Antibiotics Flashcards
Describe the mechanism of action of b-lactams
- B-lactam ring binds to the enzyme responsible for creating cross-links in peptidoglycan
- Can not synthesis new cell wall
- Bacteria constantly remodel cell was peptidoglycan content
- Degradation becomes greater than production
- Cell rapidly dies
Name an antibiotic which inhibits bacterial cell wall synthesis
-B-lactams, specifically penicillin and its derivatives
How do bacteria acquire resistance to b-lactams?
- Decreased penetration to target site
- Alteration of target enzyme
- Inactivation of antibiotic by bacterial enzyme
Name an antibiotic which inhibits bacterial transcription
-Rifamycins, specifically rifampicin
What is the mechanism of action of rifampicin?
-Binds to DNA:RNApol complex and sterically blocks elongation
How do cells acquire resistance to rifampicin?
-Mutation in the subunit of RNApol to which the drug binds
What are the clinical uses of rifampicin?
-TB and leprosy
What are the clinical uses of b-lactams?
-Strep skin and soft tissue infections
Name an antibiotic which inhibits bacterial protein synthesis
-Erythromycin
What is the mechanism of erythromycin?
- Binds to 50s ribosomal subunit and inhibits peptidyl transferase
- Interferes with translocation of a’a during translation
- Cell death
How do cells acquire resistance to erythromycin?
-Random mutation in peptidyl transferase
What is erythromycin used for?
-Staph infections
Name an antibiotic used in chemotherapy
-Methotraxate
What is the mechanism of action of methotraxate?
- Inhibits dihydrofolate
- Cannot produce folic acid
- Interferes with purine and prymidine synthesis
- Selective inhibition of highly proliferating cells
How do cells acquire resistance to methotrexate?
- Impaired drug transport
- Changes in drug metabolism
