Presence and Characterization of Shiga Toxin-Producing Escherichia coli and Other Potentially Diarrheagenic E. coli Strains in Retail Meats

Abstract

To determine the presence of Shiga toxin-producing Escherichia coli (STEC) and other potentially diarrheagenic E. coli strains in retail meats, 7,258 E. coli isolates collected by the U.S. National Antimicrobial Resistance Monitoring System (NARMS) retail meat program from 2002 to 2007 were screened for Shiga toxin genes. In addition, 1,275 of the E. coli isolates recovered in 2006 were examined for virulence genes specific for other diarrheagenic E. coli strains. Seventeen isolates (16 from ground beef and 1 from a pork chop) were positive for stx genes, including 5 positive for both stx 1 and stx 2 , 2 positive for stx 1 , and 10 positive for stx 2 . The 17 STEC strains belonged to 10 serotypes: O83:H8, O8:H16, O15:H16, O15:H17, O88:H38, ONT:H51, ONT:H2, ONT:H10, ONT:H7, and ONT:H46. None of the STEC isolates contained eae, whereas seven carried enterohemorrhagic E. coli (EHEC) hlyA. All except one STEC isolate exhibited toxic effects on Vero cells. DNA sequence analysis showed that the stx 2 genes from five STEC isolates encoded mucus-activatable Stx2d. Subtyping of the 17 STEC isolates by pulsed-field gel electrophoresis (PFGE) yielded 14 distinct restriction patterns. Among the 1,275 isolates from 2006, 11 atypical enteropathogenic E. coli (EPEC) isolates were identified in addition to 3 STEC isolates. This study demonstrated that retail meats, mainly ground beef, were contaminated with diverse STEC strains. The presence of atypical EPEC strains in retail meat is also of concern due to their potential to cause human infections.

Prevalence of Shiga toxin-producing Escherichia coli in food products of animal origin as determined by molecular methods

“…Independently of the method employed, in this study the STEC prevalence resulted to be higher than what has been previously reported (Brooks et al, 2001;Doyle and Schoeni, 1987;Fantelli and Stephan, 2001;Pradel et al 2000;Xia et al, 2010). This could be attributed to the different experimental approaches employed for the detection but also to the different types of foodstuffs considered.…”

Virulence gene profiles of Shiga-toxin producing Escherichia coli isolates from retail raw meat in Iran.

“…Furthermore, although the contamination rate of mutton in this study (13.3%) was lower than the results reported in Iran (35.4%; and New Zealand (17%; Brooks et al, 2001), it was higher than the rate observed in previous investigation in Italy (7.1%; Franco et al, 2009). In addition, according to the results chicken feet showed higher contamination than chicken meat, whereas previous investigations represented lower rate of contamination with STEC in chicken meat and products (Xia et al, 2010;Bai et al, 2015). Isolation of STEC from chicken meat and products represented that in addition to ruminant's meat as the major source of STEC, poultry meat may be another reservoir of contamination with this pathogen (Dipineto et al, 2006).…”

The Growing Season, but Not the Farming System, Is a Food Safety Risk Determinant for Leafy Greens in the Mid-Atlantic Region of the United States

“…PCR amplification to detect the presence of Shiga toxin genes stx 1 and stx 2 was performed using published primers (43). Briefly, a 25-l PCR amplification mixture containing 1ϫ PCR buffer (Promega), 0.1 mM each dNTP (Life Technologies), 2.5 mM MgCl 2 , 0.5 M each primer (Integrated DNA Technologies, Coralville, IA), 1.25 U of GoTaq Hot Start polymerase (Promega), and 2 l of DNA template was amplified in a C1000 Touch thermal cycler (Bio-Rad).…”