Test for Viral Infections Could Cut Unneeded Antibiotics

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A new test can distinguish between respiratory infections caused by viruses and those caused by bacteria and other germs. The test identifies the unique signatures of the immune system as it fights viruses. 

"There's a very specific response we have to viruses, versus bacteria, versus other pathogens," said study co-author Dr. Geoffrey Ginsburg, a clinical genomics researcher at the Duke Institute for Genome Sciences and Policy in Durham, N.C. If widely adopted, the test, described today (Sept. 18) in the journal Science Translational Medicine, could help curb the overuse of antibiotics, the researchers said. Tough call When people come into the doctor's office complaining of coughs, chest congestion and a fever, it can be tricky to sort out whether bacteria or a virus is the culprit. Doctors may try to guess based on symptom severity, or ask patients to come back later if symptoms don't resolve. But they also may simply prescribe antibiotics, on the reasoning that it can't hurt. But those individual decisions have contributed to the rise of drug-resistant strains of bacteria, which killed 23,000 people last year, according to the Centers for Disease Control and Prevention.

Unique signature Ideally, doctors would like to know immediately whether a patient has a viral infection, which doesn't benefit from antibiotic treatment, or a bacterial infection, which may require the drugs. While tests for specific viruses exist, those aren't useful for most respiratory infections. Ginsburg's team wondered whether there was a more general way to discriminate between viral and bacterial infections. The team gave the influenza virus to 17 patients, and then looked at which genes were activated in their systems by detecting RNA circulating in their blood. (RNA is a chemical copy of the DNA of genes that are active.) The researchers then used those gene signatures to see if they could identify infections in a group of 102 people. Some people in the group had confirmed bacterial infections, others had viral infections and the rest were healthy. The team found that the body's response to the viral infection activated different genes than bacterial and other infections did.

The test identified about 90 percent of the people with viral infections, and wrongly flagged four people with bacterial infections and one healthy person. Preventing overuse The findings have incredibly significant implications, said Dr. Octavio Ramilo, an infectious-disease specialist at Nationwide Children's Hospital in Columbus, Ohio. "Nobody wants to take risks, so the tendency is to overuse antibiotics," Ramilo told LiveScience. Once doctors know for sure that someone's cough is viral, they will be less likely to overprescribe antibiotics, he said. The approach probably could be widened to include other conditions, such as pneumonia, which is often caused by a virus, Ramilo said. And because it uses a common technique already used in diagnostic testing, the new method could be easily adopted in the clinic, Ramilo added. Though the current test doesn't specifically identify bacterial infections, the team is doing late-stage development for a similar test for bacterial infections.

 

Written By: Tia Ghose
continue to source article at livescience.com

18 COMMENTS

    • In reply to #2 by test2:

      How much use is that, as long as antibiotics are given to healthy animals in bulk?
      Exactly. Doctors give anti-biotics all the time to virus sufferers because the patients expect it, not because doctor or patient thinks there is any chance it is a bacteria.

    • In reply to #2 by test2:

      How much use is that, as long as antibiotics are given to healthy animals in bulk?

      This is a huge problem, and is rarely addressed in the media or in legislation. I personally think that it should be strictly illegal to give antibiotics to livestock unless an animal is ill and the infectious organism has been undergone susceptibility tests to determine the correct antibiotic to use. Currently these drugs are not being used to treat or prevent illness – they’re used to promote growth and weight gain….at the risk of creating nightmarish superbugs that could wipe out the animals – and us. How stupid and shortsighted is that?

  1. A: The test shows it’s viral, so I can’t in good conscience give you an antibiotic,

    B: Am I getting anything?

    A: Nope. Bye!

    Human nature might not be happy with implementing this technology the way that we should, unless we make a competent use of antivirals. I don’t know much about them, but they hardly ever seem to be prescribed, so presumably they aren’t an effective option yet (at least not a cost-effective one).

    • The same problem applies to antiviral medications. Viruses, like the flu and HIV, mutate and become resistant to them. This is also why new vaccines for the flu must be made every year. The virus mutates so the antibodies the immune system created against it in response to the old vaccine don’t recognize it. Viruses also work differently than bacteria and are much more insidious. Bacteria proliferate on their own and cause symptoms due to their toxic metabolic by-products and tissue damage, as well as the extreme immune response this damage stimulates. Viruses can’t replicate on their own; they must invade cells and use their machinery to replicate. The only way to destroy the cellular viral factories is to destroy the cells – really not what you want. Antivirals work by blocking the receptors that allow viruses to lock onto cells and enter them. Those receptors easily mutate – hence the emerging antiviral resistance.
      The bugs have the benefit of hundreds of millions of years of natural selection in this arms race, while we have only a few decades of medical science under our belts. It’s a question of how much we can learn about their genetics and how fast we can implement it in order to stay ahead even for a moment. People need to know that overusing antibiotics and antivirals will only lead to worse infections that nothing can treat. Which would they rather have – a few days of the sniffles at home or drowning from a raging pneumonia in the hospital, while the doctors and their family watch helplessly?
      In reply to #4 by Jos Gibbons:

      A: The test shows it’s viral, so I can’t in good conscience give you an antibiotic,

      B: Am I getting anything?

