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The EU and US positions at a Codex meeting to set international standards on food safety foreshadow future legislation that would affect hygiene control measures in manufacturing plants, and the manufacture of powdered formulae, ready-to-eat foods, and pasteurised liquid eggs.

In the six day meeting which ended on the 4 November in New Delhi, India, national representatives to Codex’s food hygiene committee also decided to start work on drafting safety guidelines setting standards to control Campylobacter and Salmonella specie in broiler chicken meat.

At the New Delhi meeting they discussed various positions, including those relating to proposed standards for pasteurized liquid whole eggs, hygienic practice for processing powdered formulae for infants and children, pathogen control measures for Listeria monocytogenes in ready-to-eat foods & guidelines for evaluating manufacturing control measures.

Codex is a multilateral body set up to develop food safety and other standards that would apply to all member countries.

It operates under the aegis of the UN’s Food and Agriculture Organisation and the World Health Organisation.

The standards are recognised as international benchmarks by one of the multilateral agreements of the World Trade Organisation (WTO) and aim to eliminate many of what the UN calls “unjustified technical barriers” to food imports set up by some countries.

The standards also serve to harmonise food safety laws globally, aiding multinational processors in following the law no matter where they trade.

The standards on each particular topic and food type can undergo a huge revision process at various levels of Codex decision making bodies, over a number of years. Member countries must then transcribe the standards into their national laws.

The proposed standard setting what pathogen controls for Listeria monocytogenes ready-to-eat food processors must put in place is based in the main on US risk assessments, according to Codex documents.

Based on the risk assessments, a working group led by Germany concluded that a zero tolerance standard for L. monocytogenes have a proportional reduction in the rates of illness from foods contaminated with the pathogen.

A study commissioned by the food hygiene committee showed that the application of microbiological criteria at a given point of the production chain is only one of the measures that need to be applied, to bring down contamination rates.

The committee proposes to exclude from the criteria foods that are processing in such a way to ensure the killing of L. monocytogenes and for which recontamination is not possible.

The foods must also be processed and handled under systems adhering to good hygienic practice (GHP), a separate international standard.

Such foods include those given a listericidal treatment in the package and those that are produced through aseptic processing and packaging.

The group includes dehydrated products such as powdered milk, dehydrated soup mixes, herbs and spices, fresh, uncut and unprocessed vegetables and fruits, soft drinks, beer and spirits.

At the meeting the EU delegation also proposed that the standard should specifically include ready-to-eat foods for infants and those with medical conditions.

The EU supports a 100 colony forming units per gram (cfu/g) limit on the pathogen for ready-to-eat foods, if the food manufacturer is able to demonstrate the maximum would not be exceeded throughout the shelf-life.

The EU delegation also noted that setting a zero tolerance standard, where a negative reading is set at 25g = 0.04 colony forming units per gram (cfu/g) “might cause misunderstandings”.

The EU also wants clarification on foods not covered by the testing standard, pointing out that previous discussions had also discussed products for which Listeria monocytogenes is “very unlikely” to be detected.

Clarification is also needed about the proposed exclusion of foods for which there is less than ’1 log’ growth during 1.3 times the expected shelf life, the EU stated in its submission. Various definitions of ‘shelf-life’ might confuse the issue.

At the meeting the Codex committee also set its priorities for proposed standards, with those for egg products topping the list.

Other priorities in order are standards for infant and children foods; combining two codes of practice for various nuts into one; setting a single hygienic code for fruits, vegetable and products made from them; quick frozen foods, spices and aromatic plants; low-acid and acidified low-acid canned foods and aseptically processed and packaged low-acid canned foods, natural mineral waters, frog legs, catering, and street-vended foods.

The WTO’s Codex Alimentarius Commission is the body set up to harmonise food safety and other export requirements around the world.

Member countries’ representatives meet regularly to debate a common position or standard on every aspect of such requirements, from the holding temperatures in frozen meat should be kept at, to processing requirements for specific types of cheeses.

