Question: Is there a way to get rid of bacteria completely?

Jim Caryl answered on 23 Jun 2011:

Unfortunately not. Even with the use of an antibiotic that works very well on a particualr bacteria, you will not kill every single cell. This is because even if bacteria don’t have genes that make them resistant to that particualr antibiotic, there are certain aspects of their lifestyle that can also make the resistant. We call this ‘tolerance’, or ‘indifference’ or ‘persistence’.

These are all slightly different mechanisms that achieve the same aim – some cells will survive. The most common example, ‘indifference’, comes about because most antibiotics are designed to kill bacteria while they are actively growing. But if the bacteria are actually not growing, or they are ‘asleep/dormant’, then the antibiotic doesn’t really harm them.

In healthy people this isn’t *usually* a problem. All antibiotics are designed to do is to reduce the bacteria causing the infection to a point where your own immune cells can then fight them off. It is always your immune system that gets rid of an infection, the antibiotics just help it get there before the infection gets out of control. However, people who are very ill, with diseases such as cancer, or AIDS, and the very old and very young, all have compromised immune systems (their own defences don’t work very well).

So some of our collaborators are working on new antibiotics that are targeted specifically at these particualr bacteria, the ones that are ‘avoiding’ being killed by existing in a different lifestyle.