      A: Nope. Bye!

      Human nature might not be happy with implementing this technology the way that we should, unless we make a competent use of antivirals. I don’t know much about them, but the…

      • In reply to #9 by Sue Blue:

        This is also why new vaccines for the flu must be made every year.

        I suspect that is not true. There are 256 possible flu strains. Which combination of them which show up each year can be guessed. I don’t think the flu itself is mutating. This information is based on an article I read long ago.

        HIV mutates within your body. Only the unmutated wild strain is strong enough to spread from person to person. My particular strain of HIV is immune to a dozen or more HIV drugs. I am using a drug that has not yet been released to deal with the problem. They monthly do a DNA sequence of my HIV to see which mutations it has. Which mutations confers immunity to which drugs is known. It takes only one mutation to knock out an entire drug class. The interesting thing is the HIV finds the same mutations independently in different people to find the immunity.

        You take a drug cocktail of 3+ drugs. The idea is it keeps the HIV count down low enough that it can’t do much mutating to find immunity to any of the three drugs. You must not skip a dose, or the HIV count will rise and the HIV gets do so some mutation space searching. Viruses don’t repair after reproduction so they have a much much higher mutation rate than bacteria or somatic cells.

        There are several advantages to getting an HIV+ person on drug treatment:

        1. their HIV is not the contagious wild type.
        2. their HIV loads are very low and hence unlikely to transmit
        3. HIV is kept at low levels, unable to do much damage.
        • In reply to #14 by Roedy:

          In reply to #9 by Sue Blue:

          This is also why new vaccines for the flu must be made every year.

          I suspect that is not true. There are 256 possible flu strains. Which combination of them which show up each year can be guessed. I don’t think the flu itself is mutating. This information is based on…

          Flu viruses have two glycoproteins, hemaglutinnin (H) and neuraminidase (N) on their surfaces that allow them to attach to and invade the epithelial cells of your respiratory tract. These mutate slightly over time (antigenic drift), meaning that your antibodies to the last strain of flu you encountered may not be as effective against the new strain. Every year, flu surveillance programs sample viral strains from around the world to determine what drift has taken place and which strains are most likely to cause epidemic illness, and new vaccines are developed. Sometimes the hemaglutinins and neuraminidases change their number or configuration so drastically that no one will be even partly immune to it. These events are called antigenic shifts, and they are the cause of pandemics, like H1N1. Flu viruses swap genes inside of animals like birds and pigs, creating new mosaic versions that may become virulent human pathogens. Thousands of scientists work full time around the world to try to stay one small step ahead of such developments, which have been observed and documented. That the flu virus mutates frequently, commonly, and quickly is not in any scientific doubt.
          Many people think that flu vaccines are some sort of government plot, especially if they get sick anyway. It is entirely possible to get the flu after having gotten a flu shot – it takes up to 2 weeks for your immune system to produce enough antibodies to fully protect you. Or you may contract a rare strain that was not accounted for in the vaccine. This year’s vaccine covers four strains that, by all available measures, will be the ones most likely to cause epidemic flu this fall and winter.
          The bugs have been at this game a long, long time. We are just beginning.

  2. I know people who will lie to get a prescription, they will simply find a new story. I also assume that it will take a day to get back the results. People will be ticked that they need to wait, pay for a test and not get anything in return.

  3. A short list of drug-resistant (read “damn-near untreatable”) infections that have emerged as a direct result of drug-imposed artificial selection (read “antibiotic/antiviral/antiparasitic” overuse):

    MRSA Methicillin-resistant staphylococcus aureus

    VRSA Vancomycin-resistant staphylococcus aureus

    VRE Vancomycin-resistant enterococcus

    Choloroquine/mefloquine-resistant Plasmodium falciparum (the deadliest form of malaria)

    Oseltamivir-resistant influenza (Tamiflu-resistant)

    Klebsiella pneumonia (a nearly drug-impervious bacterial pneumonia with an extremely high fatality rate)

    And those are just a few I can remember from my microbiology days a few years ago. As an RN, I see them frequently in the hospital, and some bugs are so impervious that even the most scrupulous scrubbing with industrial-strength disinfectants won’t destroy them. In order to rid their patient rooms of some staph, strep, and other bacteria, some hospitals have had to remove and destroy all furnishings and refinish all surfaces (tile, etc.).

