Antibiotics Lecture 33

Question 1

Fluoroquinolones
Mechanism 
Cidal or Static
Drugs 
MOR

Answer 1

Inhibit topoisomerase 2 and 4

Cidal- concentration dependent

Ciprofloxacin(old)
Levofloxacin
Moxifloxacin(CSF)
Gemifloxacin

MOR:

1. chromosome-encoded mutation in DNA gyrase or 4
2. plasma-mediated resistance
3. efflux pumps

Question 2

Which fluoroquinolones treat gram positive aerobes?

Answer 2

levo, moxi, gemi

Question 3

Which fluoroquinolones treat gram negative aerobes?

Answer 3

cipro=levo>moxi

Question 4

Which fluoroquinolones treat pseudomonas?

Answer 4

cipro>levo

Question 5

Which fluoroquinolones treat anaerobes?

Answer 5

moxi

Question 6

What do they all treat?

Answer 6

atypical bacteria

Question 7

What are the clinical uses of fluoroquinolones?

Answer 7

1. Pneumonia 
CAP: levo, moxi, gemi
HCAP: cipro(add gram coverage), levo 
2. Sinusitis, Bronchitis-all
3. UTI , prostatitis: 
cipro and levi 
4. Bone infections, STDs, TB, intraabdominal coverage with added anaerobe coverage

Question 8

What are the adverse effects of fluoroquinolones?

Answer 8

1. GI and CNS
2. Prolonged QTc interval
3. tendonitis, tendon rupture
4. hepatotoxicity, photosensitivity , rash, articular damage

-contraindicated in women and children

Question 9

What interacts with fluoroquinolones?

Answer 9

• Divalent, trivalent cations

- Warfarin, cyclosporine, theophylline

Question 10

Which fluoroquinolone doesn’t do gram positive?

Answer 10

Cipro

Question 11

Metronidazole
MOA
Cidal or static
MOR

Answer 11

Forms toxic free radical metabolites, inhibit DNA synthesis
ANAEROBIC INFECTIONS!

Concentration dependent cidal

MOR

1. Altered growth requirements-higher O2–>decreased activation of met
2. altered ferredoxin levels-less activation of met

Question 12

What do you use metronidazole for? DOes it penetrate CSF?

Answer 12

Anaerobic infections

• Intraabdominal, pelvic, diabetic foot , decubitus ulcer, brain abscess
• c-diff (IV or PO)

1. Bacteroides spp (all)
2. Clostridium spp (all)
3. trichomonas

*Penetrates CSF

Question 13

What are the side effects of Metronidazole?

Answer 13

1. stomatitis, metallic state
2. peripheral neuropathy
3. avoid during pregnancy and breastfeeding
4. drug interactions
   warfarin-increase anticoag effect
   alcohol-disulfiram reaction