How does the staph superbug become so super?.
Our approach has been to take the isolates of staph from patients at the day they are diagnosed with an infection and then again 20 days later when they've failed therapy with vancomycin. Using DNA sequencing, we sequence the complete genome of the bacterium for the first and last isolates. We've found, for the first time, that you only need to change one tiny piece of the DNA - what we call a nucleotide, the minimum component of the DNA sequence of the microbe - and it's enough to allow the bug to reprogram itself, to make a slightly different cell wall, to do a few other different tricks that mean the antibiotic is not as effective any more. Worryingly, we also found this change also made staph more resistant to another last-line antibiotic, even though patients had never been treated with this agent. There are also examples of point mutations in bacteria causing antibiotic resistance but we've shown a new mechanism by which staph aureus can evolve resistance to vancomycin. We could use vancomycin in a different way or change the dosage; or find a partner drug so the bacteria have to develop resistance to two drugs - a common strategy to fight other infectious diseases; or identify patients more at risk of developing these resistant infections and treat them differently.