    • In reply to #11 by Sue Blue:

      A short list of drug-resistant (read “damn-near untreatable”) infections that have emerged as a direct result of drug-imposed artificial selection (read “antibiotic/antiviral/antiparasitic” overuse):

      MRSA Methicillin-resistant staphylococcus aureus

      VRSA Vancomycin-resistant staphylococcus aureus…

      Oh, and add MDR-TB (multi-drug resistant tuberculosis) to that list. The old “white plague” is making a comeback.

    • In reply to #11 by Sue Blue:

      A short list of drug-resistant (read “damn-near untreatable”) infections that have emerged as a direct result of drug-imposed artificial selection (read “antibiotic/antiviral/antiparasitic” overuse):

      The catch is, you don’t want to create a gradient where tough bugs survive. You have to nail them 100% or you leave some superbugs behind. We have not seen bugs that beat an autoclave. We would if someone started fooling around with various low temperature autoclaves.

      • In reply to #15 by Roedy:

        In reply to #11 by Sue Blue:

        A short list of drug-resistant (read “damn-near untreatable”) infections that have emerged as a direct result of drug-imposed artificial selection (read “antibiotic/antiviral/antiparasitic” overuse):

        The catch is, you don’t want to create a gradient where tough bugs su…

        This is why susceptibility testing of infectious organisms before giving an antibiotic is so important. You pick a drug that is known to wipe out the selected bacteria, then blitz it. In the case of severe, fulminant infections like bacterial meningitis, there are broad-spectrum antibiotics that are given in high doses to decrease the bacterial load until specificity tests are complete. These powerful antibiotics have serious systemic side effects and are used only when necessary, in the hospital, and by IV only. The tragedy is that even these powerful drugs, such as vancomycin and some third-generation cephalosporins, are meeting resistance in some of the deadliest infections that cause endocarditis, meningitis, and necrotizing fasciitis. As a nurse, I have seen these infections, and read about them daily in the literature. You’d better believe we are in an all-out war for survival – our technology and science against nature. We have ratcheted-up the selection pressure on microbes to a screaming pitch, and they’re not backing down.

        And yes, there are some “bugs” that can withstand autoclaving. Prions, for example. They are the agent that causes SBE (aka “mad cow”) and CJD (Creutzfeldt-Jakob Disease). They are neither bacteria nor viruses but are abnormal versions of proteins normally found in neurons. Once present, nothing destroys them – not chemicals, heat, radiation, or anything available in a home or hospital setting. Scary stuff. There are also thermophilic bacteria that survive the extreme temperatures and acidity of hot springs and the superheated pressures of volcanic undersea vents. Microbes are the most versatile life forms on the planet.

  4. Pardon my ignorance, but what use are antibiotics against viral infections?

    Nothing, unless you are using them specifically to prevent secondary bacterial infection e.g. PCP in HIV/AIDS.

    What are anti-viral drugs called?

    Antivirals :P

    A: The test shows it’s viral, so I can’t in good conscience give you an antibiotic,

    B: Am I getting anything?

    A: Nope. Bye!

    Human nature might not be happy with implementing this technology the way that we should, unless we make a competent use of antivirals.

    I would have hoped it would reassure those who have viruses, rather than drive demand for a different antimicrobial. Looking at the abstract for the paper in question, I note they ‘experimentally induced’ influenza in healthy volunteers although I’ve not been able to access the full paper to see if it was done using vaccine components or actual live virus (seeing as one of the viruses tested was H1N1 ‘swine ‘flu’, live virus sounds a bit of an ethical stretch).

    A problem brought up in the article (early days, I know) is the false positive rate, specifically identifying those with bacterial infections as ‘viral.’ Note that the paper mentions comparing those with proven viral respiratory illness with those others (absolute number unstated in the abstract) who have systemic bacterial infection. Whilst the two might be confused clinically, I suspect the greatest use of a test like this will be if it can differentiate those who are not quite so sick.

    I don’t know much about them [antivirals], but they hardly ever seem to be prescribed, so presumably they aren’t an effective option yet (at least not a cost-effective one).

    Since viruses integrate into the host genome, antivirals generally inhibit specific viral protein products by interrupting DNA synthesis e.g. reverse transcriptase inhibitors in HIV, or by blocking release of new virus particles e.g. Tamiflu. The clearance of the virus i.e. killing of the remaining infected cells is down to the body’s own immune mechanisms which just takes time (assuming there is nowhere for the virus to hide or the cells infected aren’t particularly important – biiiiig problem in HIV). So you’re partially right, we have good ones for certain circumstances but for the rest, you’d get better fairly soon anyway, so why risk the side effects? (or the enormous drug development costs?)

    Doctors give anti-biotics all the time to virus sufferers because the patients expect it, not because doctor or patient thinks there is any chance it is a bacteria.

    One of the nice things about working for a publicly funded healthcare system is that I can truly work for my patient with a cold by telling them to MTFU, go home, take some paracetamol and stop coughing over me! :D

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