For immediate release
7 April 2004

Poultry probiotics

Easter discovery for UK chicks

UK scientists have discovered a new way to combat food poisoning, by targeting it in living animals using beneficial bacteria. Probiotics provide fresh hope for destroying food poisoning bacteria in poultry before it enters the food chain.

Scientists at the Institute of Food Research (IFR) have discovered that the probiotic Lactobacillus johnsonii clears the pathogenic bacterium Clostridium perfringens from the gut of chicks. This bacterium can cause lesions in chicks as well as causing food poisoning in humans.

“Some poultry feed already contains probiotic bacteria, but an undefined mixture that gives inconsistent results. This research is exciting because we have used a single strain and shown that it can be targeted to eliminate a specific pathogen”, said Dr Arjan Narbad, Research Scientist at the Institute of Food Research (IFR).

The probiotic also reduced colonisation of the small intestine by E. coli, but did not clear it completely.

The scientists screened thousands of “commensal” bacteria from the adult chicken gut to identify strains that might competitively exclude “bad” bacteria. Lactobacillus johnsonii showed particular promise, and the IFR teamed up with the Veterinary Laboratories Agency to test its potential.

“For decades we have known that naturally-occurring bacteria in adult chickens can prevent pathogens from colonising in younger birds, whose gut flora is not yet well developed. But we have not known which bacteria are most effective”, said Dr Narbad. “We are particularly pleased to have identified a strain to combat Clostridium perfringens because it can not only cause food poisoning in humans, but can cause illness in chicks”.

Clostridium perfringens is naturally present in the chicken gut, normally without causing disease. Sometimes the bacteria produce toxins, and scientists believe these are what cause the disease necrotic enteritis. Necrotic enteritis has a number of symptoms in poultry, including poor weight gain and ulcers. In humans it causes intense abdominal cramps and diarrhoea, sometimes accompanied by vomiting.

British and European farmers are being encouraged to reduce their use of antibiotics in animal feed, and this research provides one viable alternative. Probiotic bacteria could have additional health benefits for poultry, such as stimulating the immune system and improving the rate of growth.

Notes to Editors

• Please contact Zoe Dunford for more information, images and an interview with Dr Narbad: 01603 255111 / 07768 164185 / zoe.dunford@ifr.ac.uk
• The Food Standards Agency’s current 5-year strategy identifies C. perfringens as one of the five organisms for which action is required to reduce the number of cases. See http://www.foodstandards.gov.uk/science/research/microbioSafety/b14programme/
• The mission of the Institute of Food Research (www.ifr.ac.uk) is to carry out independent basic, and strategic research on food safety, quality, nutrition and health. It is a company limited by guarantee, with charitable status, grant aided by the Biotechnology and Biological Sciences Research Council (BBSRC).
• The Veterinary Laboratories Agency (VLA) is an Executive Agency of the Department for Environment, Food and Rural Affairs (http://www.defra.gov.uk/corporate/vla/). It provides a specialist veterinary resource to the UK Government to help it fulfil its aims and objectives in veterinary public health and developing sustainable agriculture and food industries.
• This research is published in Letters in Applied Microbiology, Volume 38, Issue 3, Page 197.
• “Commensal” bacteria have also been described as “friendly”, or “good” bacteria. The Latin origin of the word commensal means “at table together” and refers to partners that coexist without detriment or benefit to one another. Live bacteria that confer a benefit to their host are called probiotics. Some bacteria, such as Campylobacter and Salmonella, are pathogenic in humans but commensal in their animal hosts.

What next?

• The next stage of research with Lactobacillus johnsonii will be to conduct a field trial of this probiotic strain. Preliminary studies have shown that it may also have a protective effect against Campylobacter jejuni in poultry.
• More generally, the scientists will investigate how competitive exclusion works, in order to improve on the process and find other competitive exclusion products. There are three current theories:

  1. Probiotics produce antimicrobials that destroy or inhibit the growth of bacteria.

  2. They force pathogenic bacteria to compete for nutrients.

  3. They occupy sites in the chick’s intestinal tract where pathogens would normally attach and grow.

• The scientists will also investigate any additional health benefits conferred to poultry by probiotics.

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