As promised: Antibiotics are awesome!

Forget World War I.  The real great war is modern medicine.

The interesting thing about bacteria is that they're everywhere.  A large amount of human physiology and function depend on the tiny microbes co-inhabiting our bodies.  Now this may seem disgusting, but in truth, bacteria often get a bad rap.  They only become a problem in the classic case of "wrong place, wrong time".

Take for example the bacteria currently colonizing my sinus cavities.  These little guys probably aren't all bad.  Bacteria contribute to the natural functions of our eyes, our digestive tract, our reproductive tract, and even our skin.  The problem occurs when this natural biological ecology gets thrown out of balance.  This can generally happen through either overpopulation or when a rogue bacterium wanders into one of the regions of the body that is generally free of flora (enter my sinuses).

Okay okay... regardless of the bad rap, when we need to get healthy, where do we turn?  Thankfully, on a very basic level, bacteria are quite different from ourselves.  This may seem obvious, but the basic biochemistry decorating the exterior of the bacteria and the manners in which they protect themselves from the outside world are sufficiently divergent as to allow us to target them in a quite clever manner.

Augmentin is a combination of amoxicillin and clavulinic acid, a potent one-two punch that goes after the bacterial cell wall, which serves to protect the bacteria.  The cell wall also allows bacteria to sequester essential ions that provide for production of energy.  Without this energy, the bacteria cease to be.  Therefore, the goal of our drug is to halt the production of the cell wall.  Amoxicillin and clavulanic acid are able to accomplish this goal due to a close resemblance to a key portion of the cell wall, the D-alanine-D-alanine dipeptide:

Amoxicillin, like all members of the family of antibiotics known as beta-lactams, contains a characteristic moiety (shown below in red) that serves as a mimic of the terminal D-alanine-D-alanine.

Due to this resemblance, amoxicillin is able to bind to the active site of the enzymes responsible for synthesizing the bacterial cell wall - and quite well at that.  Through this binding, the enzymes are irreversibly shut off, causing a build-up of molecules that are precursors to the final cell wall.  These molecules then initiate the degradation of the wall, imitating conditions under which a cell wall would be reorganizing.

However, this was not the be all and the end all to this story.  The bacteria fought for their lives and found a manner in which to win.  By producing another enzyme called beta-lactamase, the bacteria are able to degrade the beta-lactam antibiotic before it is able to interfere with cell wall biogenesis.

Now enters clavulinic acid, shown here:

While clavulanic acid does contain the beta-lactam moiety (see red above), unlike amoxicillin it is not bactericidal in and of itself.  However, due to its structural proximity to antibiotic beta-lactams, clavulanic acid is able to inhibit the beta-lactamase enzymes that degrade the beta-lactam antibiotics that inhibit the enzymes responsible for the synthesis of the cell wall.

In essence, this chess match is why antibiotics are awesome.  When it comes to it, the bacteria have two options: to be killed or to adapt and become even more powerful than we could possibly imagine.  Both choices are made, but the antibiotic assures that only the strong survive and that the good (from a treatment standpoint) die young.  This is why there is such outcry against the overuse of antibiotics - while it does not *create* new superbugs, it does assure that the relative proportion of resistant bacteria is ever increasing.

Anyway, the complex layers upon layers of action and reaction are somewhat boggling to consider.  Who would have thought medicine would have so many tactics and tricks up its sleeves?

For the reader who desires to know more, I highly encourage a trip to Wikipedia.  Many of the terms - including the compounds discussed above - can be found there and in a fair amount of detail.  Given the references at the bottom of all Wikipedia entries, your descent further down the rabbit hole is entirely at your discretion.