Penicillin G, V
Prototype β-lactam antibiotics (penicillinase-sensitive)
Penicillin G, V mechanism
Bind penicillin-binding proteins (transpeptidases). Block transpeptidase cross-linking of peptidoglycan in cell wall. Activate autolytic enzymes.
Penicillin G,V clinical use
Mostly used for gram-positive organisms
Penicilling G, V toxicity
* Hemolytic anemia
Penicillin G, V resistance
Penicillinase in bacteria (a type of β-lactamase) cleaves β-lactam ring.
Aminopenicillins
* ampicllinPenicillinase-sensitive penicillins
Aminopenicillin mechanism
Aminopenicillin clinical use
Exteneded spectrum penicillin
Aminopenicillin toxicity
Aminopenicillin resistance
Penicillinase in bacteria (a type of β-lactamase) cleaves β-lactam ring.
Penicillinase-resistant penicillins
Penicillinase resistant penicillins mechanism
(dicloxacillin, nafcillin, oxacillin)Same as penicillin → narrow spectrum.Penicillinase resistant because bulky R group blocks access of β-lactamase to β-lactam ring.
Penicillinase resistant penicillins clinical use
(dicloxacillin, nafcillin, oxacillin)S. aureus (except MRSA; resistant because of altered penicillin-binding protein target site).
Penicillinase resistant penicillins toxicity
* interstitial nephritis
Antipseudomonals
* Ticarcillin
Antipseudomonal mechanism
(piperacillin, ticarcillin)Same as penicillin. Extended spectrum.
Antipseudomonal clinical use
(piperacillin, ticarcillin)Pseudomonas spp. and other gram-negative rods.Susceptible to penicillinase; use with β-lactamase inhibitors.
Antipseudomonal toxicity
(piperacillin, ticarcillin) Hypersensitivity reactions.
Beta lactamase inhibitors
Cephalosporins (generations 1-4) mechanism
β-lactam drugs that inhibit cell wall synthesis but are less susceptible to penicillinases. Bactericidal.Organisms typically not covered by cephalosporins are LAME:
First generation cephalosporins
* cephalexin (oral)
First generation cephalosporin clinical use
1st generation (cefazolin, cephalexin)—
Second generation cephalosporin clinical use
2nd generation (cefoxitin, cefaclor, cefuroxime)—
Second generation cephalosporins