Antimicrobial Chemotherapy 6 - start of quinolones

Question 1

What is the mechanism of aminoglycoside-aminocyclitol (AGAC) antibiotics?

Answer 1

Gentamicin (aminoglycoside antibiotic)
- binds irreversibly to 30s ribosomal subunit
- stop translocation and stop protein synthesis
may
- generate errors in the translation of the genetic code
- affect bacterial membrane permeability

Spectinomycin (aminocyclitol) antibiotic
- binds to the 30s ribosomal subunit and inhibits protein synthesis
- bactericidal activity against some gram-positive and many gram-negative bacteria

Question 2

What is the mechanism of chloramphenicol?

Answer 2

Binds to the 50s ribosomal subunit and prevents attachment of tRNA to its acceptor site, thus preventing peptide bond formation
- bacteriostatic

Question 3

What is the mechanism of linezolid?

Answer 3

Binds to the 50s ribosomal subunit to block initiation phase of translation

Question 4

What is the mechanism of mupirocin?

Answer 4

Inhibits bacterial isoleucyl tRNA synthetase

Question 5

What is the role of DNA gyrase?

Answer 5

Relaxes positively supercoiled DNA
- by periodically breaking phosphodiester bonds in one of the strands of the double helix
- introducing negative supercoils
- resealing the nick