Isolation of Escherichia coli O157:H7 from retail fresh meats and poultry

Abstract

A total of 896 samples of retail fresh meats and poultry was assayed for Escherichia coli serogroup 0157:H7 by a hydrophobic grid membrane filter-immunoblot procedure developed specifically to isolate the organism from foods. The procedure involves several steps, including selective enrichment, filtration of enrichment culture through hydrophobic grid membrane filters, incubation of each filter on nitrocellulose paper on selective agar, preparation of an immunoblot (by using antiserum to E. coli 0157:H7 culture filtrate) of each nitrocellulose paper, selection from the filters of colonies which corresponded to immunopositive sites on blots, screening of isolates by a Biken test for precipitin lines from metabolites and antiserum to E. coli 0157:H7 culture filtrate, and confirmation of isolates as Vero cell cytotoxic E. coli 0157:H7 by biochemical, serological, and Vero cell cytotoxicity tests. E. coli 0157:H7 was isolated from 6 (3.7%) of 164 beef, 4 (1.5%) of 264 pork, 4 (1.5%) of 263 poultry, and 4 (2.0%) of 205 lamb samples. One of 14 pork samples and 5 of 17 beef samples contaminated with the organism were from Calgary, Alberta, Canada, grocery stores, whereas all other contaminated samples were from Madison, Wis., retail outlets. This is the first report of the isolation of E. coli 0157:H7 from food other than ground beef, and results indicate that the organism is not a rare contaminant of fresh meats and poultry.

The optimization of isolation media used in immunomagnetic separation methods for the detection of Escherichia coli O157 in foods

“…It is probable that ce®xime and cefsulodin at this reduced level are below the concentrations that have an effect on target recovery. Doyle and Schoeni (1987) proposed the use of modi®ed TSB + N at 37°C, which in our study compared favourably with other media tested, although incubation at 42°C improved recovery. However, it proved slightly inferior to BPW-V pH 7á0 and BPW-V + C + C. Szabo et al (1990) tested TSB at 35 and 43°C, and found the addition of bile salts and novobiocin at the higher temperature improved recovery of E. coli O157 in foods containing competing micro-organisms.…”

Serotypes and antibiotic resistance of Verotoxigenic (VTEC) and Necrotizing (NTEC) Escherichia coli strains isolated from calves with diarrhoea

“…0153 and 0157) have been also previously reported in VTEC strains isolated from calves [6,14]. VTEC strains of serotype 0157:H7, in addition to their relevance as the most important pathogen causing human haemolytic uraemic syndrome [4,5,12,23] were also isolated from fresh meats, poultry and unpasteurized milk [15,16]. Furthermore, in one of these studies [16] it was possible to establish the epidemiological relation between the consumption of unpasteurized milk contaminated by a VTEC strain of serotype 0157:H7 and the consequent development of diarrhoea and haemolytic uraemic syndrome in children.…”

“…Bovine VTEC strains belonging to at least 13 different O-groups, including some of those reported in human VTEC such as 04, 05, 026, 055, 0111, 0153 and 0157, have been found [4,6,13]. VTEC strains of serotype 0157:H7 were isolated from calves with diarrhoea [14], from fresh meats [15] and from unpasteurized milk [16]. Consequently, the present knowledge on VTEC strains supports a role of cattle as a reservoir of E. coli strains pathogenic for humans.…”

Avian Colibacillosis and Salmonellosis: A Closer Look at Epidemiology, Pathogenesis, Diagnosis, Control and Public Health Concerns

“…Chapman et al [199] reported that at that time no bacteriologically confirmed human cases of O157 infections had been observed, caused by poultry. Nonetheless, chicken meat was sometimes positive for VTEC [201,202]. In addition, Manges et al [203] conducted a case-control study between April 2003 and June 2004 and they demonstrated that antimicrobial resistant, urinary tract infection (UTI) causing E. coli could have a food reservoir, possibly in poultry or pork.…”