Low-Hanging Fruit

What do you do after you've picked all the low-hanging fruit?

The ground shifted beneath our feet yesterday with the release of the World Health Organization Report warning us that we’re entering a post-antibiotic era in which common infections and minor injuries which have been treatable for decades can once again kill. That’s because antibiotics have become increasingly ineffective due to chronic overuse over the past 70 years in both medicine and agriculture. It’s simply evolution at work: the more you try to kill a microbe with antibiotics the more it will evolve to not be killed by it. Hence the development of MRSA, which has hundreds of known mutations and has even begun to defeat drugs of last resort which have previously been able to treat it – but no more.

So the WHO report understandably received worldwide attention yesterday. A common thread throughout the coverage was to offer this solution: “[G]overnments have to find ways to encourage research and development into new antibiotics … given that pharmaceutical companies don’t have a financial incentive to develop new drugs for infections that just last for a week or two,” as the CBC reported on the National.

However, the assumption that new antibiotics can be found given sufficient time, money, and government support turns out to be a tragically flawed one because there may not be any more antibiotics to be discovered.

Dr. Gerry Wright, an infectious disease expert at McMaster University, in an interview with CBC’s science program Quirks and Quarks, explains the problem this way: Antibiotics exist in nature, mostly in organisms found in the soil. Yes, you have to extract from these organisms the molecule with the antibiotic property, and that means scientists working in their labs. But the active ingredient that becomes the antibiotic is a naturally occurring one, and therein lies the rub: we have taken from nature all the molecules known to exist that have antibiotic properties. That’s why no new classes of antibiotics have been developed since the 80s; all we’ve done since then is find the same kind of molecules over and over again. In other words, we have long-since picked all the low-hanging fruit.

These magic molecules that exist in nature and exhibit antibiotic properties are hard to come by because they have to be able to do something very special: they have to kill bacterial cells but not human cells – they have to be toxic to bacteria but not toxic to us. Remember, bacteria are “us” in the sense that we have 10 times as many naturally occurring bacterial cells in our body than we do human cells. So the line between destroying a bacterial cell wall versus a human cell wall is a fine one. That’s why antibiotics of “last resort” are given that ominous sounding name – because they attack us along with the bacteria, and so it becomes a war of attrition within to see which side is left standing.

So if all the low-hanging antibiotic fruit has been picked, where does that leave us? How about “Bio-prospecting” – looking for antibiotic molecules in remote locations like caves, rain forests, and the ocean floor. That’s something Dr. Wright does and he concedes nothing is on the horizon.

So where that really leaves us is turning to prevention strategies through better hygiene and other infection control practices such as decolonization, especially in health-care facilities. The sooner we plant those seeds, the sooner we bear our treatment fruit of the future.

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