Thursday, December 16, 2010

Microbial tongue twisters

Today Bill Marler published a link to a clip of Larry King making an ass of himself while introducing a segment on Escherichia coli.

http://www.youtube.com/watch?v=omaF9kA94Io&NR=1

Perhaps it's a good thing he used the abbreviation E. coli

That set me thinking.  Does the general public find the names of bacteria so difficult to pronounce that they put all thoughts of them to the back of their minds?  Or do they regard all bacteria as "germs"?

The difficulty is that there are literally thousands of different bacteria, so microbiologists have to give them names that mean something and so that they can be grouped for study.  Sometimes the genus is named after its discoverer, or in honour of a famous microbiologist.  Salmonella was named after D.E. Salmon, an American bacteriologist; Bacillus is named from the Latin noun meaning "a small rod", while Acetobacter is so named because it oxydises ethanol to acetic acid (vinegar).

When microbiology students start out, they often have difficulty in remembering, or even pronouncing, names like Vibrio parahaemolyticus and Pediococcus pentosaceus.  Small wonder that the rest of the population has problems.

In fact, in terms of food poisoning, Joe Sixpack doesn't need to know these names.  Basically, if you mistreat food by contaminating it, or by holding it at temperatures that permit growth, there is a possibility that numbers of pathogenic bacteria will increase to what is termed an "infecting dose" or that toxins will be secreted into the food.  The latter cause food poisoning when ingested.  So what is our favourite bloke going to do to keep himself and his family safe?

Easy - clean, cook, cover and chill.  This little mnemonic includes it all: Clean-handle all foods with clean hands and utensils; Cook frozen foods after proper defrosting and use a thermometer to ensure that poultry or meat patties are properly heated through.  If foods are to be reheated, ensure that the temperature reaches at least 75C right through to the centre; Cover cooked foods during cooling and place in the refrigerator within 30 minutes; Chill foods to 4C and hold at that temperature until served (remember that some bacteria grow readily at refrigerator temperatures, so even chilled food will not remain safe forever) or hold above 60C.  You can find more extensive guidelines for these important concepts on the MAF website in New Zealand, or the FDA sites in America.

In the Southern Hemisphere, we are at the start of the barbecuing season.  It's important to be really careful - never put cooked meat on the same plate as raw meat and pre-cook chicken legs etc. making sure that patties are heated right through.

I was once at a company barbecue, standing in line to collect my meal.  I heard someone behind me whisper "See what he takes, he's a microbiologist".  I didn't need to name the bacteria that might have survived on my meats, choosing only steak and thoroughly cooked burger patties.

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