By Steve Flint, director, Food Division of the School of Food and Nutrition, Massey University
E. coli is one of the most well -known bacteria. Most people assume this is a serious food safety issue and in some cases, this is true. However, most E. coli are harmless inhabitants of the gastro intestinal tract of many animals. These bacteria are also widespread in the environment. So, as a food manufacturer, if you find E. coli in your food, should you be concerned?
The answer is ‘yes’ as some E. coli have the potential to cause serious illness, although the chance of the contamination being a pathogenic type is low. The fact is, E. coli should not be present in food. It is a bacterium that is very sensitive to food processing conditions such as heat, and is easily killed using typical cleaning and sanitising methods used in the food industry. If these bacteria are present in a food product, then there is the potential for another more serious pathogen to be present.
According to the ESR website for Public Health Surveillance, there were 187 cases of sickness reported in NZ in 2014 due to E. coli. This number is relatively low compared to cases due to Salmonella, another well -known food poisoning microorganism where there were 954 cases reported in 2014. https://surv.esr.cri.nz/PDF_surveillance/AnnualRpt/AnnualSurv/2014/2014AnnualSurvTables.pdf
E. coli food poisoning appears to be more common in other countries such as the Europe and the USA where there are reported cases of illness due to E. coli in food safety news websites such as Douglas Powell’s Barfblog.com http://barfblog.com/author/dougpowell/. In the US there are more than 250,000 cases annually of food poisoning due to E. coli.
The frequent reports of E. coli food poisoning in some countries are due to the consumption of risky foods. Undercooked beef burgers, frequently linked with E. coli food poisoning and common in the US, are not so common in NZ. Raw milk is another risky food that is not frequently consumed in NZ.
For me, the products of most concern are the salad foods such as lettuce and bean sprouts that have been frequently linked with food poisoning in Europe and the USA. The source of contamination of these products is, in many cases, thought to be due to contaminated water or manure from ruminants used to fertilize soils. Growers need to avoid the use of such fertilizers and suppliers of prepared salads need to thoroughly wash if salad vegetables in water containing sanitisers to lower the risk of food poisoning.