Cell Wall Synthesis Inhibitors

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  1. Fosfomycin (Monurol)
    • Non-β-lactam drug
    • structural analog of PEP, blocks step-1 PG synthesis
    • pharmacokinetics: well absorbed and distributed, excreted unchanged in urine
    • Broad spectrum
    • resistance emerges from multiple doses
    • toxicity: few, diarrhea and vaginitis
    • use: single dose oral treatment of uncomplicated UTIs caused by susceptible E faecalis and E. coli
  2. D-cycloserine
    • Non-β-lactam drug
    • structural analog of D-alanine, blocks 2 steps of PG synthesis
    • pharmacokinetics: oral, good CNS penetration, active form in urine
    • Broad spectrum
    • toxicity: serious CNS effects - dose related; reversible
    • use: restricted second-line M tuberculosis drug
  3. Bacitracin
    • Non-β-lactam drug
    • mechanism: depletes lipid carrier for PG synthesis
    • pharmacokinetics: topical application only, poorly absorbed
    • narrow spectrum (gram+, Neisseria, T. pallidum)
    • Toxicity: severe nephrotoxicity
    • use: skin and ophthalmologic infections, good in combination with polymyxin B (membrane inhibitor)
  4. Vancomycin (Vancocin)
    • Non-β-lactam drug
    • Structure: glycopeptide; teicoplanin and dalbavancin
    • mechanism: blocks cross-linking of PG synthesis by binding the substrate (binds D-ala - D-ala terminus of pentapeptide); rapidly bactericidal for dividing bacterial cultures (static in enterococci)
    • pharmacokinetics: IV admin (SLOW), not IM; rarely oral - poor absorption; excellent distribution to bone and CNS
    • narrow spectrum (gram + and most MRSA)
    • resistance: 1. VRE - Enterococci vanA, vanB, or vanC genes; different cell wall subunits with reduced binding to vancomycin. 2. VRSA - overexpression of D-ala - D-ala acts as competitor, binds up drug
    • Adverse effects: Red Man Syndrome, ototoxicity and nephrotoxicity
    • use: reserved for serious gram+ infections resistant to other less toxic drugs, MRSA, penicillin-resistant S. pneumonia, synergistic combination with aminoglycosides
  5. Penicillin G
    • β-lactam drug
    • acid-labile - parenteral admin (usually IM, serious infections IV)
    • 2 repository forms for IM injection
    • - procaine and benzathine Pen G
    • - water-insoluble, slow release into bloodstream
    • spectrum: Gram+ and some Gram- cocci
    • Adverse effects: allergies, dose-dependent neurotoxicity and seizures, Stevens-Johnson syndrome
    • use (non-penicillinase producing microbes): S. pneumoniae, Staph. sp., N. meningitidis, Clostridium sp., Treponema pallidum
  6. Penicillin V
    • β-lactam
    • acid stable - oral administration, 60% absorption
    • spectrum: Gram+ and some Gram- cocci
    • Adverse effects: allergies, Stevens-Johnson syndrome
    • use (non-penicillinase producing microbes): S. pneumoniae, Staph. sp., N. meningitidis, Clostridium sp., Treponema pallidum
  7. dicloxacillin and nafcillin
    • β-lactam
    • penicillinase-resistant penicillin
    • pharmacokinetics: acid stable (nafcillin less), food interferes with absorption, can be given parenterally
    • spectrum / use: penicillinase-producing staphylococci and streptococci
    • resistance: MRSA (to methicillin), and PBP with lower affinity for drugs
    • adverse effects: more than Pen G and Pen V; oxacillin: hepatitis at high doses
  8. amoxicillin
    • extended-spectrum penicillin - aminopenicillin
    • Destroyed by β-lactamases
    • pharmacokinetics: acid stable, oral admin
    • spectrum / use: non-lactamase Gram- bacilli (E. coli, H. influenza, Salmonella, Shigella)
    • - not substitute for Pen G and V
    • - for mixed infections
    • - prophylaxis for bacterial endocarditis
  9. carbenicillin
    • extended-spectrum penicillin - carboxypenicillin
    • Destroyed by β-lactamases
    • Retain Gram+ activity, enhanced Gram- activity
    • - Pseudomonas, Klebsiella sp.
    • Parenteral admin
    • Often reserved for serious systemic infections caused by Pseudomonas or Klebsiella
    • - HIV or burn pts
    • - often combined with aminoglycoside
