Photo: Rob Brewer (flickr)
Unlike most drugs, antibiotics are made by microorganisms, such as bacteria. The antibiotics help those microorganisms survive by attacking other bacteria competing for the same food supply.
But to protect themselves, the bacteria producing antibiotics have to resist the effects of their own chemical defenses.
One way antibiotic-producing microorganisms avoid being killed is by producing what’s called a “resistance protein,” capable of inactivating the antibiotic.
When the antibiotic is released into the environment, it enters and kills other bacterial cells. Meanwhile, the resistance protein inactivates any of the antibiotic that gets back inside the microorganism it came from.
Modified Cell Structures
Another way in which antibiotic-producing microorganisms avoid suicide is by having modified cell structures that aren’t affected by the antibiotic they produce. In general, antibiotics work by interacting with very specific sites on, or within, bacterial cells.
The penicillin-type antibiotics, for example, work by interacting with certain specific proteins on the bacterial cell wall. Since most bacterial cell walls include those proteins, most bacteria are destroyed by penicillin.
So, to protect themselves from their own chemicals, the microorganisms that produce these drugs build their own cell walls without the proteins that the antibiotics work on.
By producing antibiotics, a microorganism is better able to compete for a limited supply of nutrients. But it’s only suicide if the microorganism can’t protect itself from its own antibiotic.