Transcript

INSTRUCTOR:

This is cephalosporin C, the first compound in one of the most important classes of beta-lactams-- the cephalosporins. It occurs in nature and was originally isolated from a fungus found growing in a sewage outlet in Sardinia in 1947. It's the lead compound from which a whole family of antibiotics has been made, but it isn't itself a particularly powerful antibiotic. Why? It all hinges in the way that antibiotics work. What they do is disrupt the process of cell wall biosynthesis. In a growing colony, this process is taking place all the time, both to maintain the existing cell wall and to make new wall as the bacteria divide.

When an antibiotic is added to a colony, this inhibitory action has two effects. Firstly, the bacteria are prevented from successfully dividing, so they start to form long, spaghetti-like strings. The other effect arises from the fact that the existing cell walls routinely break down and are in constant need of repair. As the process of repair is prevented, small flaws appear, large enough to allow water to start moving into the cell due to the high internal osmotic pressure. As a result, the cells start to swell and eventually burst, a process called lysis.