Food safety
STEC lives in the guts of ruminant animals – such as goats, cows and sheep – and only causes harm when their manure finds its way onto food that is consumed by humans. Cross-contamination can also occur at the point of slaughter. Within the hundreds of variants of E. coli, STEC is a relatively new and poisonous kind that was first associated with outbreaks of foodborne illness in the 1980s. When it first emerged in 1982, the STEC serogroup 0157 was identified as the cause of foodborne illness from eating undercooked ground meat. Since then, 0157 has been found in leafy greens, unpasteurised milk, apple juice and salami. But pathogens are living organisms that are constantly changing and evolving, and now experts believe new STEC serogroups could soon be rising up to take 0157’s dominant position. The UKHSA says, “Over the last decade we have detected changes in the types of E. coli that cause gastrointestinal infections in humans and outbreaks of foodborne disease. The serogroup of E. coli that was most common ten years ago is detected less frequently, and other serogroups have emerged.”
“It’s important that we work at every stage of the food chain to maintain good hygiene protocols, identify hazards and put in food safety chain protocols to prevent illness as food businesses must ensure the food they place on the market is safe.”
Narriman Looch, Food Standards Agency
And it is the cause of the previous summer’s outbreak – STEC 0145 – that appears to be taking STEC 0157’s place. “What we’re seeing from this group of E. coli is more diversity,” explains Dr Nicola Holden, professor in food safety at Scotland’s Rural College. “STEC 0157 has been with us the longest and used to be the most common, but it has been overtaken by other types of STEC in the last few years in England and Wales. In the last couple of years, in Scotland, we’ve been at the tipping point where 0157 is no longer the most dominant.” Improvements in detection methods mean new serogroups and strains can be more accurately detected. However, scientists are investigating other factors causing the emergence of new strains. “Something is going on with the biology of the STEC group of E. coli and we don’t understand why this is occurring. We can see evidence of evolutionary change within the organisms, but we don’t understand the basis of it. It’s keeping researchers very busy,” says Holden.
76 Herd mentality
As living organisms, pathogens will respond to human behaviour and the different conditions, scenarios and situations we impose on them – such as farming practices.
Some studies have suggested that switching cattle from their natural diet of grass to grain-based animal feed makes their digestive system more acidic. This change can create an environment that favours acid- resistant strains of E. coli, including E. coli O157. In a study published in the academic journal Science – led by Francisco Diez-Gonzalez at the division of Biological Sciences at US-based Cornell University – researchers found that cattle fed a grain-based diet had significantly higher levels of acid-resistant E. coli than those fed hay. A brief period of hay feeding was found to decrease the acid-resistant count. Acid-adapted E. coli can survive the acidic conditions of the human stomach better than those from grass-fed cattle, which could increase the risk of infection when contaminated food is consumed. Meanwhile, in their study ‘Effect of Cattle Diet on Escherichia coli O157:H7 Acid Resistance’ – from the Department of Microbiology, Molecular Biology and Biochemistry at the US University of Idaho – noted that fewer cattle shed E. coli O157:H7 when switched from a feedlot ration to a forage-based diet compared with cattle continuously fed a feedlot ration. “Whatever you feed a living thing is going to influence the microbes that are already there and change the balance of some of the harmful microbes. Cattle can change some of their harmful microbes and not really get diseased. They’re happily carrying it but if you change the native microbiota that can shift the balance for some of the organisms present in the gut,” explains Holden.
“If some of the SETC bacteria are already present in the cow’s gut then the balance might be tweaked according to the microbes that occur from the feed. And if you supplement the diet with something that might affect methane production, for example, you’re changing the ecological balance within the gut.”
Outbreak
Other industry stakeholders have raised concerns about the possible link between the increasing use of antibiotics in intensive farming and instances of E. coli. After the biggest E. coli outbreak in history in 2011 – in which serogroup 0104 infected thousands of people across 12 European countries, resulting in 54 deaths – the WHO highlighted the use of antibiotics in livestock. “In deciphering the E. coli strain responsible for the outbreaks, concerns have arisen that its antibiotic resistance might derive from widespread
Ingredients Insight /
www.ingredients-insight.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94
