Obvious, right? Well, I often see people using just water to wash their hands. This does absolutely nothing to get rid of bacteria, it just kind of spreads them around your hands which is obviously lovely. Use unscented soap and try not to contaminate the plunger (use bottled soap not a bar).

The next thing people do is not to dry their hands properly. This is almost as bad as not using soap. If you get bacteria on your hands and then just splash a bit of water on them, the next thing you touch will have infected water on it. This sounds overly dramatic but if your hands are dry the ability to transfer bacteria from your hand to the next thing you touch is pretty restricted, but transmission through covering something in water is pretty effective. So not using soap then not drying your hands is actually worse than not bothering at all.

Similarly, a little drop of water is a fabulous place to live if you’re a bacterium. You can merrily loll about splitting in half every so often; if there’s anything bacteria love more than a pool of lovely water, it’s a crowd. Again, this not only also enables growth but also transmission to anything it touches.

Bacteria are pretty much like us – they need food and water and a moderate temperature which is why freezing/boiling usually kills them and once they run out of water they eventually die.

Everything needs to be dried but tea towels are immediately not clean as soon as you use them. Within reason this is not that big a deal but ideally air-drying stops you using a dirty cloth to wipe bacteria from a little droplet all over something and then picking up another thing and spreading it to that as well.

Just don’t use them more than once before you wash them.

Fridges slow down the development of bacteria. Like us they get sluggish in the cold but they don’t die. High heat (over about 63 degrees centigrade) kills them – most of them anyway. The thing is that the temperature in between; the bit that we like, they just love that. All very well – we use cold to preserve and heat to cook and kill bacteria.

The problem is with reheating. You finish your dinner and put it in the fridge. It takes a bit of time to cool and all that time it’s in the lovely-zone for bacteria. They keep multiplying but it gradually slows down. So, you already have a lot more than you had when you put it in the fridge. They bimble along, growing a bit but not too much and then you reheat it. While you reheat it, as it gets warmer again, the bacteria multiply like teenagers on a summer holiday, If it reaches 63 degrees then great – most of them will be killed again.

Each time you cool and reheat food it goes through this cycle of two periods of time where you are encouraging bacterial growth so don’t reheat anything more than once.

Anton J. Rosenbach, that's who!

You have contracted SA, salmonella, e-coli, botulism and who knows what else this week. And you’re fine because it was small doses.

The risk with SA is that you get a bigger dose because it has multiple opportunities to grow if you reheat food that contains it.

MRSA (Methicillin-Resistant Staphylococcus Aureus) is a big thing in hospitals because it kills some people and makes loads of them ill. The MR bit is that it is resistant to antibiotics and the SA bit is the bacterium. Aureus is latin for gold. Rosenbach, who identified SA in 1884 grew two strains and when they clumped on the petri dish one lot was white (alba in latin) and the other one “golden”.

The thing is it’s everywhere, MRSA isn’t a hospital-grown thing, it’s something we take in with us - in our respiratory systems, on our clothes, all over the place - when we take someone some grapes. Yay us! “Thanks for the grapes and the life-threatening infection”.

The thing about SA is that it doesn’t die at 63 degrees. It has an ingenious thing where it lolls around in a nice temperature splitting away like other bacteria and when it gets to a temperature that might kill it it can put up a kind of shield and survive. So imagine it is in your lovely fried rice from the Chinese (SA loves rice) and you put it in the fridge and reheat it. It grew during the original cooking as things warmed up, then survived in its shield when it was full cooked, then as it colled down and you ate it it was back in the comfort zone growing merrily, then it carried on growing in the fridge and then as you heated it up it grew again but when you got it to the killing-zone it just didn’t die. Which is nice for it and not nice for you.

So, don’t reheat rice unless you have treated it properly: thorough cooking followed by quick cooling and fast reheating once is fine.