Question: which bacteria do you believe does the greatest harm?

Lena Ciric answered on 12 Mar 2012:

Hi Georgina. Good question. I don’t have a straight answer, I’m afraid.

There are many dangerous bacteria that spring to mind – Staphylococcus aureus (including MRSA) and Pseudomonas causes lots of horrible infections; Clostridium difficile, Salmonella and Campylobacter can cause really grim infections in your gut; Streptococcus can cause pneumonia; Mycobacterium tuberculosis causes TB and kills up to 2 million people a year.

With the discovery of antibiotics we were able to treat most of these diseases and until recently they were only a real problem in developing countries where antibiotics were not easily available. Unfortunately we were a bit too enthusiastic with the use of antibiotics. Doctors prescribed them when they weren’t necessary and they are even available to buy without a prescription in some countries. This overuse has resulted in many bacteria becoming resistant to antibiotics. This is because the bacteria evolved new genes by mutation and then passed them around to other species. Clever, eh?

The current situation is not good as a lot of bacteria have become resistant to many antibiotics and we’re running out of options when it comes to treating diseases. There is some hope, though. The theory is that resistant bacteria grow slower than non-resistant, so if we don’t use antibiotics so much the non-resistant ones should win out!