Wednesday, August 28, 2013

Clostridium in whey protein turns out not to be C. botulinum

The Ministry of Primary Industry today made a statement that tests on the Clostridium species isolated from Fonterra whey protein concentrate show that it is not C. botulinum.  The organism is C. sporogenes and poses no food poisoning threat.

This will be a huge relief to Fonterra, the New Zealand government and MPI, not to mention hundreds of parents of babies being fed on infant formula.  However, the damage to the company's reputation and the Pure New Zealand brand has been massive.  Even countries that did not receive any of the affected powder and formulae have banned the import of New Zealand dairy products.

Why has it taken so long to get a definitive answer and why did the company recall the product?

Tests of products that incorporated certain batches of whey protein concentrate showed growth of sulphite reducing clostridia, though the protein concentrate itself was within specification.  Further testing of the bacterial isolates suggested that they might be C. botulinum.  Because of the severity of the illness that this microorganism can cause, the company withdrew certain batches of whey protein concentrate from the market and advised its customers accordingly.

It is quite difficult to distinguish certain closely related types of bacteria, and this is the case with C. botulinum and C. sporogenes.  The bacteria have to be isolated in pure culture, various biochemical tests must be performed, DNA must be extracted and PCR reactions carried out with specific primers.  While this sounds easy, and appears to be very rapid if the CSI-type of TV programmes are to be believed, in practice it is very tricky and time consuming.  Extracting the DNA from the bacteria without its being degraded by DNAse enzymes is apparently difficult.  There are few laboratories in the world capable of carrying out the testing reliably.  (This is not a bacterium to be trifled with.  When I worked in England for a year at the Food Research Institute in Norwich, only vaccinated people were permitted to go into the botulinum laboratory because of the risk to workers of lethal intoxication).  The 'gold standard' test for toxigenic C. botulinum capable of causing the neuroparalysis is the mouse lethality test.  This must be performed very precisely, according to an internationally recognised approved procedure and involves specially bred mice of a particular age.  The various tests have now been completed, allowing the announcement from MPI today.

Did Fonterra do the right thing in notifying its customers of the potentially hazardous product and recalling the protein concentrate?  In my opinion, they did.  Certainly, it has caused the company embarrassment and financial loss, but what of the other option - keeping quiet and hoping the problem would go away?  The death of even a single baby from botulism would have been far more damaging, and devastating for the parents.

Will things change in the future?  Only time will tell what regulatory changes may follow, and new testing requirements are imposed.  One thing is sure: occasionally, food manufacturers will make a mistake; equipment will malfunction, or a set of circumstances will come together that result in potentially unsafe food.  The entire food industry must strive to reduce the frequency of these incidents to an absolute minimum by close process control, based on appropriate and robust risk assessment and hazard control measures.

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