Sani - When you look at the issue of contamination in hospitals and transferral of organism particularly in relation to C. difficile we know that most of the contamination comes from patients that are already infected with the infection, with the disease, with the organism.  The crucial thing really is to make sure that you clean the surfaces.  You clean the sites where you touch quite frequently by healthcare workers.  You also isolate the patient who’s symptomatic.  It’s less of an issue in terms of people bringing it in.  You’re not going to bring it in from the community on your footwear, for instance.

Sani - Ordinary soap will help because you are trying to reduce the burden of infection on your hands.  Ordinary soap will help in terms of C. difficile.  We know even when you finish washing your hands this is talking outside of the C. difficile spectrum (in terms of MRSA infection, for instance) if you use that hand gel - if you haven’t really washed your hand and you have a lot of debris that alcohol hand gel is not going to work.  Yes, using soap and water is definitely a good thing.

Chris - There’s a physical detachment of organisms by placing your hands with friction under running water.  We know that helps to knock them off.

Chris - That’s a morphine-based drug.  The basis of that I presume is it treated the symptoms rather than the cause so it probably would make C. diff worse, wouldn’t it?

Sani - Absolutely.  With C. difficile you really want the toxin and the bacteria out of your system.  You don’t really want to give a drug to help the toxin stay in and cause more damage.

Chris - That toxin, how does it work?  Why is it bad for your guts?

Sani - The toxin works by inducing quite an intense inflammation.  Clostridium difficile produces two types of toxins: toxin A and toxin B.  These latch on to receptors and simulate production of inflammatory mediators called cytokines and this causes quite an intense inflammation with cell death and subsequent necrosis and breakdown of the normal barrier that you find in the large bowel.

Chris - That presumably means you’ll not only lose fluid from the body but you may also an access point for other nasty bacteria to get in as well.

Sani - Yes, and you might actually perforate your bowel.

Joanna - If you don’t mind I’ll have to go back a little bit and talk about bugs on surfaces generally.  Bacteria generally on the planet live attached onto surfaces.  Most of them are attached onto surfaces so it’s where they would rather be. If you had bacteria in your mouth, if you swallow them they die but if they stick to your teeth it’s much better for them.  It’s the best place for them to be attached to a surface. They’ll stick to lots of different surfaces.

In the food industry and where we’ve been talking about surfaces in hospitals you’re just looking at survival of organisms that have stuck onto the surfaces.  Perhaps they’ve been put there by people touching them or with the chopping board they’ve come into contact with a surface through the meat or whatever it is that’s been chopped.  That’s a sort of contact and survival.  The organisms haven’t attached.  They’ve just been put there and then they’re surviving.  We call that attachment at a solid air interface.

If you allow the organisms to grow in a surface that’s got liquid in it at a solid liquid interface we call that a biofilm.  Again, although organisms are very happy to do that they’ll stick onto a surface and then grow.  In a roundabout way they’ll stick on to anything really and it’s trying to reduce their ability to stick.

The other thing with biofilms – if you think about catheters or contact lenses or dentures – any sort of plastic that you might implant in the body.  The first thing that will stick to those materials is organic molecules from the liquid around them.  It might be saliva or tear fluid or urinary proteins.  Then the bacteria will stick to those.  The biofilm will form on top of that conditioned surface too.

Sani - Really bacteria are quite clever as we all know.  The issue is provided we keep on developing new antibiotics we’ll be a step ahead of the organism.  I don’t believe we should just stay back and say, ‘They’re probably winning anyway. Let’s leave them.’

Chris - The numbers of MRSA are going down, aren’t they?

Sani - Yes.  It’s partly because of intervention measures that have come in over the last few years.  We’re putting less intravascular devices in nowadays where we’re taking much more care when putting in plastic devices.  At the first sign of any infection these plastic devices are taken out.  It’s probably the main reason why catheter-related blood stream infections, particularly MRSA, have gone down.