Agreements forged at Codex meetings could eventually affect the way processors operate worldwide as they become incorporated into national laws in various countries around the world.

Source

Although it is a rare occurrence, food poisoning due to Clostridium botulinum does occur. Such is the case with an Australian (Adelaide) company who manufactures pre-packed nachos product which was linked to a botulism infection in a 26 year old Melbourne man.

Clostridium botulinum is anaerobic, Gram-positive spore-forming rods, with heat resistant spore. They can be isolated from the soil and marine environment. Some strain (non-proteolytic) can grow slowly at temperatures down to 3.3°C. They usually will not produce toxins at pH lower than 4.6 and water activity (aw) values of less than 0.94. The toxin is one of the most potent toxins known and 10 – 6g is sufficient to kill an adult human. Unlike the staphylococcus aureus toxin which is heat stable, this toxin is easily destroyed by boiling for 10 minutes. Nitrate and nitrite are preservative which are effective in inhibiting the growth of Clostridium botulinum.

In March this year, the company, Mexican Express, previously recalled its 240g “Nachos to Go” products with a best before date of April 19. After further testing, it has decided to withdraw all remaining batches from sale and stop production until further notice. Interestingly, the product won the Vili’s Cakes Leadership Through Innovation in the Food Industry Award.

Consumers holding any of the items have been advised to throw them in the bin or return them.

Mexican Express managing director Ian Young said his first priority was the health and welfare of consumers. “We are putting the public first,” he said. “We are withdrawing Nachos to Go and have suspended production until the source of the botulism is found and we are satisfied about the product’s safety.”

The decision to stop production also followed intense discussions with health department officials in Adelaide and a review of the product formulation by the Dairy Authority of South Australia and Food Science Australia. I don’t think they had a choice.

Here’s what the company say about their hygiene,

“The company follows a strict step-by-step process to ensure it provides a safe, hygienic manufacturing environment for its products. Its QA operation has an SGS HACCP rating.” as for their HACCP plan, they must have forgotten one small Critical Control (CCP). So much for food companies using HACCP to ensure food safety and for SGS auditing their Quality systems.

For more information on the company profile click here.

While antibiotics eliminate disease-causing pathogens they also disrupt the protective micro flora of the intestinal tract. This micro flora normally prevents opportunistic pathogens from establishing in the intestinal tract via competitive inhibition. However, after long-term antibiotic exposure this protective barrier is disrupted, leaving the host vulnerable to subsequent infection by organisms such as Clostridium difficile. Almost all antimicrobials have been implicated in the process, however, clindamycin, second and third generation cephalosporins, and fluoroquinolones are the major antibiotics involved (Gerding, 2004). The next step leading to Clostridium difficile associated diseases (CDAD) involves exposure to toxigenic Clostridium difficile. This can be facilitated via asymptomatic carriers, hospital staff for example or symptomatic hospital patients who shed Clostridium difficile cells and spores into the hospital environment. Consequently, infected fomites also become vehicles for transmission.

Once Clostridium difficile establishes in the colon, it can produce toxin A (an enterotoxin), toxin B (a cytotoxin) or a binary toxin. Individually or in combination these toxins cause changes to the cytoskeletal organization of enterocytes, fluid secretion, leukocyte chemotaxis and the up regulation of cytokines, all subsequently leading to mucosal damage, which manifests as diarrhea or PMC.

Data from the National Nosocomial Infections Surveillance system, the Centers for Disease Control and Prevention, and the Emerging Infection Network of the Infectious Diseases Society of America, all show that the disease rates and severity of CDAD have increased over the past few years (McDonald et al., 2005). Reasons for this rise may include the emergence of hypervirulent strains, strains with a functional binary toxin gene or deletions in the tcdC gene, or those that have emerged with resistance to common antibiotic therapy. Whatever the reasons may be, it is paramount that we reassess current laboratory diagnostic techniques so that all possible strains including epidemic strains can be detected.

