Health: Mapping the DNA of superbugs on wards

Professor Mark Wilcox, next to a machine that replicates the human gut at the Department of Microbiology in The Old Medical School at Leeds General Infirmary.
Professor Mark Wilcox, next to a machine that replicates the human gut at the Department of Microbiology in The Old Medical School at Leeds General Infirmary.
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Work in Leeds is leading the way in researching c.difficile infections. Katie Baldwin visited their lab.

It’s the smell that hits you first. Though considering this is a machine which replicates the inner workings of the human gut, it’s no surprise that the aroma surrounding it isn’t exactly sweet.

But this collection of tubes and beakers is playing a crucial role in the treatment of a so-called superbug.

As are the unidentified volunteers who generously donate the substance which is causing the somewhat unpleasant smell.

This working model of the gut is located in the Department of Microbiology at Leeds Teaching Hospitals NHS Trust.

In the grand surroundings of the Old Medical School at Leeds General Infirmary, a team of experts are at the forefront of tackling healthcare associated infections.

The most well-known of these are MRSA and C.difficle, with much of the team’s work focusing on C.diff.

“What makes C.diff tick is what we are about,” says Prof Mark Wilcox, from the Leeds Healthcare Associated Infections Research Group.

The C.diff bacteria live in the gut of many people without causing harm – about three in 100 healthy adults aged under 65 will be carrying it.

Around 60 or 70 people will have antibodies towards the bacteria though, suggesting they have been exposed to it.

However if C.diff bacteria multiply, often because other ‘good’ bacteria have been killed by antibodies given to a patient who is ill, such as in hospital, it can cause harm.

In recent years, there has been much focus in the health service on C.diff as among vulnerable people, it can lead to severe illness or even death.

Those especially at risk are older people, amongst whom the infection is more common – around 10 to 15 people over 65 in 100 will be carrying it.

So the working model of the gut aims to help replicate the bodies of older people in particular, to assist with the development of new treatments.

“It mimics the large intestine and we can simulate C.diff infection,” Prof Wilcox said.

“We can put a drug in to see how good it is at treating the infection.

“We can see with a high degree of accuracy whether a drug is going to work or not.”

That means not only can tests be done without affecting patients, but also combinations of drugs can be tried to see how they perform.

It’s one of the ways that the team are developing new treatments.

Their current work includes developing an antibody which acts against the toxins produced by C.diff, with the help of a firm who have previously developed an anti-snake venom.

There are also investigations of a new antibiotic for C.diff with a clinical trial set to start in Leeds next year, and another to test whether a certain antibiotic prevents the bug spreading.

As well as looking at treatments for the infection, the team have been developing improved diagnosis of the bug.

“Most people think that when you’re trying to diagnose an infection, it’s a straightforward thing,” Prof Wilcox said.

“The problem with C.diff is that you can have the bug but not the infection.”

A major study of 10,000 patients, led in Leeds, enabled the experts to find the best methods of diagnosis.

“We rewrote the NHS guidance for the diagnosis of C.diff,” says Prof Wilcox.

Identifying the strain of C.diff involved in an infection is crucial, and the team run a network of eight laboratories across England and Northern Ireland.

Together these test 6,000 infections a year, more than one in three cases diagnosed.

Identifying the strain of C.diff is very important. By finding out, hospital trusts can discover whether the variety is especially harmful, or has worse outcomes for patients than other types.

And they use CSI-style DNA testing technology to do it.

“If you’ve got clusters of cases, are they an outbreak or not? You can look at their DNA to see,” Prof Wilcox added.

“That’s the next place that microbiology is going. We haven’t developed it but been at the forefront of using it to type C.diff.

“That’s really exciting because we’re at the forefront of the world.”

GET THE LOWDOWN

Healthcare-acquired infections have fallen dramatically recently.

Over the past five years, C.difficile infections within Leeds hospitals have fallen by 79 per cent while MRSA bloodstream infections are down by 92 per cent.

That reflects a national trend which has coincided with the development of the network of testing labs led from Leeds.

“I’m not sure that’s solely responsible for the decrease but it’s been an important tool to use,” Prof Wilcox said.

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