Category Archives: STX 2

Research – Prevalence and Characterization of Shiga Toxin Producing Escherichia coli Isolated from Animal Feed in Croatia

MDPI

A survey on prevalence and number of Shiga toxin-producing Escherichia (E.) coli (STEC) in animal feed was carried out over a period of nine years in the Republic of Croatia. A total of 1688 feed samples were collected from feed factories and poultry farms. Analysis included two standard procedures: sample enrichment and (a) immunomagnetic separation and plating on two selective media; or (b) plating on two selective media. Confirmation of STEC included morphological examination, biochemical tests, serotyping, and polymerase chain reaction. Morphological and biochemical characterization revealed 629 E. coli strains. Further serological screening method revealed 78 STEC and EPEC serotypes, while only 27 strains were confirmed as STEC with PCR. All positive samples (1.6%) originated from poultry farms and contained combination of virulence genes: eaeA, stx1, and/or stx2. Since the presence of stx (especially stx2) and eae are identified as risk factors for development of severe diseases in humans, results of this survey indicate that avian sources of STEC infections might be one of those “undefined sources” of human illnesses. Further research is necessary for evaluation of risks posed by contaminated feed, poultry, and environment.

USA – What you need to know about E. coli O157:H7 and its complications during an Outbreak

Food Poison Journal

E. coli O157:H7 is one of thousands of serotypes of Escherichia coli.

E. coli O157:H7 was first recognized as a pathogen in 1982 during an investigation into an outbreak of haemorrhagic colitis associated with consumption of hamburgers from a fast-food chain restaurant. Retrospective examination of more than three thousand E. coli cultures obtained between 1973 and 1982 found only one isolate with serotype O157:H7, and that was a case in 1975. In the ten years that followed, there were approximately thirty outbreaks recorded in the United States. This number is likely misleading, however, because E. coli O157:H7 infections did not become a reportable disease in any state until 1987, when Washington became the first state to mandate its reporting to public health authorities. Consequently, an outbreak would not be detected if it was not large enough to prompt investigation.

E. coli O157:H7’s ability to induce injury in humans is a result of its ability to produce numerous virulence factors, most notably Shiga toxin (Stx), which is one of the most potent toxins known to man. Shiga toxin has multiple variants (e.g., Stx1, Stx2, Stx2c), and acts like the plant toxin ricin by inhibiting protein synthesis in endothelial and other cells. Endothelial cells line the interior surface of blood vessels and are known to be extremely sensitive to E. coli O157:H7, which is cytotoxigenic to these cells.

RASFF Alerts – STEC E.coli – Minced Meat – Chilled Meat

RASFF

STEC (stx+;eae+) in minced meat from Belgium in Germany, Netherlands and UK

RASFF

COLI STEC IN CARNE REFRIGERATA DALL’ARGENTINA in Italy

Research – A bacteriological survey of fresh minced beef on sale at retail outlets in Scotland in 2019: three food-borne pathogens, hygiene process indicators and phenotypic antimicrobial resistance.

Journal of Food Protection

The health and economic burden of foodborne illness is high, with approximately 2.4 million cases occurring annually in the United Kingdom. A survey to understand the baseline microbial quality and prevalence of food-related hazards of fresh beef mince on retail sale could inform risk assessment, management and communication to ensure the safety of this commodity. In such a survey, a two-stage sampling design was used to reflect variations in population density and the market share of five categories of retail outlets in Scotland.  From January to December 2019, 1009 fresh minced beef samples were collected from 15 Geographic Areas. The microbial quality of each sample was assessed using Aerobic Colony Count (ACC) and generic E. coli count. Samples were cultured for Campylobacter and Salmonella and PCR was used to detect target genes (stx1 all variants, stx2 a-g, and rfbO157) for Shiga toxin-producing Escherichia coli (STEC). The presence of viable E. coli O157 and STEC in samples with a positive PCR signal was confirmed via culture and isolation. Phenotypic antimicrobial sensitivity patterns of cultured pathogens and 100 generic E. coli isolates were determined, mostly via disc diffusion. The median ACC and generic E. coli counts were 6.4 x 105 (Inter-quartile range (IQR):6.9 x 104 to 9.6 x 106) and <10 cfu per gram (IQR:<10 to 10) of minced beef respectively. The prevalence was 0.1% (95% confidence interval C.I. 0 to 0.7%) for Campylobacter, 0.3% (95% C.I. 0 to 1%) for Salmonella, 22% (95% C.I. 20% to 25%) for PCR positive STEC and 4% (95% C.I. 2 to 5%) for culture positive STEC. The evidence for phenotypic antimicrobial resistance (AMR) detected did not give cause for concern, mainly occurring in a few generic E. coli isolates as single non-susceptibilities to first-line active substances. The low prevalence of pathogens and phenotypic AMR is encouraging but ongoing consumer food-safety education is necessary to mitigate the residual public health risk.

