It has been a while since I substantially blogged. So, I thought I'd return to one of my favourite pet/hate topics. Cucumbers.
They have been in the news recently due to the possible link between cucumbers and the European E.Coli outbreak which appeared to start in Germany. The German authorities very quickly centred on cucumbers as being the culprits. In error as it happens, but not a bad thing as far as I'm concerned. Any adverse publicity for the slimey green things the better I say!
Cucumbers. Blood pathogens. Bean sprouts. Who would have thought it?
Well, actually, much as I'd like to condemn all cucumbers to the untimely death they received when discarded and shredded recently (see pictures), in the final event they were not to blame. boo!
The E.coli outbreak in Germany during May 2011 was actually caused by the humble bean sprout. Well, technically this isn't true either. The outbreak was most lilkely caused by poor hand hygiene.
Somebody that had a virulent strain of E.coli after eating bean sprouts failed to wash their hands sufficiently and prepared food for others which then became the carrier for the spread of the outbreak. 3,000 people were affected but not all 3,000 ate the originally contaminated bean sprouts, so humans largely had themselves to blame. A common cause of mankind's problems I think?
So, onto E.coli itself. A magnificent all-conquering bacteria in many ways..
Escherichia coli is named after Theodor Escherich who first identified the bacteria in 1885.
E.coli falls in the family 'Enterobacteria', which means that they live and thrive in the lower intestine of warm-blooded animals. Human babies are born without these bacteria but tests have shown that they populate the human intestines in less than 2 days of being born, passed to the child in water and foodstuffs. When we say 'a' bacteria this is technically wrong. E.coli bacteria come in very many flavours (though I wouldn't advise you tasting any of them for obvious reasons!).
The most feared strain of E.coli is called strain 0157. This produces the Shiga toxin, released locally in the gut to damage the cells that line the intestine. 0157 has been responsible for some very large outbreaks of food poisoning all over the world in the last decade, involving hundreds of thousands of people. This is the strain at the centre of the German outbreak.
E.coli are not all bad. We have them in our guts to help with the balance of digestive enzymes and, somewhat ironically, to protect us from other pathogenic bacteria. Only some, thankfully quite rare, strains of the bacteria cause damage to humans and other warm blooded animals.
There are 5 main 'nasty types' of E.coli, all produce the runs (diarrhea) of some form or another. Some cause only mild diarrhea (with or without fever), others diarrhea with potentially lethal damage to kidneys or the urinary system. Two types are exclusive to humans only; enteroinvasive E.coli and enteroaggregative E.coli. The most common form, enterotoxigenic E.coli (ETEC) causes more than 200 million cases of diarrhea and 380,000 deaths a year, mostly in children in developing countries and travellers.
For me the most interesting points about E.coli infections relate to their genetic characteristics. E.coli bacteria per se are not bad. As above, they live in our bodies and help us. The nasty strains are bad because they have taken on parts of DNA from other bacterium. They acquire extra genes and these genes code for toxins or proteins which turn the useful E.coli bad in the same way as you should never allow a Gremlin out in the daytime.
Another genetic trait is once turned bad, the bad strains of the bacteria not only 'give birth' to more nasty bacteria (the usual route through which say a virus or other infection spreads) but they can also pass on their genetic code horizontally across an existing population of otherwise harmless bacteria (through the same process that turned them bad in the first place). This is known as bacterial conjugation or transformation. Once a few get into your system, they turn the existing population against you as well as multiply their own. Nasty!
So, a few pictures? They are quite beautiful in their own micro-biological way..
Pretty huh?
So, what of the German outbreak? After back-tracking on their cucumber story, German health officials say a woman working in a kitchen of a catering company near Frankfurt became infected with the bacterium after eating bean sprouts and then passed it on to 20 people she prepared food for. These 20 people passed it on in turn.
Cases began appearing at the start of May 2011 and the outbreak swelled to crisis level over the next three weeks causing 39 deaths and affecting almost 3,000 people. The city of Hamburg became the outbreak epicentre.
Now,
PLEASE WASH YOUR HANDS!
