Sunday, 3 February 2013

Antibiotic classification

An antibiotic is an agent that either kills or inhibits the growth of a microorganism. This useful infographic outlines some of the major categories of antibiotics available to healthcare practitioners.

Antibiotic classification chart

The successful outcome of antimicrobial therapy with antibacterial compounds depends on several factors. These include host defense mechanisms, the location of infection, and the pharmacokinetic and pharmacodynamic properties of the antibacterial. A bactericidal activity of antibacterials may depend on the bacterial growth phase, and it often requires ongoing metabolic activity and division of bacterial cells.

Antibacterial antibiotics
are commonly classified based on their mechanism of action, chemical structure, or spectrum of activity. Most target bacterial functions or growth processes. Those that target the bacterial cell wall (penicillins and cephalosporins) or the cell membrane (polymyxins), or interfere with essential bacterial enzymes (rifamycins, lipiarmycins, quinolones, and sulfonamides) have bactericidal activities. Those that target protein synthesis (macrolides,lincosamides and tetracyclines) are usually

bacteriostatic (with the exception of bactericidal aminoglycosides).

Classification of antibiotics on the basis of chemical structure:

  1. Carbohydrate containing Antibiotics:
  2. Pure saccharides antibiotics: examples; Streptozotocin
  3. Aminoglycosides: examples; Streptomycin
  4. N/O glycosides: eg. Chromomycin
  5. Other: eg; Lincomycin
  6. Macrocyclic lactone antibiotics: eg. Erythromycin
  7. Quinolones antibiotics; eg. Fluroquinolone
  8. N-containing heterocyclic antibiotics: eg. Beta-lactum
  9. O-containing heterocyclic antibiotics: eg. Cycloserine
  10. Alicyclic antibiotics: eg. Cycloheximide
  11. Aromatic antibiotics (Nitrobenzene): eg. Chloramphenicol
  12. Aliphatic amine antibiotics: eg. Spermidine
  13. Peptide antibiotics: eg. Polymyxin, Bacitracin, Gramicidin
Classification of antibiotics on the basis of origin:

Microbial origin:

  • Bacillus polymyxa: Polymyxin
  • Chromobacter violaceum: Bacitracin
  • Micromonospora spp: Gentamycin
  • Penicillium notatum: Penicillin
  • Cephalosporin spp: Cephalosporin
  • Streptomyces griseus: Streptomycin
  • S. venezuelue: Chloramphenicol
  • S. erythreus: Erythromycin
  • S. mediterranae: Rifampicin

Further categorization is based on their target specificity. "Narrow-spectrum" antibacterial antibiotics target specific types of bacteria, such as Gram-negative or Gram-positive bacteria, whereas broad-spectrum antibiotics affect a wide range of bacteria. Following a 40-year hiatus in discovering new classes of antibacterial compounds, four new classes of antibacterial antibiotics have been brought into clinical use: cyclic lipopeptides (such as daptomycin), glycylcyclines (such as tigecycline), oxazolidinones (such aslinezolid), and lipiarmycins (such as fidaxomicin).

READ MORE: Controlling antimicrobial resistance

 Posted by Tim Sandle, for Pharmaceutical Microbiology

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