Antibiotics

Question 0

Disrupt cell membranes by binding to membrane phospholipids –> structural disorganization. Maybe nephro/neurotoxic

Answer 0

Polymixin B&E , topical

Question 1

Mainly against active growing gram positives, prevent cross linking of peptidoglycan chains so bad cell wall synthesis

Answer 1

Penicillin & cephalosporins

Question 2

Block 30S ribosomal activity against gram negative bacteria. Nephrotoxic and ototoxic

Answer 2

Aminoglycosides - Streptomycin & Neomycin

Question 3

Block 30S by not blocking tRNA binding

Answer 3

Tetracyclines : macrolides

Question 4

Block 50S ribosomal activity

Answer 4

Chloramphenicol

Question 5

Block 50S; Contraindicated in horses & neonates

Answer 5

Lincosamides

Question 6

Block 50S activity, mainly against gram positives and some mycoplasmal pathogens

Answer 6

Macrolides : erythromycin & tylosin

Question 7

Block DNA directed RNA polymerase, inhibits transcription, antimycobacterial ( use with erythromycin for R. Equi Tx)

Answer 7

Rifampins

Question 8

Block DNA gyrase, no DNA unwinding, no replication. Use for mastitis Tx

Answer 8

Novobiocin

Question 9

Blocks DNA gyrase, Tx of enteric infections and intracellular pathogens

Answer 9

Quinolones (enrofloxacin), nalidixic acid

Question 10

Block pathway of making folic acid

Answer 10

Sulfonamides

Question 11

Combines with enzyme dihydrofolate to block nucleic acid synthesis

Answer 11

Trimethoprim

Question 12

Antibiotic synergism - two pairs

Answer 12

Penicillins & Aminoglycosides (inhibit cell wall synthesis & allow aminoglycosides entry)
- Sulfonamides & Trimethoprim (inhibit frolic acid synthesis, work together)

Question 13

Antibiotic antagonism (one pair)

Answer 13

Penicillin & bacteriostatic antibiotics (penicillin acts in cell walls of growing bacteria, doesn’t work if growth stops)