Beta-lactam antibiotics: Penicillin, Cephalosporin, Monobactam, Carbapenems and Clavulanic acid




Beta-lactam antibiotics: Penicillin, Cephalosporin, Monobactam, Carbapenems and Clavulanic acid

  • β-lactam antibiotics have common b-lactam ring in their structure. Different b lactam antibiotics differ in their side chain.

There are several types of B-lactam antibiotics which are potentially important.

Some of them are:

  1. Penicillin- penicillin G, methicillin, amphicillin, amoxicillin, carbenicillin, piperacillin, penicillin V
  2. Cephalosporin
  3. Monobactam
  4. Carbapenems
  5. Clavamas-clavulanic acid

1. Penicillin

2. Cephalosporin

3. Monobactams:

  • The most common example of monobactam is Aztreonam. Monobactam are active against β-lactamase producing Gram –ve Enteric bacteria, Pseudomonas and Serratia. They have extended gram –ve coverage than penicillin. However they are inactive gram +ve bacteria and anaerobes.
  • Individuals who are allergic to penicillin are usually not allergic to monobactams
  • Monobactams binds to Penicillin binding protein (PBP) and inhibits transpeptidase activity causing filamentation of bacteria which dies later.

list of monobactam antibiotics

  • Azteronam
  • Tigemonam
  • carumonam
  • Nocardicin A

4. Carbapenems:

  • Carbapenems are broad spectrum drug, virtually active against every bacteria. They are active against Gram +ve and Gram –ve bacteria including Pseudomonas, Serratia, indole positive Proteus and Bacteroid fragellis. Carbapenems are resistant to hydrolysis by β-lactamases.

Example ofcarbapenems:

  • Thienamycin
  • Imipenem
  • Mezopenem
  • Ertapenem
  • Imipenem can be hydrolysed by dihydropeptidase found in renal tubules in Human, so imipenem should be administered along with dihydropeptidase inhibitors (Cilastatin).
  • Meropenem and ertapenem are resiatant to hydrolyse by dihydroxypeptidase.
  • Individuals allergic to penicillin should not be recommended Carbapenem drugs.
  • Bacteria producing metallo-β-lactamase such as Stenotrophomonas metophila and Bacteroids fragillis are resistant to carbapenems.

5. Clavulanic acid:

  • Clavulanic acid is a β-lactamase inhibitors. The resistant strain of bacteria producing βlactamase enzyme hydrolyse β-lactam antibiotics and become resistant.
  • β-lactamase inhibitors have special property of inhibiting activity of β-lactamase. They are also β-lactam group of antibiotics with very litte antimicrobial activity.
  • The β-lactamase inhibitors are used in combination with β-lactam antibiotics.

Beta-lactam antibiotics: Penicillin, Cephalosporin, Monobactam, Carbapenems and Clavulanic acid

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