Mechanism
of Action of Penicillins: β-Lactam
antibiotics,Bactericidal.
1. The Penicillin interferes with
the last steps of bacterial cell wall synthesis by inhabiting transpeptidation
enzyme which required for Peptidoglycan synthesis. it acts by a receptors name Penicillin
Binding Proteins(PBPs).
2. Penicillin
inactivates the inhibitors of autolytic enzymes in the bacterial cell wall.
Mechanism
of Action of Cephalosporins: β-Lactam
antibiotics, Bactericidal
1. As
like Penicillin, Cephalosporin also interferes with bacterial cell wall
synthesis by inhabiting transpeptidation enzyme which required for
Peptidoglycan synthesis. It acts by a receptors name Penicillin Binding
Proteins (PBPs).
Mechanism of Action of Vancomycin: Bactericidal
1. As
like Penicillin,Vancomycin also inhabit bacterial cell wall synthesis by
preventing peptydoglycan elongation and cross linking.
Mechanism
of Action of Tetracyclin: Having four partially unsaturated
cyclo-hexane radicals on its nephthacene nucleus, Bacteriostatic
1. Its
reversibly binds with 30S subunit of bacterial ribosome and blocking the
binding the Aminoacyl-tRNA to the acceptor site on the mRNA-ribosome complex.
Thus inhabits bacterial protein synthesis.
Mechanism
of Action of Aminoglycosides: contain two or more aminosuger linked
to an aminocyclital ring by glycosidic bond. Bactericidal
1. Its
binds with 30S subunit of bacterial ribosome and interference with initiation
complex of peptide formation, causing misreading of mRNA which results in
incorrect amino acid incorporation. So promotion of polysomal dissociation into
nonfunctional monosome. Thus inhabits bacterial protein synthesis.
Mechanism
of Action of Macrolide: Bactericidal + Bacteriostatic
1. Its
binds with 50S subunit of bacterial ribosome and block movement of peptidyl tRNA from acceptor
to donor site,as a result the next incoming tRNA can not bind to the still occupied acceptor
site. Thus inhabits bacterial protein synthesis.
Mechanism
of Action of Chloramphenicol: Bacteriostatic
1. It’s
reversibly binds with 50S subunit of bacterial ribosome and inhabits
transpeptidation reaction by inhibition of ribosomal peptidyle transferase. So
elongation of protein chain blocks. Thus inhabits bacterial protein synthesis.
Mechanism
of action of Fluroquinolones: Bactericidal
1. It
inhibits DNA gyrase (topoisomerase ll and topoisomerase lV that inhibit the
helical twist in DNA) and interfere with the supercoiling of DNA.
Mechanism
of action of Sulfonamides: Bacteriostatic
1. It
competes with PABA for the enzyme dihydropterate synthetase.thus inhibit folate
synthesis. Folate is necessary for synthesis of bacterial DNA or RNA.
Mechanism
of action of Trimethoprim: Bacteriostatic
1. It
inhibits the reduction of dihydrofolic acid (DHFA) to tetrahydrofolic acid
(THFA).
Collected and concise only for postgraduate students
