C18

Question 1

MISCELLANEOUS ANTIMICROBIAL
AGENTS?

Answer 1

Metronidazole
Fidaxomicin
Rifaximin

Question 2

Metronidazole MOA?

Answer 2

• undergoes a reductive bioactivation of their nitro group by ferredoxin (present in anaerobic parasites) to form reactive cytotoxic products that interfere with nucleic acid synthesis

Distrupts electron transport

Question 3

Metronidazole PharmacoKinetix?

Answer 3

• bioavailability: effective orally
• Distribution: to most tissues (also CNS)
• can also be given I.V
• available in topical formulations
• Elimination: hepatic metabolism
• dosage reduction may be needed in patients with liver dysfunction

Question 4

MEtronidazole Clinical use?

Answer 4

1. Anarobic bacterial infections
2. Clostridium difficile colitis

Bactericidal vs anaerobes and certain protozoa

(trichomoniasis

• giardiasis
• intestinal amebiasis
• amebic hepatic abscess)

AntiBacterial:
- greatest activity against Bacteroides and Clostridium

• against pseudomembranous colitis
• effective in anaerobic or mixed intra-abdominal infections and in brain abscess
• used in the regimens for the eradication of Helicobacter pylori in gastric ulcers

Question 5

Metronidazole toxicity?

Answer 5

• gastrointestinal upset
• Neuropathy (seizures, headache)
• leukopenia
• Opportunistic fungal infections
• Drug interactions: potentiation of coumarin anticoagulant effects

Question 6

Fidaxomicinn MOA?

Answer 6

• narrow-spectrum
• antibiotic that is active against G+ aerobes and anaerobes
• inhibits bacterial RNA polymerase

bactericidalll

Question 7

Fidaxomycin Clinical uses and toxicity?

Answer 7

• used orally for C difficile infection in adults
• Toxicity is negligible due to limited absorptio (ZERO)

Question 8

Rifaximin MOA?

Answer 8

• derivative of rifampin
• it is active against G+ and G- aerobes and anaerobes
• inhibits DNA-dependent RNA polymerase

Bactericidal

Question 9

Rifaximin Clinical use?

Answer 9

ZERO absorption used orally for :

1. hepatic encephalopathy
2. irritable bowel syndrome with diarrhea
3. adjunct in cases of refractory C difficile infection in adults

Question 10

Rifaximin Toxicity?

Answer 10

negligible due to limited absorption

Question 11

pharma of abdominal infections

appendicitis treatment

Answer 11

• 1st line:
  
  • Ceftriaxone (I.V)
  • Metronidazole. oral, I.V
• 2nd line
  
  • gentamycin IV
  • metronidazole oral, I.V

Question 12

cholecystitis

Answer 12

• 1st line
  
  • Ceftriaxone i.v
  • ampicillin I,V
• 2nd line
  
  • Ciprofloxacin oral/ i.v
  • vancomycin I.V

Question 13

diverticulitis treatment

Answer 13

• mild-moderate:
  
  • 1st line : TMP/SMX oral
  • 2ND line:
    
    • ciprofloxacin oral
    • Metronidazole oral
• severe
  
  • 1st line :
    
    • piperacillin/tazobactam I.V
    • imipenem/cilastin I.V
  • 2nd line:
    
    • ticarcillin/clavulanate I.V
    • ertapenem

Question 14

peritonitis

Answer 14

• Ceftriaxone i.v