Cephalosporin
|
|
The cephalosporins, are a class of ß-lactam antibiotics. Together with cephamycins they belong to a sub-group called cephems.
| Contents |
History
Cephalosporin was first isolated from cultures of Cephalosporium acremonium from a sewer in Sardinia in 1948 by an italian scientist Giuseppe Brotzu. He noticed that these cultures produced a substance that was effective against salmonella typhi, the cause of typhoid. In 1960s, Eli Lilly launched the first cephalosporins on the market.
Mode of action
Cephalosporins work the same way as penicillins, they interfere with the peptidoglycan synthesis of the bacterial wall by inhibiting the final transpeptidation needed for the cross-links. This effect is bacteristatic.
Cephalosporin_nucleus.png
The generations
The cephalosporin nucleus can be modified to gain different properties.
First generation cephalosporins
First generation cephalosporins have a spectrum of activity that includes penicillinase-producing, methicillin-susceptible staphylococci and streptococci, though they are not the drugs of choice for such infections. They also have activity against some Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis, but have no activity against Bacteroides fragilis, enterococci, methicilllin-resistant staphylococci, Pseudomonas, Acinetobacter, Enterobacter, indole-positive Proteus or Serratia.
- cephazolin (cefazolin)
- cephalothin
- cephapirin
- cephalexin
- cephradine
- cephadroxil
- cephaclor
Second generation cephalosporins
The second generation cephalosporins have a greater gram-negative spectrum while retaining some activity against gram-positive cocci. They are also more resistant to beta-lactamase.
- cefamandole
- cefuroxime
- cefonicid
- ceforanid
- cefaclor
- cefixime
- cefprozil
- cefpodoxime
- loracarbef
- cefotetan
Third generation cephalosporins
Third generation cephalosporins have a broad spectrum of activity against enteric gram-negative rods and thus are particularly useful in treating hospital-acquired infections.
- ceftriaxone
- cefotaxime
- ceftizoxime
- ceftazidime
- cefoperazone
- cefsulodin
- ceftibuten
- cefixime
- cefatamet
Fourth generation cephalosporins
Fourth generation cephalosporins have a greater spectrum of activity against gram-positive organisms than the third generation cephalosporins. They also have a greater resistance to beta-lactamases than the third generation cephalosporins.