Antimicrobials

Question 1

POTASSIUM PENICILLIN G: Family, MoA, -Cidal/Static?

Answer 1

Beta lactam Cidal Inhibits peptidases (enzymes that link amino acids together). Will therefore inhibit cell wall synthesis

Question 2

POTASSIUM PENICILLIN G: Spectrum of Act. & Cross Cell membrane?

Answer 2

Gm POS and most gm NEG aerobic cocci Not effective against gm NEG rods ; Anerobes; ( not B. fragilis, which produces β-lactamase) Poor (weak acids with charge

Question 3

CEFTIOFUR SODIUM: Family, MoA, -Cidal/Static?

Answer 3

Beta lactam Cidal Inhibits peptidases (enzymes that link amino acids together). Will therefore inhibit cell wall synthesis

Question 4

CEFTIOFUR SODIUM: Spectrum of Act. & Cross Cell membrane?

Answer 4

Gm POS and most gm NEG (more than pen) aerobic cocci Not effective against gm NEG rods ; Anerobes; ( not B. fragilis, which produces β-lactamase) Poor, no CNS

Question 5

AMPICILLIN SODIUM: Family, MoA, -Cidal/Static?

Answer 5

Beta lactam Cidal Better able to penetrate G- outer layer, Inhibits peptidases (enzymes that link amino acids together). Will therefore inhibit cell wall synthesis

Question 6

AMPICILLIN SODIUM: Spectrum of Act. & Cross Cell membrane?

Answer 6

Like penicillin, but more gm NEG spectrum Poor (weak acids with charge

Question 7

GENTAMICIN/Amikacin: Family, MoA, -Cidal/Static?

Answer 7

Aminoglycoside Cidal Irreversibly binds the 30S ribosomal subunit (inhibits translation, i.e. protein synthesis)

Question 8

GENTAMICIN/Amikacin: Spectrum of Act. & Cross Cell membrane?

Answer 8

Gm NEG aerobes , Staphylococci, no anaerobes Poor (polar)

Question 9

Oxytetracycline:Family, MoA, -Cidal/Static?

Answer 9

Tetracyclines Static “Reversibly binds the 30S ribosomal subunit (inhibits translation,
i.e. protein synthesis)”

Question 10

Oxytetracycline: Spectrum of Act. & Cross Cell membrane?

Answer 10

BROAD AEROBIC Some anaerobes Rickettsia Ehrlichia Good, NO CNS

Question 11

TRIMETHOPRIM-SULFA: Family, MoA, -Cidal/Static?

Answer 11

Potentiated sulfa (cidal in combination) Problems with resistance Cidal in combo Inhibits folic acid (FA) synthesis. Bacteria require FA to make purine DNA bases Trimethoprim competitively inhibits dihydrofolate reductase Sulphadiazine substitutes for para- amino benzoic acid (PABA) as it is converted to dihyrofolate.

Question 12

TRIMETHOPRIM-SULFA: Spectrum of Act. & Cross Cell membrane?

Answer 12

BROAD AEROBIC Few obligate anaerobes Protozoa Fair (hydrophilic; sulfonamides are weak acids)

Question 13

METRONIDAZOLE:Family, MoA, -Cidal/Static?

Answer 13

Cidal Readily taken up by bacteria and reduced to cytotoxic derivatives which damage DNA and other macromolecules. Not reduced by aerobes

Question 14

METRONIDAZOLE: Spectrum of Act. & Cross Cell membrane?

Answer 14

ANAEROBES (including Bacteroides and Clostridia) Protozoa Good (lipid-soluble)

Question 15

CHLORAMPHENICOL: Family, MoA, -Cidal/Static?

Answer 15

Static Reversibly binds the 50S ribosomal subunit (inhibits translation, i.e. protein synthesis)

Question 16

CHLORAMPHENICOL: Spectrum of Act. & Cross Cell membrane?

Answer 16

AEROBES Some anaerobes Rickettsia Excellent (lipid-soluble)

Question 17

ERYTHROMYCIN/Clar/Tulath(rum.): Family, MoA, -Cidal/Static?

Answer 17

Macrolides (cidal or static depending upon concentration) “Reversibly binds the 50S ribosomal subunit (inhibits translation, i.e. protein synthesis) NOTE:
Hyperthermia occurs occasionally in foals treated with erythromycin (seizures) “

Question 18

ERYTHROMYCIN/Clar/Tulath(rum.): Spectrum of Act. & Cross Cell membrane?

Answer 18

“More effective in gm POS Some gram NEG R. equi

“ Fair, (weak base)

Question 19

ENROFLOXACIN: Family, MoA, -Cidal/Static?

Answer 19

Fluoroquinolone Cidal Inhibit topoisomerase DNA gyrase. This enzyme supercoils bacterial DNA

Question 20

ENROFLOXACIN: Spectrum of Act. & Cross Cell membrane?

Answer 20

AEROBES, No anaerobes Poor against Streptococci Good (lipid-soluble)

Question 21

RIFAMPIN: Family, MoA, -Cidal/Static?

Answer 21

Cidal Inhibits DNA dependent RNA polymerase which synthesizes mRNA

Question 22

RIFAMPIN: Spectrum of Act. & Cross Cell membrane?

Answer 22

Most gm POS Some gm NEG Some anaerobes Mycobacterium Good (lipid-soluble)

Question 23

POLYMIXIN B: Family, MoA, -Cidal/Static?

Answer 23

Cidal Detergent-like properties (disrupt cell membranes and cause leakage). Binds lipid A region of endotoxin as it circulates

Question 24

POLYMIXIN B: Spectrum of Act. & Cross Cell membrane?

Answer 24

Gm NEG