  10. piperacillin
    • extended-spectrum penicillin - ureidopenicillin
    • Destroyed by β-lactamases
    • Retain Gram+ activity, enhanced Gram- activity
    • - Pseudomonas, Klebsiella sp.
    • Parenteral admin
    • Often reserved for serious systemic infections caused by Pseudomonas or Klebsiella
    • - HIV or burn pts
    • - often combined with aminoglycoside
  11. Clavulanic acid
    • β-lactamase inhibitor
    • lacks antibiotic activity alone
    • mechanism: structurally-related to penicillins, β-lactamase suicide inhibitors
    • used in fixed [c] with extended spectrum penicillins (synergistic)
  12. tazobactam and sulbactam
    • β-lactamase inhibitor
    • lacks antibiotic activity alone
    • mechanism: structurally-related to penicillins, β-lactamase suicide inhibitors
    • used in fixed [c] with extended spectrum penicillins (synergistic)
  13. cephalexin (1st gen)
    • cephalosporin
    • pharmacokinetics: Acid stabile, mainly renal excretion, minimal metabolism, given orally, IV or IM, variable distribution
    • resistance: can induce Amp C (cephalosporinase), low affinity PBPs
    • adverse effects: very safe, hypersensitivity (5% pts), cross allergenic with Pens
    • Broadest spectrum against Gram+ cocci (surgical prophylaxis); effective against Gram- bacilli
  14. cefoxitin (2nd gen)
    • cephalosporin
    • pharmacokinetics: Acid stabile, mainly renal excretion, minimal metabolism, given orally, IV or IM, variable distribution
    • resistance: can induce Amp C (cephalosporinase), low affinity PBPs
    • adverse effects: very safe, hypersensitivity (5% pts), cross allergenic with Pens, disulfiram-like rxn (antabuse effect)
    • Only group with significant activity against anaerobes
  15. ceftriaxone (3rd gen)
    • cephalosporin
    • pharmacokinetics: Acid stabile, mainly renal excretion, minimal metabolism, given orally, IV or IM, variable distribution
    • resistance: can induce Amp C (cephalosporinase), low affinity PBPs
    • adverse effects: very safe, hypersensitivity (5% pts), cross allergenic with Pens, disulfiram-like rxn (antabuse effect)
    • Anti-pseudomonal and pneumococcal; serious Gram- infections such as meningitis, pneumonia, gonorrhea
    • Most widely used treatment in children and infants with moderate to severe infections
  16. cefepime (4th gen)
    • cephalosporin
    • pharmacokinetics: Acid stabile, mainly renal excretion, minimal metabolism, given orally, IV or IM, variable distribution
    • resistance: can induce Amp C (cephalosporinase), low affinity PBPs
    • adverse effects: very safe, hypersensitivity (5% pts), cross allergenic with Pens
    • Anti-pseudomonal
    • High resistance to β-lactamases; useful for treating Enterobacter and penicillin-resistant strep
  17. Imipenem
    • carbapenem - β-lactam ring, same mechanism as pens / cephs
    • activity and spectrum: binds more efficiently to PBPs than pens/cephs; penetrates outer membrane of G- bacteria; broadest activity of all β-lactam drugs
    • - NOT for MRSA or VRE
    • - resistant to degradation by most β-lactamases, but induce those that inactivate pens and cephs (antagonize cidal effects of pens and cephs)
    • resistance: alteration of PBPs
    • pharmacokinetics: parenteral admin; renal metabolism and inactivation (administered with cilastatin, inhibits dehydropeptidases)
    • Adverse effects: cross-allergic rxn to penicillin (~5%); rare - GI effects, superinfections, neurotoxicity
    • use: 2nd line therapy for serious nosocomial infections
  18. aztreonam
    • monobactam
    • mechanism: binds PBPs, relatively resistant to β-lactamases
    • pharmacokinetics: IM or IV, drug penetrates inflamed CNS
    • NO significant cross-reactivity with pens
    • spectrum: narrow - limited to G- aerobes (pseudomonas)
    • use: G- UTI, lower RTIs, systemic infections

Card Set Information

Author:
jboi
ID:
322604
Filename:
Cell Wall Synthesis Inhibitors
Updated:
2016-08-24 03:10:06
Tags:
Anitbiotics MOHD
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Description:
MOHD4 lecture 14
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