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Microbiology

Terms in this set (70)

MECHANISM: β-lactam drugs that inhibit cell wall synthesis
but are less susceptible to penicillinases. Bactericidal.

Organisms typically not covered by 1st-4th generation cephalosporins are LAME:
Listeria, Atypicals (Chlamydia, Mycoplasma), MRSA, and Enterococci.

CLINICAL USE"
1st generation (cefazolin, cephalexin)—gram ⊕
cocci, Proteus mirabilis, E coli, Klebsiella pneumoniae. Cefazolin used prior to surgery to
prevent S aureus wound infections.
1st generation—PEcK.

2nd generation (cefaclor, cefoxitin, cefuroxime,
cefotetan)—gram ⊕ cocci, H influenzae, Enterobacter aerogenes, Neisseria spp., Serratia
marcescens, Proteus mirabilis, E coli, Klebsiella pneumoniae.
2nd graders wear fake fox fur to tea parties. 2nd generation—HENS PEcK.

3rd generation (ceftriaxone, cefotaxime, cefpodoxime, ceftazidime)—serious gram ⊝
infections resistant to other β-lactams. Can cross blood-brain barrier. Ceftriaxone—meningitis, gonorrhea, disseminated Lyme disease. Ceftazidime—Pseudomonas.

4th generation (cefepime)—gram ⊝ organisms, with activity against Pseudomonas and gram ⊕ organisms.

5th generation (ceftaroline)—broad gram ⊕ and gram ⊝ organism coverage; unlike 1st-4th
generation cephalosporins, ceftaroline covers Listeria, MRSA, and Enterococcus faecalis—
does not cover Pseudomonas.

ADVERSE EFFECTS: Hypersensitivity reactions, autoimmune hemolytic anemia, disulfiram-like reaction,
vitamin K deficiency. Low rate of crossreactivity even in penicillin-allergic patients. increased nephrotoxicity of aminoglycosides.

MECHANISM OF RESISTANCE: Inactivated by cephalosporinases (a type of β-lactamase). Structural change in penicillinbinding
proteins (transpeptidases).