Principles of Antimicrobial Use

Question 1

Bactericidal vs Bacteriostatic
(Hint: 6 vs 4)

Answer 1

Bactericidal:
1. Bacteria Cell Wall Inhibitors
2. Aminoglycosides
3. Fluoroquinolones
4. Cotrimoxazole
5. Polymyxins
6. Lipopeptides

Bacteriostatic:
1. Tetracyclines
2. Macrolides
3. Sulfonamides
4. Trimethoprim

Question 2

Food-drug interactions (Antibiotics and antifungals)

Answer 2

1. Tetracycline
2. Fluoroquinolone
3. Posaconazole and Itraconazole

Question 3

Oral administration available

Answer 3

Cell Wall Synthesis Inhibitor:
1. Penicillin V
2. Penicillinase Resistant Penicillins (Also Parenteral)
3. Aminopenicillins & Augmentin (Also Parenteral)
4. 1st and 2nd Gen Cephalosporin

Protein Synthesis Inhibitor:
1. Tetracyclines (Doxycycline also parenteral)
2. Neomycin
3. 50S Ribosomal Subunit Inhibitors (Also parenteral)

DNA Synthesis Inhibitor:
1. Fluoroquinolones (Also parenteral)
2. Cotrimoxazole (Also parenteral but oral more common)

Others:
Nitrofurantoin
Metronidazole

Question 4

Poor CSF penetration

Answer 4

1st and 2nd generation cephalosporins, Aminoglycoside, Macrolide, Clindamycin

Question 5

Renal Clearance

Answer 5

1. Cell Wall Synthesis Inhibitors (Except Ceftriaxone)
2. Aminoglycosides (Except Neomycin)
3. Others: Tetracycline, ciprofloxacin, nitrofurantoin, cotrimoxazole

Question 6

Drugs generally safe in pregnancy and lactation

Answer 6

Beta Lactams and Macrolides

Question 7

Caution drugs during pregnancy

Answer 7

Tetracyclines, fluoroquinolones, cotrimoxazole

Question 8

Drugs to be avoided in renal impairment

Answer 8

Aminoglycosides, High-dose Vancomycin, Sulfonamides

Question 9

Drugs to be avoided in hepatic impairment

Answer 9

Anti-TB agents (Pyrazinamide), Amoxicillin-clavulanate

Question 10

Immunocompromised patients should receive what kind of drugs and what kind of therapy

Answer 10

Bactericidal drugs and Combination therapy

Question 11

What should be done for severely ill patients when prescribing antibiotics?

Answer 11

Initiate active antibiotics ASAP and use broad spectrum coverage

Question 12

Poor CSF penetration

Answer 12

1st and 2nd generation cephalosporins, Aminoglycosides, Macrolides, Clindamycin

Question 13

Drugs used to treat CNS infections

Answer 13

Penicillins, 3rd to 4th generation cephalosporins, Meropenem, Vancomycin

Question 14

Drugs used for prostatitis

Answer 14

Ciprofloxacin and cotrimoxazole

Question 15

Concentration-dependent bacterial killing abx

Answer 15

Aminoglycosides, Fluoroquinolones, Metronidazole, Daptomycin

Question 16

Time-dependent killing abx with no persistent effect

Answer 16

Beta Lactams

Question 17

Time-dependent abx with persistent effect

Answer 17

Vancomycin, Tetracyclines, 50S Ribosomal Subunit inhibitors

Question 18

PK-PD targets for concentration-dependent bacterial killing

Answer 18

Optimized Peak/MIC ratio (Cmax = 8-10x MIC)

Question 19

PK-PD target for time dependent bacterial killing with no persistent effect

Answer 19

Optimize %T > MIC (40-70% of dosing interval above MIC)

Question 20

PK-PD target for time dependent bacterial killing with persistent effect

Answer 20

Optimize AUC:MIC ratio

Vancomycin - 400 to 600
Fluoroquinolone - >30 (+); >125 (-)

Question 20

PK-PD target for time dependent bacterial killing with persistent effect

Answer 20

Optimize AUC:MIC ratio

Vancomycin - 400 to 600
Fluoroquinolone - >30 (+); >125 (-)

Question 21

Abx with Prokinetic effect

Answer 21

Erythromycin

Question 22

PD interactions causing QTc prolongation

Answer 22

Macrolides, Fluoroquinolones, Azoles

Question 23

PD interactions causing Nephrotoxicity

Answer 23

Aminoglycosides, Vancomycin, Amphotericin B, Sulfonamides

Question 24

PD interactions causing myelosuppression

Answer 24

Cotrimoxazole, Linezolid

Question 25

PD interactions causing photosensitivity

Answer 25

Tetracyclines, Fluoroquinolones, Sulfonamides

Question 26

PD interactions causing serotonergic syndrome

Answer 26

Linezolid

Question 27

Antimicrobials with good bioavailability

Answer 27

Fluoroquinolones, metronidazole, Cotrimoxazole, Linezolid

Question 28

Common antibacterials NOT requiring renal dose adjustment

Answer 28

• Azithromycin • Cloxacillin • Ceftriaxone • Clindamycin • Doxycycline • Fusidic acid • Linezolid • Metronidazole • Tigecycline • Isoniazid • Rifampicin

Question 29

Common antibacterials that MAY REQUIRE dose adjustment in hepatic impairment

Answer 29

 Ceftriaxone  Clindamycin  Fusidic acid  Metronidazole  Rifampicin  Tigecycline