Genome sequencing halts superbug outbreak

By Kate Kelland
Reuters
Researchers have used DNA sequencing for the first time to identify, analyze and put a halt to an infectious disease outbreak in a hospital.

The success of the technique, which used fast genome sequencing technology to control an outbreak of the MRSA superbug on a baby ward, suggests it could be used to control hospital bugs, salmonella and E.coli infections and diseases like tuberculosis, scientists said.

"What we have glimpsed through this pioneering study is a future in which new sequencing methods will help us to identify, manage and stop hospital outbreaks," said Nick Brown, an infection control doctor at Addenbrooke's Hospital Cambridge, who co-led the study and presented the findings at a briefing.

MRSA, or methicillin-resistant staphylococcus aureus, is a drug-resistant bacterial infection, or superbug, and a serious public health problem. When outbreaks occur in hospitals it can lead to the closure of whole wards with many people infected.

The bug kills an estimated 19,000 people in the United States per year. Although rates of MRSA infection have come down significantly in Britain in recent years, it still presents a major threat with several hundred deaths a year and high hospital costs involved in managing infected patients.

Julian Parkhill from Britain's Sanger Institute, who also worked on the study, said there is a "real health and cost burden from hospital outbreaks" which could be significantly reduced or eliminated if they were contained swiftly.

In the study, staff at Addenbrooke's hospital using routine screening over a six month period found 12 patients carrying MRSA. Because they were only using standard tests, which provide limited information, the infection control team was not able to tell if the 12 were part of an outbreak, or were unconnected cases that did not present a threat.

MRSA is a bug present in around one percent of the population at any time, and does not always cause infection.

Parkhill and Brown's team analyzed MRSA samples from the 12 patients with DNA sequencing technology and found that all the MRSA bacteria were closely related, confirming an outbreak.

By tracing relatives and other people who had recent links to the hospital, they also found the outbreak was more extensive than previously thought, with twice as many people carrying or infected with the MRSA strain.

While this sequencing study was underway, the hospital's infection control team found a MRSA case in the special care baby unit - 64 days after the last MRSA patient had left.

The team used advanced DNA sequencing to show in real time that this strain was also part of the same outbreak, raising the possibility that a staff member was unknowingly carrying and transmitting the MRSA strain.

After screening 154 staff they found one carrying MRSA and, using DNA sequencing, confirmed it was the strain linked to the outbreak. The worker was quickly treated to eradicate the bug, and any further spread was stopped.

The researchers, whose findings were published in the Lancet Infectious Diseases journal, say this kind of fast genome sequencing could eventually form the basis for regional or national infection surveillance program designed to nip infectious disease outbreaks in the bud.

"This technology holds great promise for the quick and accurate identification of bacterial transmissions in our hospitals and could lead to a paradigm shift in how we manage infection control and practice," said Parkhill. 

It could also be used for outbreaks of food-borne infections like salmonella or E.coli. Genome sequencing was used in an E.coli outbreak in Europe in 2011, but only in the latter stages to help identify the source.

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Discuss this post

This is awesome! This is the first time i have heard of genome sequencing actually being used in a practical fashion. I wonder if its possible to use this to create drugs that neither bacteria or viruses can resist.

  • 2 votes
Reply#1 - Tue Nov 13, 2012 11:50 PM EST

Probably not any more of a chance than we currently have. The information has been here, hospitals are just learning to use it.

I'd say alcohol is the only think I know that viruses/bacteria aren't known to be resistant to.

    #1.1 - Wed Nov 14, 2012 1:48 AM EST

    Alcohol is only partly effective against most non-enveloped viruses (like Hepatitis A), and isn't affective against spore forming bacteria like clostridium difficile(causes diarrhea) or fungal spores. Since the alcohol can't enter the spore to kill the bacteria.

    It is incredible none the less for scientists to be able to use what knowledge they have gleaned from recent research to be able to stop the spread of a disease, that has the potential to kill.It really shows the immediate benefits, not sometime, but now, for what benefits can be found from so much funding that has been poured into trying to help man understand the wonder of his often taken for granted masterpiece, the human body.

      #1.2 - Wed Nov 14, 2012 5:08 AM EST
      Reply

      How many more staff at other hospitals unknowingly carry and spread MRSA to their patients?

        Reply#2 - Wed Nov 14, 2012 2:58 AM EST

        This from the Center for Disease Control: 443,000 deaths annually (including deaths from secondhand smoke), yet no genome sequencing is being done to help people to stop smoking. Our federal government is STILL SUBSIDIZING TOBACCO GROWERS! Alcohol accounts for 75,000 deaths per yer, and the fact sheets are hidden deep within the CDC records. The federal government continues to subsidize Caribbean rum distilleries, and makes approximately $4.6 billion on alcohol taxes, but no genome sequencing has been done to help people shake alcoholism. According the to Center for Disease Control NOT ONE FATALITY has EVER been attributed to marijuana use. An average male would need to smoke 8000 joints in ten minutes to even approach toxic THC levels. Why not concentrate on some IMPORTANT problems here? Legalize pot and stop subsidizing industries that account for one in four deaths in America every year!

        • 1 vote
        Reply#3 - Wed Nov 14, 2012 1:25 PM EST

        Apparently you didn't read the article. The genome sequencing traced the route of infection, not what caused it.

        However, if you applied the article to your statements, you would discover that marijuana has caused many deaths--suppliers killing one another, robberies to support habits, users and suppliers warring over it. Recently, a young man from our county was beat to death over a bag of marijuana. Using this sequencing as in the article, the marijuana from the bag could be traced back to the original supplier, who, upon arrest could then spill his guts to whom he sold the dope to. Further analysis would pass it down the line as to the users and suppliers, eventually ending up with the boy who was killed, and his supplier. ~~ or something like that. It has nothing to do with human genome of the user, it has to do with the problem itself, and how it is traced.

        (Come to think of it, I should send this to my sheriff. It might cut down on the illegal drugs in our community. Thanks for making me think it through.)

        When I worked at the local rehab center, the number of in-patients who started on marijuana was 100%. All had moved to harder substances. Some were from gangs that killed and mutilated others over drugs--including marijuana. So your argument fails when you say marijuana doesn't kill anyone, it leads to as many deaths as all the other vices, it just goes an indirect route.

        You might find the article interesting if you give it a read. Best wishes.

        • 1 vote
        #3.1 - Thu Nov 15, 2012 6:23 AM EST
        Reply

        This study (finally, a study that actually has a benefit) traces the routes of infection. This is what I get from the article: The sequencing doesn't cure the infection, but it does lead the researchers to find the "Typhoid Mary." Once "Mary" is removed from the equation, and hopefully treated and cured, then the disease is also removed.

        It's a roundabout way to prevent infection, but it works! I like the thinking outside of the box. What's that old saying?: "An ounce of prevention is worth a pound of cure."

          Reply#4 - Thu Nov 15, 2012 6:12 AM EST

          and now for some good news

            Reply#5 - Thu Nov 15, 2012 6:43 AM EST
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