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Chapter 20

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Penicillins

Bactericidal: Inhibit bacterial cell wall synthesis via competitive inhibition of transpeptidase

Class

Examples

Antimicrobial Spectrum

Adverse Effects

Miscellaneous

Narrow spectrum (β-lactamase susceptible)

  • Penicillin G (IV)
  • Benzathine penicillin G (IM)
  • Procaine penicillin G (IM)
  • Penicillin V (PO)
  • Streptococcus Group A, B, viridans
  • Most Streptococcus pneumoniae
  • Treponema pallidum
  • Neisseria meningitidis
  • Actinomyces spp.
  • Pasteurella multocida
  • Some anaerobes
  • Anaphylaxis
  • Rash
  • Drug fever
  • Bone marrow suppression
  • Hemolytic anemia
  • Interstitial nephritis
  • Renal impairment
  • Penicillin V is acid stable in the stomach
  • Resistance caused by degradation of antibiotic by bacterial penicillinases

Aminopenicillins

  • Ampicillin (IV, IM, PO)
  • Amoxicillin (PO)
  • Streptococcus Group A, B, viridans
  • S. pneumoniae
  • Enterococcus spp.
  • Listeria monocytogenes
  • Haemophilus influenzae if β-lactamase negative
  • Kingella kingae
  • Some gram- negative organisms: Escherichia coli, Salmonella spp., Shigella spp., Proteus spp.
  • GI disturbance
  • Elevated LFTs
  • Bone marrow suppression
  • Hemolytic anemia
  • Allergic reaction
  • Renal impairment
  • Better PO with amoxicillin than ampicillin

β-Lactamase resistant (antistaphylococcal penicillins)

  • Nafcillin (IV)
  • Oxacillin (IV)
  • Dicloxacillin (PO)
  • S. aureus (MSSA)
  • Streptococcus Group A, B, viridans
  • S. pneumoniae
  • Interstitial nephritis
  • Renal impairment
  • Hepatic toxicity
  • Bone marrow suppression
  • Allergic reaction
  • No activity against gram-negative organisms
  • Nafcillin causes more phlebitis than oxacillin (decreased with slow infusion, large-gauge IV)

Antipseudomonal penicillins

  • Piperacillin (IV)
  • Ticarcillin (IV)
  • Carbenicillin (PO)
  • Pseudomonas aeruginosa
  • Streptococcus Group A, B, viridans
  • S. pneumoniae
  • Enterococcus spp.
  • Some gram-negative → Escherichia coli, Enterobacter spp., Salmonella spp., Shigella spp., Proteus spp., Citrobacter spp., Haemophilus spp.
  • Neisseria spp.
  • Platelet dysfunction
  • High Na load
  • Hypokalemia
  • Serum sickness
  • Bone marrow suppression
  • Renal impairment
  • S. viridans and Enterococci are only 30%-60% susceptible

Penicillin + β-lactamase inhibitor

  • Amoxicillin + clavulanate (PO)
  • Ticarcillin + clavulanate (IV)
  • Ampicillin + sulbactam (IV)
  • Piperacillin + tazobactam (IV)
  • Streptococcus Group A, B, viridans
  • S. pneumoniae
  • Enterococcus spp.
  • S. aureus (MSSA)
  • Gram-negative organisms: E. coli, Klebsiella spp., Salmonella spp., Shigella spp., Proteus spp., Aeromonas spp., Pasteurella multocida
  • P. aeruginosa (piperacillin/tazobactam and ticarcillin/ clavulanate)
  • Anaerobes
  • GI disturbance
  • Diarrhea (especially amoxicillin/clavulanate)
  • Rash
  • Renal impairment
  • S. viridans and Enterococci are only 30%–60% susceptible to ticarcillin/clavulanate and piperacillin/tazobactam
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Bactericidal: Inhibit bacterial cell wall synthesis via competitive inhibition of transpeptidase; more resistant to β-lactamases; ∼10% of patients with a severe allergic reaction to penicillin have allergic reactions to cephalosporins

Class

Examples

Antimicrobial Spectrum

Adverse Effects

Miscellaneous

First generation

  • Cefazolin (IV)
  • Cephradine (IV, PO)
  • Cephalexin (PO)
  • Cefadroxil (PO)
  • Cephapirin (IV)
  • Streptococcus Group A, B, viridans
  • S. pneumoniae
  • S. aureus (MSSA)
  • Some gramnegative organisms: M. catarrhalis, H. influenzae, E. coli, Klebsiella spp., Proteus spp.
  • Anaphylaxis
  • Rash
  • Delayed rash
  • Drug fever
  • Bone marrow suppression
  • Renal impairment
  • Minimal CSF penetration
  • Renal excretion
  • Cephalosporins have no activity against Enterococcus spp.

Second Generation

  • Cefamandole (IV, IM)
  • Cefuroxime (IV, PO)
  • Cefonicid (IV)
  • Cefaclor (PO)
  • Cefprozil (PO)
  • Cefotetan (IV)
  • Cefoxitin (IV, IM)
  • Streptococcus Group A, B, viridans
  • S. pneumoniae
  • S. aureus (MSSA)
  • Some gram-negative organisms: M. catarrhalis, H. influenzae, E. coli, Klebsiella spp., Proteus ...

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