Question: do you think you could actuly find out that being restist to antibiotics actually makes bacteria unhealthy.

Jim Caryl answered on 23 Jun 2011:

Hi,

Absolutely, I already know that being resistant to some antibiotics can make my bacteria unhealthy, but the question is, do I see the same effect in different environments. When we conduct our initial experiments, we do it on a nutrient jelly, or a nutrient broth, that bacteria like to grow in. This is a slightly artificial environment, but is generally a good means of predicting how things might work in the body. In actual fact, when bacteria have to compete on your skin, they will be far more stressed as there will be your immune system, and the harsh environment of you skin, trying to attack them too. So the presence of an antibiotic resistance gene that makes bacteria ‘unhealthy’ leaves the bacteria will little choice, they can either be out-competed and lose the battle, or they can ditch the gene.

However, sometimes they choose to ditch the gene, but all they’ve really done is de-activated it. The de-activated version then means that the bacteria become competitive again (less ‘unhealthy’), and at a later date, should the encounter than antibiotic again, it won’t take long for one cell to re-activate the gene, and then it will be the major survivor!

So this is the other side of my work, figuring out how bacteria can come up with strategies to keep hold of all their genes that make them resistant to antibiotics, without it actually making them unhealthy. If these strategies are something we can understand, we can also figure out how to disrupt them, so they are forced to get rid of the genes.