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RavLect12: Cephs
Cephalosporins
| Term | Definition |
|---|---|
| Cephalosporin MoA | bactericidal cell wall active, inhibit cell wall synthesis leading to abnormal cell wall bind to penicillin binding proteins (PBPs) & essential enzymes required to build cell wall synergistic w/ aminoglycosides (G+/-) additive w/ quinolones |
| Mech of resistance to Cephs | Beta-lactamase including ESBL’s Altered cell wall penetration limiting access to targets PBP affinity alteration |
| Gen SoA of Cephs | From 1st to 4th gen, you start with G+ and do pick up G-. Do NOT work for enterococcus or Listeria! |
| 1st Gen Cephs | cefazolin (Ancef) cephalexin (Keflex)/cephradine cefadroxil |
| 1st Gen Cephs: SoA | Mainly G+ cocci, eg. Staphylococcus and Streptococcus |
| Ancef (cefazolin) | frequently used IV as a pre-operative prophylaxis antibiotic against skin organisms or general penicillin or methicillin susceptible S. aureus |
| Cephs PK | Cleared renally, requiring adjustment Concentration INdependent (all b-lactams are) |
| Ceftriaxone (Rosephin) doses | Gonorrhea: 125-250mg IM x 1 dose (w/ Azith for Chlamydia) Meningitis: 2g BID IV Pneumonia: 1-2g QD |
| 2nd Gen Cephs | cefaclor cefprozil cefuroxime cefoxitin* cefotetan* *most freq used, these are cephamycins |
| 2nd Gen Cephs spectrum | Similar to 1st gen, but more activity against H. influenza, Enterobactericeae, N. gonorrhoeae (don't use for MSSA, use 1st gen Cephs) |
| Cephamycin (Cefotetan, Cefoxitin) SoA | enhanced activity for Enterobacteriaceae (E. Coli, Klebsiella) and anaerobic coverage for B. fragilis. freq used for intra-abdomnial/pelvic infections/prophylaxis |
| Cefotetan ADRs | MTT group in structure causes bleeding risk (not good for ptx with GI ulcers) & ETOH intolerance (not good for alcoholics!). |
| Cefoxitin | Like Cefotetan (same SoA) except no bleeding risk or ETOH problem b/c lack of MTT group. However, less stable (shorter half-life) |
| Cefuroxime | Classic true Ceph in 2nd gen Must be taken with food for absorption! for Strept. pneumonia & H. influenza for upper RT infection |
| 3rd Gen Cephs (Good for penicillin intermediate/resistant Streptococcus pneumoniae & has good H. influenzae coverage thus is frequently used for CAP. Don't use for MSSA) | ceftriaxone cefotaxime ceftazidime cefixime cefpodoxime cefditoren ceftizoxime |
| Ceftriaxone and cefotaxime mainly used for? (hint: NOT pseudomonas) | RT infection: Strept pneumo (even the drug-resistant forms when PBP is altered!) H. influenza Also used for: adult bacterial meningitis gonorrhea |
| Ceftriaxone ADR | biliary stones/sludge (not good for babies or elderly with weak hepatic fxn) Thus, Cefotaxime is better since it has identical SoA, but is cleared by the kidney & therefore, no biliary problems. |
| Ceftazidime is used for meningitis, CAP, RT infection. Problem: may induce ESBL | The only ceph besides Cefepime that covers Pseudomonas Aeruginosa (thus, active for other G- such as H. flu). Also covers S. pneumo. Tests for ESBL. If E. Coli, Klebsiella, or Acinetobacter are resistant to Ceftazidine, then they're ESBL producers. |
| Cefixime | PO. Used in children's RT or ear infections. |
| Which of the cephs are taken with food to increase absorption? | • Cefuroxime • Cefditoren • Cefpodoxime (Vantin) |
| Cefpodoxime | like an oral cefotaxime. Take with food. |
| Cefditoren | Cefpodoxime is preferred b/c it has the same spectrum w/o 3 main issues of Cefditoren: L-carnitine: caution in L-carnitine deficiency since Cefditoren increases its excretion BA prob: needs high-fat meal for absorption Caseinate (milk protein: al |
| 4th Gen Ceph | Cefepime |
| Cefepime | Zwitterionic: rapid outer membrane passage of gram negative organisms for Pseudomonas & S. pneumoniae generally reserved for SPACE & ICU infections |
| 2 cephs for pseudomonas | Ceftazidine Cefepime |
| 2 cephs for IAB infections | Cefoxitin Cefotetan |
| 2 cephs for hospitalized patients with CAP (a bunch will cover RT) or meningitis | Ceftriaxone Cefotaxime |
| Ceftaroline | This is the only ceph that covers MRSA! Better than using Vanco b/c less Side effects It has increased affinity for PBP 2x and 2a for Streptococcus pneumoniae and Staphylococcus aureus (back up for Strept. pneumo if resistant to Ceftriaxone) |
| Ceftaroline | Covers CAP, so Strept Pneumo & H. Influenza, but doesn't cover atypicals such as legionella, chlamydia, & mycoplasma in CAP. |
| How to Tx CAP? | Usually with 2 drugs (Cephs + macrolide or quinolone to manage the atypicals) |
Created by:
cheeoh
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