Cephalosporins 5th generation


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Cephalosporins 5th generation

  1. 1.  Cephalosporins are structurally and pharmacologically related to the penicillins  They have a beta-lactam ring structure that interferes with synthesis of the bacterial cell wall  Bactericidal Activity
  2. 2.  Cephalosporins are bactericidal agents and have the same mode of action as other beta-lactam antibiotics (such as penicillins).  Cephalosporins disrupt the synthesis of the peptidoglycan layer of bacterial cell walls, which causes the walls to break down and eventually the bacteria die.
  3. 3.  Cephalosporins are bactericidal for most of the following:  Gram-positive bacteria  Gram-negative bacteria  Cephalosporins are used to treat infections in different parts of the body—the ears, nose, throat, lungs, sinuses, and skin, for example.  Cephalosporins are a newer class of antibiotics and often are seen as an alternative to penicillin
  4. 4.  Cephalosporins are grouped into "generations" based on their spectrum of antimicrobial activity.  Each newer generation of cephalosporins has significantly greater gram-negative antimicrobial properties than the preceding generation, in most cases with decreased activity against gram-positive organisms.  Fourth generation cephalosporins, however, have true broad spectrum activity.
  5. 5. Currently there are only two drugs in this category, Ceftobiprole and Ceftaroline. These new drugs are also the only β-lactam antibiotics that are effective against methicillin-resistant- Staphylococcus-aureus (MRSA). They inhibits the 2a penicillin-binding protein (PBP) of methicillin- resistant Staphylococcus aureus and the 2x PBP of Streptococcus pneumoniae, as well as the classic PBP-2 of MSSA. Ceftobiprole is resistant to staphylococcal β-lactamase.
  6. 6.  MRSA is any strain of Staphylococcus aureus that has evolved resistance to beta- lactam antibiotics, which include the penicillins (methicillin, dicloxacillin, nafc illin, oxacillin, etc.)  and the cephalosporins. Strains unable to resist these antibiotics are classified as methicillin-sensitive Staphylococcus aureus, or MSSA.  resistance does make MRSA infection more difficult to treat with standard types of antibiotics and thus more dangerous.
  7. 7. Ceftobiprole Ceftobiprole is a pyrrolidinone-3- ylidenemethyl cephem. The C-3 side chain was specifically designed to have a strong binding affinity to PBP2a and PBP2x. PBP2a is known to give staphylococci resistance to other β-lactam drugs and PBPx does the same for pneumococci. Ceftobiprole also has a aminothiazoylhydroxyimino side chain at the C-7 position which is known to give good resistance to β-lactamase from S. aureus. Together these active groups make Ceftobiprole bactericidal to MRSA. Ceftobiprole has poor water solubility and is therefore administered intravenously. Clinical used: Methicillin-resistant Staphylococcus aureus associated with endocarditis and bone and joint infections Pneumonia caused by Penicillin-resistant Streptococcus pneumoniae Pseudomonas aeruginosa Enterococci.
  8. 8. Ceftaroline Ceftaroline was developed from the fourth generation cephalosporin Cefozopran, It retains the alkoxyimino group at position C-7 from earlier generations so it is fairly stable in the presence of many β-lactamases. Since MRSA and penicillin resistant Streptococcus pneumoniae have resistance dedicated to new types of PBP, PBP2a and PBP2x respectively, both Ceftaroline and Ceftobiprole have C-3 side chains specially engineered to bind these new PBP. In the case of Ceftaroline this side chain contains a 2-thioazolythio spacer linkage optimised for its anti-MRSA activity.]