Antibiotics

Question 1

Beta lactam penicillins examples and MOA

Answer 1

Flucloxacillin and amoxicillin

Attaches to penicillin binding proteins on forming bacterial cell walls
Inhibits transpeptidase which cross links cell wall –> bacterial cell autolysis

Question 2

Cephalosporins

Answer 2

Ceftriaxone and cephalexin

Attaches to penicillin binding proteins on forming bacterial cell walls
Inhibits transpeptidase which cross links cell wall –> bacterial cell autolysis

Less susceptible to beta-lactamases than penicillins

Question 3

Glycopeptides

Answer 3

Vancomycin

Bactericidal
Inhibits cell wall synthesis of gram positive bacteria

Question 4

Aminoglycosides

Answer 4

Gentamicin

Binds to 30s ribosomal subunit
Inhibits protein synthesis –> prolonged post antibiotic bacteriostatic effect
Bactericidal action on cell wall
Synergistic with other abx

Question 5

Indications for gentamicin?

Answer 5

Severe gram negative infections e.g. pyelonephritis and hospital acquired pneumonia

Question 6

Quinolones

Answer 6

Ciprofloxacin

Interferes with bacterial DNA replication and repair
Broad spectrum bactericidal antibiotics - provides gram pos and neg cover

Question 7

Ciprofloxacin indications

Answer 7

UTI, gonorrhoea, RTI, prostatitis

Question 8

Macrolides

Answer 8

Clarithromycin + erythromycin

Bacteriostatic + bacteriocidal

Binds to 50s ribosomal subunit
Inhibits bacterial protein synthesis

Question 9

Macrolides indications

Answer 9

H.pylori, severe CAP, lyme disease

Question 10

Inhibitors of folate synthesis

Answer 10

Trimethroprim

Inhibits folate metabolism pathway -> impaired nucleotide synthesis
Interferes with bacterial DNA synthesis

Question 11

Antibiotics associated with c.diff?

Answer 11

Quinolones - ciprofloxacin

Cephalosporins - ceftriaxone + cephalexin