MRSA Image Source

The thumbnail image above is of an agar bacteria plate, and the light colored streaks you see upon it are a bunch of bacterial colonies (millions and millions of bacteria). This particular agar plate has been treated with oxacillin:

Source: This is the molecular structure of Oxacillin.

The bacteria that is growing on that plate is Staphylococcus aureus (aka Staph, the causative bacteria that results in a “staph infection.”) S. aureus are un-treatable by standard penicillin derived antibiotics because they have an enzyme called penicillinase which breaks these compounds down. Oxacillin and the similar Methicillin were historically used instead to kill S. aureus. However, you have likely already noticed that the S. aureus growing on that plate above don’t seem to mind the presence of the Oxacillin antibiotic. You are also likely very familiar with the name given to this sort of S. aureus, it’s called MRSA (which stands for Methicillin Resistant Staphylococcus Aureus). This and other bacteria like it pose an issue for our health and the health of our loved ones because without being able to use Oxacillin (or other antibiotics similar to it) we really don’t have many other highly effective ways to treat the infection.

Why Are We Running Out of Antibiotic Options?

Money. The large pharmaceuticals are profit driven businesses, they just don’t get a large return out of focusing on antibiotic research. After all you can only be administered these drugs for a short period of time until they beat back the infection and you no longer need them! Pharma prefers boner pills, opioid pain meds, or anti HIV treatments, you know chronic issues that necessitate taking a medication to deal with them indefinitely (they gotta drain you of your money after all). An unfortunate side effect of this profit driven business model is that areas that lack that financial incentive seem to get largely ignored. One of those areas is and has been the search for new antibiotics.

On The Bright Side We Aren’t Only Dependent on Pharma For New Antibiotics

There are still a variety of academic researchers who are focusing on these sorts of tasks as well. Recently some interesting potential compounds have come out of studying the organism’s that make up our microbiome. Before we talk about the new research, let’s discuss what the microbiome is to begin with, as it’s a flashy term that has been popping up even in mainstream news for a while now!

The Microbiome

When scientists talk about the human microbiome, what they are really talking about is the collection of all of the genomes from all microbial organisms which reside both on and inside the human body. Just how many bacteria are in the human body? Well, as little as 10 years ago scientists believed that our bodies contained as many as 10 bacterial cells for every human cell (and our bodies contain on average 30 trillion human cells), however this has recently been shown to be a myth and the number has been re-estimated to about 1 bacterial cell for every human cell (I guess that means we are all only half human…a significant upgrade from before when we were thought to be only 9.1% human) (3). What you should take from this information is that there are a TON of bacterial cells in and on the human body, and there is actually a surprising variety of different organisms all living symbiotically (together in harmony):

Source your body and its bacteria celebrating their symbiosis.

Since there are so many different microorganisms present, the number of different genomes is also massive! This means there are potentially many biological “treasures” to be found from studying it.

Humimycins

One of the first treasures to have come out of all of the data generated by human microbiome analysis comes from an article recently published in Nature Chemical Biology where the authors describe the identification and synthesis of a new class of antibiotics called humimycins. This antibiotic functions by inhibiting an enzyme called a lipid II flipase. Flipases are enzymes which are involved in the shuttling of lipids (fatty acid molecules) and are responsible for maintaining the composition of the cellular phospholipid bylayer. By inhibiting this enzyme class, humimycins are able to stop S. aureus from proper maintenance of its cell membrane, and lead to its death. This is a totally separate mechanism from how the Oxacillin like molecules function (they also work by messing with a part of the bacterial cell membrane, but through a different mechanism). Humimycins are also not susceptible to degradation through the pathway which allows MRSA to resist the Oxacillin antibiotics (cleavage of the antibiotics β-lactam ring by the bacterial β-lactamase enzyme), so this new antibiotic could prove very useful in the treatment of these and other antibiotic resistant bacterial strains.

Hope For The Future

Results like these give me hope (I hope they do the same for you) for the identification of more beneficial compounds. Who knows, maybe the next great antibiotic, allergy medication, or even obesity treatment could be found in some of the bacteria living in your body. We are host to so many different organisms and we need them for a healthy life as much as they need us. Going forward maybe we will find that to identify some of the most effective treatments we just needed to look within ourselves. Call it, cellular introspection if you will.

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Referenced Materials

1. https://en.wikipedia.org/wiki/Oxacillin
2. https://en.wikipedia.org/wiki/Human_microbiota
3. http://www.nature.com/news/scientists-bust-myth-that-our-bodies-have-more-bacteria-than-human-cells-1.19136
4. http://news.nationalgeographic.com/2016/01/160111-microbiome-estimate-count-ratio-human-health-science/
5. http://www.nature.com/nchembio/journal/vaop/ncurrent/full/nchembio.2207.html

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