RASFF Alert – STEC E.coli – Bovine Carcass

RASFF

STEC (stx+;eae+) in bovine carcass from Belgium in France

RASFF Alert – STEC E.coli – Cow Carcass

RASFF

STEC (stx+;eae+) in cow carcass from Belgium in France and the Netherlands

Research – Assessment of the Microbiological Quality and Safety of Unpasteurized Milk Cheese for Sale in England between 2019 and 2020

Journal of Food Protection

Cheese made with unpasteurized milk has been associated with outbreaks of illness. However, there are limited data on the prevalence of Shiga toxin–producing Escherichia coli (STEC) in these products and a lack of clarity over the significance of E. coli as a general indicator of hygiene in raw milk cheeses. The aim of this study was to provide further data to address both of these issues, as well as assessing the overall microbiological quality of raw milk cheeses available to consumers in England. A total of 629 samples of cheese were collected from retailers, catering premises, and manufacturers throughout England. The majority (80%) were made using cow’s milk, with 14% made from sheep’s milk and 5% from goat’s milk. Samples were from 18 different countries of origin, with the majority originating from either the United Kingdom (40%) or France (35%). When interpreted against European Union microbiological criteria and United Kingdom guidance, 82% were considered to be of satisfactory microbiological quality, 5% were borderline, and 12% were unsatisfactory. Four samples (0.6%) were potentially injurious to health due to the isolation of STEC from one, >104 CFU/g of coagulase-positive staphylococci in two, and >100 CFU/g of Listeria monocytogenes in the fourth sample. Indicator E. coli and Listeria species were detected more frequently in soft compared with hard cheese. Higher levels of indicator E. coli were significantly associated with a greater likelihood of detecting Shiga toxin genes (stx1 and/or stx2).

Research – Wild Boars as Reservoir of Highly Virulent Clone of Hybrid Shiga Toxigenic and Enterotoxigenic Escherichia coli Responsible for Edema Disease, France

CDC

Edema disease is an often fatal enterotoxemia caused by specific strains of Shiga toxin–producing Escherichia coli (STEC) that affect primarily healthy, rapidly growing nursery pigs. Recently, outbreaks of edema disease have also emerged in France in wild boars. Analysis of STEC strains isolated from wild boars during 2013–2019 showed that they belonged to the serotype O139:H1 and were positive for both Stx2e and F18 fimbriae. However, in contrast to classical STEC O139:H1 strains circulating in pigs, they also possessed enterotoxin genes sta1 and stb, typical of enterotoxigenic E. coli. In addition, the strains contained a unique accessory genome composition and did not harbor antimicrobial-resistance genes, in contrast to domestic pig isolates. These data thus reveal that the emergence of edema disease in wild boars was caused by atypical hybrid of STEC and enterotoxigenic E. coli O139:H1, which so far has been restricted to the wildlife environment.

Research – Occurrence of the seven most common serotypes of Shiga toxin-producing Escherichia coli in beef cuts produced in meat-processing plants in the state of São Paulo, Brazil

JFP

Healthy cattle are considered the main reservoir of Shiga toxin-producing Escherichia coli (STEC) strains, so in some places in the world, products derived from beef are the most common source for disease outbreaks caused by these bacteria. Therefore, in order to guarantee that the beef produced by our slaughterhouses is safe, there is a need for continuous monitoring of these bacteria. In this study, 215 beef cuts were evaluated, including chilled vacuum-packed striploins (151 samples), rib eyes (30 samples), and knuckles (34 samples), from March to June, 2018. These meat samples were collected from the slaughter of unconfined cattle, being arbitrarily collected from eight meat-processing companies in São Paulo state, Brazil. Each sample was examined for the presence of STEC toxin type ( stx 1 and/or stx 2 genes) and also the E. coli attaching-and-effacing ( eae ) gene, which were determined by a multiplex PCR assay. Here we show that the major seven STEC strains (O serogroups O26, O45, O103, O111, O121, O145, and O157) are not detected in any of the analyzed beef cut samples; however, three of them presented the virulence eae gene. Therefore, the absence of STEC strains in the beef samples may be an indication of the low prevalence of this pathogen in the cattle herd on the farm, associated with good hygiene and handling practices adopted by the meat industry.

Research – An assessment of the microbiological quality and safety of unpasteurised milk cheese for sale in England during 2019 – 2020

Journal of Food Protection

Cheese made with unpasteurised milk has been associated with outbreaks of illness. However, there are limited data on the prevalence of shiga-toxin producing E. coli (STEC) in these products, and a lack of clarity over the significance of E. coli as general indicators of hygiene in raw milk cheeses. The aim of this study was to provide further data to address both of these issues as well as assessing the overall microbiological quality of raw milk cheeses available to consumers in England. A total of 629 samples of cheese were collected from retailers, catering premises and manufacturers throughout England. The majority (80%) were made using cow’s milk with 14% made from sheep’s milk and 5% from goat’s milk. Samples were from 18 different countries of origin, with the majority originating from either the UK (40%) or France (35%). When interpreted against EU microbiological criteria and UK guidance, 82% were considered to be of satisfactory microbiological quality, 5% were borderline and 12% were unsatisfactory. Four samples (0.6%) were potentially injurious to health due to the isolation of STEC from one, >10 4 cfu/g of coagulase positive staphylococci in two and >100 cfu/g of Listeria monocytogenes in the fourth sample. Indicator E. coli and Listeria species were detected more frequently in soft compared to hard cheese. Higher levels of indicator E. coli were significantly associated with a greater likelihood of detecting shiga toxin genes ( stx 1 and/or stx 2).