deck_3522262 Flashcards
Penicillin G, V
Prototype β-lactam antibiotics (penicillinase-sensitive)
- Penicilling G → Iv and IM form
- Penicillin V → oral
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
- S. pneumoniae
- S. pyogenes
- Actinomyces Gram negative cocci
- N. meningitidis Spirochetes
- T. pallidum Bactericidal for gram-positive cocci, gram-positive rods, gram-negative cocci, and spirochetes.Penicillinase sensitive.
Penicilling G, V toxicity
- Hypersensitivity reactions
* Hemolytic anemia
Penicillin G, V resistance
Penicillinase in bacteria (a type of β-lactamase) cleaves β-lactam ring.
Aminopenicillins
- amoxicillin
* ampicllinPenicillinase-sensitive penicillins
Aminopenicillin mechanism
- Same as penicillin → wider spectrum,
- Penicillinase sensitive.
- Also combine with clavulanic acid to protect against destruction by β-lactamase.(amoxicillin and ampicillin)Note that amoxicillin has greater oral bioavailability than ampicllin.
Aminopenicillin clinical use
Exteneded spectrum penicillin
- H. influenzae (gram negative)
- H. pylori (gram negative, oxidase positive, comma shaped)
- E. coli (gram negative rod)
- Listeria monocytogenes (gram positive rod)
- Proteus mirabilis (gram negative rod)
- Salmonella (gram negative rod)
- Shigella (gram negative rod)
- enterococci(gram positive cocci)
Aminopenicillin toxicity
- hypersensitivity reactions
- rash
- pseudomembranous colitis (ie C. dif, a gram positive rod)
Aminopenicillin resistance
Penicillinase in bacteria (a type of β-lactamase) cleaves β-lactam ring.
Penicillinase-resistant penicillins
- Dicloxacillin
- Nafcillin
- Oxacillin
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
- Hypersensitivity reactions
* interstitial nephritis
Antipseudomonals
- Piperacillin
* 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
- Clavulanic Acid
- Sulbactam
- TazobactamOften added to penicillin antibiotics to protect the antibiotic from destruction by β-lactamase (penicillinase).
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:
- Listeria
- Atypicals (Chlamydia, Mycoplasma)
- MRSA
- EnterococciException: ceftaroline covers MRSA.
First generation cephalosporins
- Cefazolin (IV)
* cephalexin (oral)
First generation cephalosporin clinical use
1st generation (cefazolin, cephalexin)—
- gram-positive cocci gram-negative rods
- Proteus mirabilis
- E. coli
- Klebsiella pneumoniae Cefazolin used prior to surgery to prevent S. aureus wound infections.
Second generation cephalosporin clinical use
2nd generation (cefoxitin, cefaclor, cefuroxime)—
- gram-positive cocci
- Haemophilus influenzae
- Enterobacter aerogenes
- Neisseria spp.
- Proteus mirabilis
- E. coli
- Klebsiella pneumoniae
- Serratia marcescens
Second generation cephalosporins
- cefoxitin (IV)
- cefaclor
- cefuroxime