gastrointestinal pass-though and not infection.…”

Phenotypic and genotypic characterization of sorbitol-negative or slow-fermenting (suspected O157) Escherichia coli isolated from milk samples in Lombardy region

“…Rapid methods able to identify E. coli O157:H7 in foods or faecal specimens are directed towards immunological or genetic targets. Although immunoassays are more rapid and less labour intensive than cultural techniques (Acheson et al 1996), they are inadequate as independent procedures. Furthermore, false positives are not uncommon when interpreting immunoassay test results, and further confirmation is required.…”