Wednesday, April 13, 2011

How Does It Work?: Penicillin

In the grand tradition of great sites like, I decided to start a regular feature with the terribly derivative title How Does It Work?  Why?  Well, because microbiology isn't confined to textbooks or research laboratories.  We interact with microbes every day.  We are carrying them in our guts, on our skin, inside our nose (yes, gross but true).  We eat and drink things that microbes help produce (bread and beer, for example).  Sometimes they help us and sometimes they hurt us.  So, it makes sense for us to know a little more about the different ways we study them and how we try to control them for our own purposes.

For our very first How Does It Work? today, I'll talk about the antibiotic penicillin, which was one of the first antibiotics discovered and then mass produced for treatment of bacterial infections.  Penicillin is credited with dramatically reducing the number of military deaths due to infection during World War II.  Although penicillin itself is not often prescribed these days, there are a number of antibiotics derived from penicillin that are still used in clinical therapy today, and these antibiotics work in the same general way as penicillin.

So, what is penicillin?  It is a chemical compound that is naturally produced by a fungus called Penicillium.  Below is a great picture of what Penicillium looks like under a microscope; the long filaments are called hyphae and the broom-like structures sprouting off from the hyphae are made up of columns of round spores.

Many of our antibiotics are derived from compounds produced by fungi or bacteria.  These compounds are the result of an evolutionary arms race between the different microbes that occupy the same environments.  In the case of Penicillium, this fungus lives in the soil, and it evolved to produce penicillin as a way of competing against other soil-dwelling microbes for resources.  Scientists discovered that what works for Penicillium can also work for us to combat bacterial infections.

How does penicillin work?  This may not be something you think about when you take an antibiotic.  Usually, we're just happy to take a pill and feel better.  But when you take your first course of an antibiotic, an incredible, microscopic drama starts to unfold within you.  Here's how it goes...