Can we fight “bad” bacteria without harming “good” bacteria?

By Guy Tsafnat - September 21, 2015, 4 PM

At any given moment, there are billions of bacteria living on each of us – on our skins, in our guts, noses, ears, mouths and anywhere else they manage to survive. Most of the time these bacteria are harmless or even beneficial, for example, by keeping harmful bacteria at bay. However, some have specific properties that make them able to turn pathogenic and make us sick and to resist antibiotics. Whether a bacteria is pathogenic or not depends largely on the genes that they carry.

Existing antibiotics don’t tell bacteria apart and so treating a disease can also kill the harmless and beneficial bacteria. Every time we take antibiotics, we also “help” the bacteria that are better at resisting antibiotics by taking out their competition. This, in turn, means that the resistance is increasing overall as the remaining resistant bacteria multiply. To avoid this from happening, it has been proposed that antibiotics that target just the harmful bacteria, if such could be developed, would alleviate the growing problem of antibiotic resistance. Several mechanisms have been proposed by the most likely ones are synthetic viruses (called bacteriophages) that attack specific locations in bacterial genomes, namely, the genes that make the bacteria pathogenic. One of the problems with this approach is that there are thousands of genes that make bacteria pathogenic and only a handful of them are enough to make disease both severe and highly resistant to conventional antibiotics. We therefore first need a lot of research on bacterial genomics to be able to rapidly test and quickly design personalized viruses for specific infections. Recent experiments show promise but a clinical application is still decades away.  

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