• Question: why do viruses become resistant to antibiotics?

    Asked by imallthatx to Cat, Daz, Holly, Johnson, Pamela on 21 Jun 2011.
    • Photo: Pamela Lithgow

      Pamela Lithgow answered on 21 Jun 2011:

      Hi imallthatx,
      Bacteria become resistant to antibiotics and viruses to antivirals or other drugs because they change the things which those drugs work on. Bacteria and viruses “evolve” very quickly, what they do is make mistakes when they copy themselves this leads to a slightly different bacteria or virus. If there is a drug that is harming the bacteria or virus then sometimes one of this different copies is resistant to the drug and then that one grows and you get a whole lot that are resistant.
      I hope that helps
      Pam 🙂

    • Photo: Darren Braddick

      Darren Braddick answered on 21 Jun 2011:

      Hi imallthatx!

      Nice chatting earlier. Well the reason is kinda like Pam said, and how I said in the live chat. When they copy themselves they use enzymes (called polymerases) which basically make DNA but putting it together piece by piece. It needs a template to do this, so its basically a copy mechanism, a bit like tracing your writing on thin paper. Now, this process happens in all life – bacteria, plants, animals and humans, and usually is designed to be very very accurate. However, viruses are small, and their total DNA is very small compared to ours. This enzymes (the polymerases) are also different – they make many many mistakes.

      These mistakes change the sequence of DNA a lot. The DNA is needed to make the protein, and protein makes the virus and everything about the virus. So if you change the DNA, your alter the protein – and usually it is those proteins which our drugs (antibiotics) will target.

      Thus, you get very frequent changes in the protein – our target for antibiotics, and that is why you generate resistance. HIV, for example is very very good at adapting to survive our drugs.

      As Pam says, what happens next is that the ‘more resistant’ copies will survive better, and eventually the ‘less resistant’ ones will die and the ‘more resistant’ go from being a single copy or a small number to being the whole lot! So all the viruses end up resistant.

      This is true too for bacteria!

      I hope this answer helps 🙂

      Daz

    • Photo: Cat O'Connor

      Cat O'Connor answered on 21 Jun 2011:

      Wow great answers by Pam and Daz there, no need for me to say anything else really 😀

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