Antimicrobials by names

Question 1

Aminoglycosides (7)

Answer 1

1. Prevents translation of tRNA on 30s ribosomes = protein synthesis inhibition
2. gram -ve aerobes
3. Tx Nephro + oto
4. Tx horse clostridum overgrowth
5. adverse reaction with other drugs and ana
6. often used with B-lactum
7. ending in mycin

Question 2

Amphenicols

Answer 2

Bacteriostatic

Question 3

B-lactams

Answer 3

• • B-lactams all have a 4-sided B-lactam ring which bind to penicillin binding proteins
• • stops cross-linking of bacteria cell wall
• • triggers peptidoglycan breakdown
• bactericidal

Question 4

Bacitracin

Answer 4

• interferes with transport of peptidoglycan precursors across cytoplasmic membrane
• toxicity limits use to topical applications
• common ingredients in non-prescription first-aid ointments

Question 5

Cephalosporins

Answer 5

• hypersensitivity common

Question 6

Chloramphenicol

Answer 6

1. Binds to ribosome 50s which inhibits proteins interpeptide bonds
2. Tx = aplastic anemia
3. metabolised by the liver
4. effective againt gram + and -
5. effective in wide range (spirochetes and rickettsia)
6. Good penetration of blood brain barrier and eyes
7. often used as a last resort

Question 7

fluoroquinolones

Answer 7

1. Inhibiting bacterial DNA synthesis (Topoisomerase DNA gyrase, = not allowing supercoiling) = bactericide
2. Tx inhibiting cartilage growth in young animals
3. Tx cat retinopathy
4. Against wide range aerobic gram +ive and -ive (not anaerobes)
5. well tolerated in birds, reptiles and pocket pets (guinea pigs)
6. not registered in food production
7. ends in ‘floxacin’

• Note = new one called pradofloxacin which does spectrum gram + an - and Anaerobes

Question 8

Imidazoles

Answer 8

• Bactericidal
• inhibiting of nuclei acid synthesis

Question 9

Lincosamides

Answer 9

• Bacteriostatic

Question 10

Macrolides

Answer 10

• inhibits protein synthesis by inhibiting 50s ribosome
• bactericidal in high doses
• bacteriostatic in lower doses

Question 11

lincomycin

Answer 11

• inhibits protein synthesis by inhibiting 50s ribosome
• bactericidal in high doses
• bacteriostatic in lower doses
• eg clindamycin

Question 12

Penicillin

Answer 12

• hypersensitivity common

Question 13

Polymixins

Answer 13

• bind to phospholipids of gram -ve disrupting membrane (affects eukaryotes too, so only used topically) = inhibition of membrane fx
• bactericide
• often used in together with bacitracin

Question 14

Rifamycins

Answer 14

• inhibits RNA polymerase

Question 15

Sulphonamides

Answer 15

drug hypersensitivity in dobermans = delayed sulphonamide metabolism

Question 16

Tetracycline

Answer 16

• binds to 30s ribosomal subunit, blocking tRNA attachment
• affects gram +ve aerobes and gram -
• Bacteriostat
• Broad spectrum antibiotic
• Tx = impact bone growth
• Tx = teeth staining in young animals
• Tx = tissue necrosis at injection sites
• Tx = hepatic microsomal induction/inhibition
• Tx = adverse reactions with a aesthetics
• Tx = oesophageal strictures (doxycycline)
• Eg all end in cycline

newer eg doxycycline have longer half-life

used for intracellular bacteria (Chlamydia, mycoplasma, rickettsia)

Question 17

Tripmethoprim/sulphonamides

Answer 17

• Bactericidal in combinations
• bacteriostatic when given alone
• inhibitions of synthesis of essential metabolites
• Sulphonamides = competitive inhibition of enzymes
• Trimethoprim = blocks enzymes in folic acid synthesis (required for growth)
• Increased resistance so not used often by itself, for UTI
• Bacteriostats
• Toxicity = kerroconjuctivits sica with prolonged use
• Tx idiosyncratic hepatotoxicity in dogs
• Tx athropathies, cutaneous reactions and haemolytic anaemia
• Hypersensitivity reaction common

Question 18

Vancomycin

Answer 18

glycoproteins

• binds to the D-alanyl-Dalanine end of the peptidoglycan pentapeptide chain rather than to the PBP enzyme
• only effective against gram positive, as too large to enter gram negative membrane to get to cell wall
• “last line: against antibiotic resistant “s.aureus”

Question 19

Nitroimidazoles

Answer 19

• binds to and fragments DNA
• Particularly effective in anaerobes