Penicillins (FETT)

Antibacterials

BENZYLPENICILLIN

AMOXICILLIN

FLUCLOXACILLIN

Co-amoxiclav

Piperacillin with tazobactam

• Penicillin G (benzylpenicillin)

  • IV: crystalline penicillin G

  • IM: procaine penicillin G, benzathine penicillin G

• Oral: penicillin V (phenoxymethylpenicillin)

• Gram-positive aerobes (esp. Streptococcus pyogenes, Streptococcus pneumoniae)

• Gram-negative cocci (esp. Neisseria meningitidis)

• Spirochetes (esp. Treponema pallidum)

• Branching gram-positive anaerobes (especially Actinomyces)

• Hypersensitivity reactions

• Hemolytic anemia positive direct Coombs test

• Drug-induced interstitial nephritis

• Seizures

• Cleavage of the β-lactam ring by β-lactamases (penicillinases)

• PBP mutations

• Nafcillin

• Dicloxacillin

• Oxacillin

• Floxacillin

• Methicillin

intrinsically β-lactamase resistant through the addition of bulky side chains (e.g., isoxazolyl), which prevent bacterial β-lactamase from hydrolyzing the β-lactam ring

narrow spectrum

• Gram-positive aerobes, especially S. aureus (non-MRSA)

• Penicillinase-resistant penicillins are not effective against Streptococcus viridans, Enterococci, or Listeria.

• Interstitial nephritis (esp. associated with methicillin use)

• Hypersensitivity reactions

alteration of PBP binding site → reduced affinity → pathogen is not bound or inactivated by β-lactam (an altered PBP target site is one of the main virulence factors of MRSA)

• Oral or IV: amoxicillin (combined with clavulanate )

• IV or IM: ampicillin (with or without sulbactam)

• The molecular structure is similar to penicillin and therefore susceptible to degradation by β-lactamase (β-lactamase sensitive).

• Oral bioavailability of amoxicillin is greater than that of ampicillin

broader spectrum of activity than penicillin (extended-spectrum penicillin)

• Gram-positive aerobes

• Gram-negative rods (not effective against Enterobacter spp.)

• Most effective against:

  • H. pylori

  • H. influenzae

  • E. coli

  • Listeria monocytogenes

  • Proteus mirabilis

  • Salmonella

  • Shigella

  • Enterococci

  • Spirochetes

• Diarrhea

• Pseudomembranous colitis

• Hypersensitivity reactions

• Drug-induced rash

• Possibly acute interstitial nephritis

cleavage of the β-lactam ring by penicillinases

• IV ureidopenicillins: piperacillin (combined with tazobactam) , mezlocillin

• IV carboxypenicillins (e.g., ticarcillin)

• PO carbenicillin

extended spectrum but penicillinase-sensitive

• Gram-negative rods, especially Pseudomonas

• Also effective against anaerobes (e.g., Bacteroides fragilis)

• Gram-positive aerobes: not effective against S. viridans

hypersensitivity reactions