Future NZ: Good bugs, the future of medicine

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One of the key science questions of our time is how to beat bacteria in an age where antibiotics are no longer effective. Much like the "peak oil" crisis, the "peak antibiotic" point has likely transpired and, as a society, we are hesitant to even speak about what the medical equivalent of the clean energy revolution will be.

The outlook is both good and bad. The bad news is we can't beat them. The good news is that beating bacteria is not our only option. Bacterial cells out number the human cells in a healthy body by 10 to one. With a greater understanding of their role in our bodies, we will be able to harness their power to treat disease and promote good health.

Recent studies have suggested that people with more diverse populations of bacteria living in their guts are less prone to obesity, cardiovascular disease and diabetes. In addition, the one out of four individuals with low microbial diversity are more likely to gain weight and gain it more quickly than their high diversity friends.

More than being indicators of our tendencies, microbes may be directly engineering our metabolism or modifying the way our bodies encounter nutrients. In mouse studies, exchanging the microbes of a thin mouse for those from an obese mouse actually increased the mouse's weight without changing the diet.

In the future, we may be able to treat conditions like obesity and diabetes simply by adjusting the levels and diversity of microbes in our systems, rather than taking drugs. And this is just the beginning. There are hints that our microbes are sending chemical signals that affect our psychological and emotional function as well.

Scientists recently discovered that some soil microbes actually increase our levels of serotonin, a neuro-transmitter found to have a calming effect on temper and to increase intelligence. In the future it may be possible to take an asthma-style inhaler full of friendly uplifting microbes when you are having a bad day - instant warm fuzzies. Or imagine stopping off for a delicious fruit shake from a local stand with a microbial additive that will help you focus in class or get over that disastrous crush on your neighbour.

Another promising area of microbial research will see the return of a form of medicine that saved lives during the first half of the twentieth century from the United States to the Soviet Union and Georgia. Bacteriophages (phages for short) are viruses that seek out and destroy specific bacterial targets in order to replicate themselves. These entities have been the natural parasites of bacteria for billions of years and they are very good at it.

Phage therapy is the application of a cocktail of appropriate phages in order to combat specific bacteria. This is a medical treatment formerly applied to humans that lost wide acceptance in much of Western medicine due to an untrained start. The beauty of phages as medicine is three-fold. They are extremely specific to particular pathogens and can therefore be tailored to suit. They replicate themselves when they destroy their targets, enhancing effectiveness at the infection site. And when the infection is gone, they simply leave the system to be turned over naturally.

Despite these advantages, when antibiotics were found to be safe and effective mid-century phage therapy was dismissed outside of the Soviet block. Cold war era politics kept the lessons of appropriate phage use outside of the mainstream. In the future phage therapy will be approved for use in humans once again. Gone will be the days of taking an antibiotic with broad-spectrum killing of the important and beneficial microorganisms in our bodies. Infections will be handled by taking a small dose of your enemies' enemy.

Phages can also be useful in fighting serious infections caused by medical implants. Recently, it was found that various phages have co-evolved with animal hosts (including us) to provide a first-responder's style immune system. In the future, implants - ranging from hearts to hips - could be constructed using biomaterials that have natural adherence sites for beneficial phages.

There is no telling where tinkering with our microbial communities will take us. While some will no doubt continue to make us sick, the vast array of microbes on our planet may turn out to be the undiscovered rainforest of natural cures we have been searching for.

Dr Heather Hendrickson is a lecturer in Molecular Biosciences at Massey University.