Campylobacter – Microbial Hazard identification
Laurie Curtis – November 2007
What is Campylobacter?
Campylobacter spp. are gram negative, non-sporeforming bacteria, some of which (C. jejuni, C. coli, C. lari and C. upsaliensis) are associated with gastroenteritis, although most cases of human campylobacteriosis are caused by C. jejuni. Campylobacter is now the leading cause of bacterial gastroenteritis in many developed countries.
Campylobacter is unique amongst food poisoning bacteria in that it is not normally able to grow in foods. This is because it has specific atmospheric requirements (microaerophilic conditions) for growth and can only grow at temperatures above ambient.
Occurrence in foods
Campylobacter is most often associated with fresh poultry meat and related products. A UK Food Standards Agency study has found that the level of poultry carcass contamination in the UK is 50%, but elsewhere studies have found contamination rates of at least 60 %, with up to 107 Campylobacter cells per carcass being recorded. Fresh poultry is more frequently and more heavily contaminated than frozen.
Campylobacter species have also been isolated from other fresh meats such as beef, lamb, pork and offal, but at lower frequencies than in poultry. Campylobacter can also be found in raw milk, shellfish, mushrooms and salads.
Hazard characterization
Effects on health
The infective dose for Campylobacter may be less than 500 cells. Symptoms associated with Campylobacter infections appear between 1 to 11 days (typically 2 – 5 days) after infection. Symptoms can vary widely and usually start with muscle pain, headache and fever. Most cases involve diarrhoea, and both blood and mucus may be present in stools. Nausea occurs, but vomiting is uncommon. Symptoms can last from 1 to 7 days (typically 5 days). The infection is usually self-limiting. Campylobacter enteritis is most commonly associated with children (less than 5 years) and young adults. Death rarely occurs, particularly in healthy individuals. However, mortality rates associated with C. jejuni in the US have been estimated at 1 per 1,000 cases.
Although complications of campylobacteriosis are rare, arthritis (e.g. Reiter’s syndrome) can occur and severe abdominal pain can be confused with appendicitis. Reactive arthritis occurs in 1 % of cases and 0.1 % can suffer Guillain-Barré syndrome (a severe nerve disorder, which can lead to paralysis). Around 15 % of those affected recover from Guillain-Barré syndrome, 3 – 8 % die and the remainder suffer from some degree of disability. Bacteraemia can also occur, particularly in the elderly.
Incidence and outbreaks
Campylobacter has recently been recognized as the principal cause of bacterial gastroenteritis in Europe and nearly 200,000 cases were reported in the EU in 2005. The majority of these are thought to be foodborne. A similar situation exists in North America and other countries. In 2004, New Zealand was reported to have the highest incidence of Campylobacter infection in the developed world.
Most cases of Campylobacter enteritis are sporadic, so definitive sources of infection are difficult to establish. However, most cases are thought to be associated with undercooked, or recontaminated, poultry meat. Documented outbreaks are relatively rare, but have been linked to raw and inadequately pasteurized milk, raw clams, garlic butter, fruits and contaminated water supplies. In one recorded incident in 2005, at least 80 people at offices in Copenhagen were made ill by contaminated chicken salad in canteen meals.
Sources
Campylobacters are found in the intestinal tract of many warm-blooded animals, such as cattle, sheep, pigs, goats, dogs and cats, although they are especially common in birds, including poultry. Wild birds are thought to be a reservoir for domestic and food animals.
If hygiene is poor, infected humans can transfer Campylobacter to food via the faecal/oral route and asymptomatic carriers have also been reported. Excreta from infected animals can contaminate water and mud, and Campylobacter can survive for some time in these environments, particularly when temperatures are low.
Growth and survival in foods
As previously stated, Campylobacter is unable to grow at temperatures normally used to store food. The temperature range for growth is 30 – 45 °C, with an optimum of 42 °C. Although survival at room temperature is poor, Campylobacter can survive for a short time at refrigeration temperatures – up to 15 times longer at 2 °C than at 20 °C. The organism dies out slowly at freezing temperatures.
The optimum pH for growth is 6.5 – 7.5, and the organism does not grow below pH 4.9. Survival at acid pH values is temperature dependant, but inactivation is rapid at pH values less than 4.0, especially above refrigeration temperatures.
The minimum water activity for growth is > or = 0.987 (2 % sodium chloride). The organism is sensitive to salt and, depending on temperature, levels of 1 % or more can be bactericidal (less effect being observed with decreasing temperature). Although Campylobacter is sensitive to desiccation, there are reports of survival for some time on wooden cutting boards.
