Antibiotic Therapy

Question 1

Bacteriostatic vs Bactericidal?

Answer 1

Static - stops growth (Chloramphenicol, erythromycin, clindamycin, sulphonamide, trimethoprim, tetracyclines)
Cidal - kills growth (aminoglycosides, beta lactams, vancomycin, quinolones, rifampin, metronidazole)

Question 2

Folic acid synthesis inhibitor?

Answer 2

Sulfamethoxazole

inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA).
Ttomethoprim blocks the production of tetrahydrofolic acid from dihydrofolic acid by binding to and reversibly inhibiting the required enzyme, dihydrofolate reductase.

Question 3

Why is tetrahydrofolate (THF) so important?

Answer 3

Purine, thymine, methionine blocks DNA synthesis and Protein synthesis, inhibiting transcription and translation

Question 4

DNA topoisomerases?

Answer 4

Fluoroquinolone
Quinolone

Topoisomerase unwind DNA for DNA replication. inhibition of this stops organism replicating not killing it

Question 5

DNA damage?

Answer 5

Metronidazole

Forms ROS
Formation of covalent metronidazole adducts with proteins involved in antioxidant defence is likely to render the cells more vulnerable to oxidative stress

Question 6

mRNA synthesis inhibition?

Answer 6

Rifampin

Targets RpoB of the RNA polymerase complex. inhibits transcription.

Question 7

Protein synthesis 50s 30s subunit

Answer 7

50s
macrolides
streptogramins

30s
aminoglycosides
tetracyclines