PCN/CPH Flashcards
PO PCN
- Natural PCN (PCN VK)
- Anti-staph PCN (Dicloxacillin)
- AminoPCN (Amoxicillin)
- Augmented AminoPCN (amox/clav)
IV PCN
- Natural PCN (PCN G)
- Anti-staph PCN (Nafcillin)
- AminoPCN (ampicillin)
- Augmented AminoPCN (amp/sulbactam)
- Extended-spectrum PCN (piptaz)
PCN and Cephalosporin MOA
Arrest cell wall synthesis by binding to PBPs
**bacteria need to be actively dividing for B-lactams to work
PCN and Cephalosporin Mechanism of Resistance
- destruction of abx by b-lactamases
- failure of abx to penetrate to PBP targets
- low-affinity binding of abx to PBP
PCN Pharmacology
- minimal drug interactions
- most renal excretion (except Nafcillin)
- time-dependent killing
- bactericidal
coverage:
- natural PCNs & anti-staph PCNs have good G+ activity
- as generations increase you lose G+ and gain G-
PCN ADRs
Class Effect:
- hypersensitivity rxn
- drug fever (rare)
Unique:
- **nafcillin: phlebitis, AIN, hypokalemia
- **clavulanate: diarrhea, hepatotoxicity (subclinical LFT elevations)
Natural PCNs
- PCN G (IV) or PCN VK
- Benzathine PCN (IM)
Common Indications:
- strep pharyngitis* / cellulitis
- various stages of syphilis*
Benzathine IM - think of as long acting IM shot
Anti-Staphylococcal PCNs
- Nafcillin (IV) or dicloxacillin (tab)
Common Indications:
- SSTIs* (esp when S. aureus suspected)
AminoPCNs
- Ampicillin (IV) or amoxicillin
Common Indications:
- URTIs* (pharyngitis, AOM secondary bacterial infection)
- streptococcal skin infections
- endocarditis prophylaxis for dental procedures*
- lyme disease*
Augmented AminoPCN
- amp/sul (IV) or amox/clav
Common Indications:
- animal/human bite prophylaxis or tx*
- amoxicillin failure URTIs (AOM, sinusitis, AE-COPD)*
- recurrent streptococcal pharyngitis
- SSTIs
- dental infections*
How do you prescribe amoxicillin/clavulanate?
Dose is based on amoxicillin component.
Determine appropriate dose and choose correct product (products are not interchangeable)
“Hardest abx to prescribe,” says Paxty
Extended-Spectrum PCNs
- Pip/Taz (IV)
Common Indications:
- mostly nosocomial infections
- “serious outpatient –> inpatient infections (e.g. perforated diverticulum)
PO Cephalosporins
1st gen - cephalexin
2nd gen - cefuroxime
3rd gen - cefpodoxime
IV Cephalosporins
1st gen - cefazolin 2nd gen - cefuroxime 3rd gen - ceftriaxone 4th gen - cefepime 5th gen - ceftaroline
Cephalosporin Pharmacology
- minimal drug interactions
- most renal excretion (least with ceftriaxone)
- time-dependent killing
- bactericidal
Coverage:
- 1st/2nd gen: good G+
- increase generations generally lose G+ and gain G- (except 5th gen)
- no cephalosporin covers Enterococci or Listeria*
Cephalosporin ADRs
Class effect
- hypersensitivity rxn
- drug fever (rare)
Unique effects
- serum-sickness like rxn common w/cefaclor
- ceftriaxone & neonates* –> precipitates w/Ca2+ –> pseudocholelithiasis (precipitates in baby’s lungs)
1st Gen Cephalosporin
- cefazolin (IV) or cephalexin
Common Indications:
- SSTIs*
- Streptococcal pharyngitis
- Lower UTI (cystitis) - good in pregnancy*
- perioperative prophylaxis (cefazolin)*
2nd Gen (Respiratory*) Cephalosporins
- cefuroxime (tab, IV)
Common indications
- amoxicillin failure URTIs (AOM, sinusitis, AE-COPD)*
- SSTIs
3rd Gen Cephalosporin - PO
- cefpodoxime, cefdinir
Common Indications:
- essentially the same as cefuroxime
3rd Gen Cephalosporin - PAR
- ceftriaxone (IM, IV)
Common Indications:
- refractory AOM
- CAP (w/azithromycin)*
- meningitis*
- gonorrhea*
- intraabdominal infection (e.g. pyelonephritis, diverticulitis)*
- serious lyme disease (heart, CNS)
4th Gen Cephalosporins
- cefepime (IV)
Common Indications
- mostly nosocomial infections
5th Gen Cephalosporins
- ceftaroline (IV)
strong affinity for PBP2a (modified PBP in MRSA) & PBP2x (modified PBP in PCN-resistant S. pneumoniae) –> 1st cephalosporin with any MRSA activity*
doesn’t have extended GNB coverage that you might expect from higher-generation cephalosporin*
Natural PCN Coverage
PCN G (IV) or PCN VK Benzathine (IM)
- S. pyogenes (GAS) & T. pallidum
Anti-Staphylococcal PCN Coverage
Nafcillin (IV) or dicloxacillin (tab)
- S. aureus (MRSA) & S. pyogenes (GAS)
AminoPCNs Coverage
Ampicillin (IV) or amoxicillin
- S. pyogenes
- S. pneumoniae
- S. galactiae (GBS)
- Enterococci
- B. burgdorferi
- P. multocida
- Proteus
- Listeria
Some: H. influenzae, E. coli
Augmented AminoPCN Coverage
Amp/Sul (IV) or Amox/Clav
Same as AminoPCN PLUS - M. catarrhalis - H. influenzae - Most anaerobes Some: E. coli, Klebsiella
Extended Spectrum PCN Coverage
Pip/Taz (IV)
GPC:
- S. pyogenes
- S. pneumoniae
- S. agalactiae (GBS)
- Enterococci
GNB:
- M. catarrhalis
- H. influenzae
- Proteus
- E. coli
- Klebsiella
- Enterobacter
- Serratia
- Pseudomonas ** - only anti-pseudomonal PCN
Most anaerobes
“Thou shall not use Zosyn every time”
1st Gen Ceph Coverage
Cefazolin (IV) or cephalexin
- S. pyogenes (GAS)
- S. aureus (MSSA)
Some: E. coli, Klebsiella, Proteus
2nd Gen Ceph Coverage
Cefuroxime (tab, IV)
Same as 1st gen PLUS
- S. pneumoniae
- M. catarrhalis
- H. influenzae
- Pasteurella
“Similar to augmentin-ish”
3rd Gen Ceph PO Coverage
Cefpodoxime & Cefdinir
Similar coverage as cefuroxime BUT more GNB acitivity…but cefuroxime is no longer suspension*
3rd Gen Ceph PAR Coverage
Ceftriaxone (IV, IM)
“wimpy” GNB
- E. coli
- Klebsiella
- Proteus
- M. catarrhalis
- H. influenzae
Some GPC
- S. pneumoniae
- most other “strep”
4th Gen Ceph Coverage
Cefepime (IV)
“Resistant” GNB
- Pseudomonas
- Enterobacter
- Serratia
- S. pneumoniae
5th Gen Ceph Coverage
Ceftaroline (IV)
“Ceftriaxone with MRSA activity”
** only B-lactam that kills MRSA
