dr. bawoh. m
DESCRIPTION
Lecture for med. studentsTRANSCRIPT
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β- lactams: cell wall inhibitors
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β-lactam ring
•The β-lactam ring is a common structure for:•Penicillins•Cephalosporins•Monobactams•Carbapenems
• Bacteria will target this ring to gain resistance.
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Cell wall inhibitors: important features
• Cell wall inhibitors have bacericidal effect.
• They act sinergistically with amynoglycosides
• Time-dependent kinetics: the more time the drug binds the bacteria, the more effective it is.
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Mechanism of action 1
•Some PBP have transpeptidase activity.• Transpeptidase activity is essential in cell wall synthesis.
•Beta-lactams bind PBP (Penicillin Binding Proteins).
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Mechanism of action 2
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Cephalosporins
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Cephalosporins: characteristics
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Chemical structure of cephalosporins
• Derived from 7-aminocephalosporanic acid.
• They suffer the “attack” of bacteria at their beta-lactam ring.
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First gen. cephalosporins.:
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1st Generation cephalosporins: antibacterial coverage
Active mainly against Gram positive cocci. Less active against Gram negative.
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Clinical uses of first gen. cephalosporins
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2nd generation cephalosporins
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2nd generation cephalosporins. Antibiotic coverage
Increased coverage against Gram negatives, while keeping coverage against Gram +.
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3rd generation cephalosporins
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3rd generation cephalosporinsCoverage
Increased coverage against Gram negatives.Decreased coverage against Gram +
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3rd generation cephalosporinsClinical uses
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Ceftriaxone and meningitis
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4th generation cephalosporins
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4th generation cephalosporinsAntibacterial coverage
Coverage against Gram + and Gram -, good activity against β-lactamase producing bacteria.