BIO 274 Chapter #20: Antibiotics

the “magic bullet” concept

Paul ehrlick - drugs should selectively target microbes and not humans

The first antibiotic

Penicillin discovered by Alexander Fleming

Antibiotic

substance produced by microbes that inhibits/kills other microbes?

Why are antibiotics with a very broad spectrum of activity not as useful as one might think?

Because they can cause a suprainfection where it kills so much of the normal microbiota that other bacteria overtake once everything is dead.

What is a superinfection?

overgrowth of ressitant microbes when normal microbiota are supressed

Targets of Antimicrobial drugs

1. cell wall synthesis inhibitors

2. protein synthesis inhibitors

3. Nucleic acid synthesis inhibitors

4. plasma membrane injury

5. metabolic pathway inhibitors

How does a metabolic pathway inhibitors (antimetabolites) work?

Block folic acid synthesis

How does plasma membrane injury work?

Can affect host cells too - more toxic

How do Protein synthesis inhibitors work?

Target 70s ribosomes (bacteria), not 80’s ribosomes (eukaryotes)