Campylobacter is microaerophilic, requiring reduced levels of oxygen (5 – 6 %) to grow. The cells usually die out quickly in air but survive well in modified or vacuum packaging.
Thermal resistance
Campylobacter is heat sensitive and the cells are destroyed at temperatures above 48 °C. They do not therefore survive normal pasteurization processes applied to milk. Heat processes targeted at other poultry pathogens (e.g. Salmonella) will easily inactivate Campylobacter.
Control options
Processing
Poultry and poultry products are considered to be the main source of Campylobacter food poisoning and controls focus on measures to minimize the level of contamination during primary production and processing of poultry meat.
In many European countries measures are in place to encourage effective biosecurity and hygiene strategies to prevent the introduction of Campylobacter to flocks and reduce the incidence of infection. For example, in Denmark, ‘Campylobacter-free’ chicken meat can be marketed at a premium price, providing that it comes from flocks that meet required monitoring standards.
Much attention has also been given to measures designed to reduce high rates of cross contamination during the processing of poultry, particularly chicken, by improving the hygienic design and operation of equipment such as defeathering machines and immersion chiller tanks.
Product use
As previously discussed, Campylobacter is unable to grow in foods stored at normal temperatures. However, the potentially low infective dose means that undercooking of raw foods and/or cross contamination from raw to ready-to eat foods is a major risk factor for human campylobacteriosis.
Clear and effective cooking instructions can help to ensure that the pathogen is destroyed during the cooking stage. Undercooking and/or cross contamination at barbeques are thought to be linked to an increase in reported Campylobacter infections during summer months.
Consumer education and domestic hygiene training can help prevent the transfer of Campylobacter from raw to ready-to-eat foods. Consumers should be advised not to wash meat and poultry carcasses prior to cooking to help prevent water splashes and aerosols from contaminating kitchen surfaces. Any surfaces that could be potentially contaminated, such as in meat preparation areas, as well as chopping boards, should be thoroughly disinfected after use.
Legislation
No specific requirement is made under European Commission legislation with regard to levels of Campylobacter species in food. Requirements for their control are covered under EU general food safety requirements.
The UK Health Protection Agency (HPA) has published guidelines on acceptable levels of microorganisms in various ready-to eat foods (see link below). These state that ready-to-eat foods should be free from Campylobacter spp. and that, even in small numbers, their presence in processed, ready to eat foods, “results in such foods being of unacceptable quality/potentially hazardous.”
Sources of Further Information
Published
Nachamkin I.
Campylobacter jejuni,
In Food Microbiology: Fundamentals and Frontiers. 2nd Edn. Eds. Doyle, M.P., Beuchat, L.R and Monteville, T.J., Washington D.C. ASM press. 2001. 179 -192.
International Commission on Microbiological Specifications for Foods
Campylobacter
In Microorganisms in foods, volume 5: microbiological specifications of food pathogens. Edited by International Commission on Microbiological Specifications for Foods. London. Blackie. 1996, 45 — 65.
On the web
Risk profile: Campylobacter jejuni /coli in mammalian and poultry offals. Institute of Environmental Science and Research Limited. (January 2007).
http://www.nzfsa.govt.nz/science/risk-profiles/FW0465_Campy_in_Offal_PVDL_final_comments_Mar_2007.pdf
Risk profile: Campylobacter jejuni/coli in red meat. Institute of Environmental Science and Research Limited. (January 2007).
http://www.nzfsa.govt.nz/science/risk-profiles/FW0485_Campy_in_red_meat_Final_sent_to_NZFSA_Jan_07.pdf
Advisory Committee on the Microbiological Safety of Food. Second Report on Campylobacter. (2005)
http://www.food.gov.uk/multimedia/pdfs/acmsfcampylobacter.pdf
Risk Profile: Campylobacter jejuni/coli in poultry (whole and pieces). Institute of Environmental Science and Research Limited. (June 2003).
http://www.nzfsa.govt.nz/science/risk-profiles/campylobacter.pdf
Risk assessment of Campylobacter spp. in broiler chickens and Vibrio spp. in seafood. World Health Organization. (2002)
http://www.who.int/foodsafety/publications/micro/aug2002.pdf
Control of Campylobacterspecies in the food chain. Food Safety Authority Ireland. (2002)
http://www.fsai.ie/publications/reports/campylobacter_report.pdf
Guidelines for the microbiological quality of some ready-to-eat foods sampled at the point of sale. Health Protection Agency. (September 2000)
http://www.hpa.org.uk/cdph/issues/CDPHvol3/No3/guides_micro.pdf
Fonte: http://www.foodsafetywatch.com/