One of the problems with current laboratory techniques is the failure to quickly detect hypervirulent strains of toxinotype III ribotype 027 – a strain that has been reported to be present and active in Canada, the United States, the United Kingdom, and the Netherlands. This hyper-producer of toxins produces 16 to 23 times more toxins A and B than the reference strain VPI 10463 (Pépin et al., 2005); it is therefore capable of inducing very severe diarrhea. To complicate matters, hyper producing strains (those similar to that of ribotype 027) cause what is known as a prozone effect. This is a phenomenon in which mixtures of specific antigen and antibody do not agglutinate or precipitate visibly because of an excess of either antigen or antibody, and in this case, it is the antigen (Clostridium difficile toxins) that is in excess. As a result, commercial enzyme immunoassays often fail to detect these strains because false negative results are often instigated by this prozone effect.

A similar problem applies to strains with functional binary toxin genes and those with partial deletions. Studies by McDonald et al. (2005) and Loo et al. (2005) have detected epidemic strains, which contained binary toxin genes and a partial deletion in the tcdC gene. Because the tcdC protein is thought to function as a negative regulator of the production of toxins A and B, the authors have proposed that this 18- base pair deletion could lead to increased toxin production, and subsequently induce problems clinically as well as posing challenges for laboratory detection as discussed above. In addition, because many laboratories persist with kits that only detect toxins A or B (despite a decade of literature outlining issues with single antigen testing), those strains without functional toxin A or B genes will not be detected by this approach. Increasing literature reporting clinically significant binary toxin-producing isolates of Clostridium difficile will pose problems to labs not performing sophisticated molecular testing. However, it must be noted that molecular techniques are not economically viable, require technical laboratory expertise, and demand discovery of relevant primers for particular strains. Furthermore, very few laboratories have adopted PCR as routine practice to diagnose CDAD.

Laboratory diagnosis of CDAD in many institutions consists of a positive faecal toxin test. Laboratories have been moving more towards kits testing for both toxin A and B and away from a single antigen test strategy, albeit slowly.

Some laboratories are also incorporating faecal isolation of Clostridium difficile from stool specimens as a safety net approach to detect these newly described strains. Studies by Delmée et al. (2005) have shown that the direct faecal cytotoxin assay (the “gold standard” technique) missed almost as many cases as it detected, while the toxigenic culture was successful in detecting those that were missed by the former technique. Toxigenic culture involves a stool culture for Clostridium difficile followed by a toxin assay of Clostridium difficile colonies. This method, although time-consuming, is highly sensitive and vital for correct diagnosis and early recognition of possible outbreaks.

In addition to toxigenic culture, presumptive cell counts of leukocytes and erythrocytes should also be included in routine practices. Even though this is not a definitive marker of CDAD, knowledge of the leukocyte numbers in combination with positive culture isolation and toxin detection, provides a much stronger basis for correct diagnosis. In retrospect, there is an urgent need for laboratories to reassess their diagnostic techniques because globally, CDAD cases are increasing in numbers and severity, and emerging aberrant strains are appearing undetected by out-dated laboratory practices.

Well-known Clostridium difficile expert Prof. Thomas Riley from Western Australia has recently published a succinct article in the Medical Journal of Australia outlining the sentiment of this commentary. It is a good read for those laboratories performing Clostridium difficile detection to further enforce a review of Clostridium difficile detection methodology.

By Valerie Nguyen Department of Microbiology, School of Molecular and Microbial
Biosciences, University of Sydney Department of Microbiology, Concord Hospital, NSW Australia.

Unsatisfactory levels of C. perfringens generally occur as a result of temperature abuse where cooked foods are held at warm temperatures (<60 ºC, particularly room temperature) for extended periods of time or cooled (to 5 ºC or below) too slowly.

Foods associated with foodborne illness caused by C. perfringens include joints of meat (especially large and rolled joints) and meat and vegetable dishes such as stews and pies.

The detection of high levels (>1000 cfu per gram) of C. perfringens should result in an investigation of the food handling controls used by the food business. Levels of ≥10000 cfu per gram are considered as potentially hazardous as consumption of foods with this level of contamination may result in food borne illness.