• Question: Why are bacterial spores a problem in sterilizing instruments and equipment?

    Asked by luxiliu to Cat, Daz on 24 Jun 2011.
    • Photo: Darren Braddick

      Darren Braddick answered on 24 Jun 2011:

      Hi Luxiliu!

      Well some spores are very very resistant to the things we can kill normal bacteria with! Usually we could use antibiotics or alcohols or heat to sterilize things, depending on what the instruments and equipment are made from.

      So these treatments will usually kill bacteria, because bacteria suffer from pressure and temperature easily, because their insides are watery and under quite high pressure. If you break or expand them, they will burst and that is how we usually kill them. Antibiotics damage the outside so the pressure bursts them, heat probably destroys them by unfolding proteins.

      So, in bacterial spores there is some kind of protection against these things – I think there is a shell around them which protects against all of these things. But with this shell, they can’t live and act like normal because they can’t grow or divide! They are completely dormant, and from this point, some things can cause them to wake up again, and they will be living and active again.

      The problem exists because the spores can survive the treatments, but bacteria will not. If we then assume that they are sterile, the spores may come alive again and then the instruments we have are contaminated with bacteria again.

      I hope this answers your question 🙂


    • Photo: Cat O'Connor

      Cat O'Connor answered on 24 Jun 2011:

      Hi Luxiliu,

      Some bacterial spores are a problem because they can survive really high temperatures because of their super resistant coat or shell they put up around themselves. They do this so they can survive times when there is no food or when conditions are not right for them to live…such as if the temperature was too hot or too cold!

      So we need to make sure that we use special temperature or special chemicals to kill the bugs that survive normal sterilisation!

      In all micro labs, we use an instrument called an autoclave which sterilises equipment and media (food for growing bugs in) at very high temperatures and very high pressures to make sure we kill the spores!

      Hope this answers your question!