Antibiotics

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Penicillin


Cephalosporins


Mnemonic

Cephalosporins are LAME: 1st–4th generation cephalosporins do not act against

  • Listeria
  • Atypical organisms (e.g., Chlamydia, Mycoplasma)
    • No cell wall
  • MRSA
  • Enterococci (with the exception of ceftaroline, which does act against MRSA).

Nitrofurans

Drug resistance


Mechanisms

Type of resistance Example mechanisms Example antibiotics affected
Increased drug efflux pump • New membrane transport system • Tetracyclines, fluoroquinolones
Drug-inactivating enzyme • Beta-lactamase
• Acetyltransferase
• Penicillins, cephalosporins
• Aminoglycosides
Decreased drug uptake • Mutated porin protein • Penicillins, fluoroquinolones
Modified drug target • Altered penicillin-binding protein
• Altered ribosomal protein
• Altered DNA gyrase
• Penicillins
• Aminoglycosides, macrolides
• Fluoroquinolones

Examples

1. MRSA (Methicillin-Resistant Staphylococcus aureus)

2. VRE (Vancomycin-Resistant Enterococci)

3. Extended-Spectrum Beta-Lactamase (ESBL)-Producing Enterobacterales (E. coli, Klebsiella)

4. CRE (Carbapenem-Resistant Enterobacterales - e.g., Klebsiella pneumoniae carbapenemase/KPC)

5. Drug-Resistant Streptococcus pneumoniae

6. MDR-TB & XDR-TB (Multidrug/Extensively Drug-Resistant Tuberculosis)