Antibiotics Action and Resistance

Mind Map by subahos6, updated more than 1 year ago
Created by subahos6 over 5 years ago


Mind Map on Antibiotics Action and Resistance, created by subahos6 on 12/29/2014.

Resource summary

Antibiotics Action and Resistance
1 Cell Wall Synthesis Inhibitors
1.1 Beta Lactams
1.1.1 Flucloxacillin
1.1.2 Amoxicillin + Clavulanic Acid Co-Amoxiclav Beta Lactamase Inhibitor
1.1.3 Phenoxymethylpenicillin
1.1.4 Action Bacteriocidal Contains Beta Lactam Ring Binds Pencillin Binding proteins and Inhibits them PBP binds D-ala-D-Ala at end of peptidoglycan precursor to crosslink the peptidoglycan and form cell wall at final stage Leads to accumulation of precursor cell wall units and eventual cell lysis
1.1.5 Cephalosporins Ist Generation Cefradine 3rd Generation Cefixime Ceftriaxone Cefotaxime Increased gram negative antimicrobial properties
1.1.6 Benzylpenicillin
1.1.7 Penicillin
1.1.8 Ampicillin
1.1.9 Resistance Target site Modify existing PBP so lower binding affinity import gene coding resistant PBP synthesis PBP's with low affinity so normal ones blocked but LA can continue to build Access to target site Lose porin to decrease permeability of memb to restrict entry Pump out more with increased efflux pumps Beta Lactamases increase to catalyse hydrolysis of beta lactam ring causing inactivity
1.2 Glycopeptide
1.2.1 Teicoplanin for MRSA
1.2.2 Vancomycin
1.2.3 Action Bacteriocidal too large to penetrate gram -ve bac Inhibits peptidoglycan synthesis thus interfering with cell wall synthesis Binds d-ala-d-ada at end of pentapeptide chians part of gowing cell wall. Inhibits transglycosylation and prevent incorp of new subunits
1.2.4 Resistance Altered glycopeptide target end in d-ala-d lac or d-ala-d-ser VanA, vanB, VanD encode ligase to alter it
2 Protein Synthesis Inhibitors
2.1 Aminoglycosides
2.1.1 Gentamicin
2.1.2 Action Bacteriocidal Binds to specific proteins in 30S ribosomal subunit Interferes with binding of fmet-tRNA Prevents formation of initiation complexes from which protein synthesis proceeds Causes misreading of mRNA codons Doesn't penetrate tissues and bone well
2.1.3 Resistance Target site Alter 30S ribosomal subunit Access cell wall permeability Energy dependent transport across cytplasmic membrane Produce amnoglycoside modifying enzymes modify to inactivate
2.2 Tetracyclines
2.2.1 Oxytetracycline
2.2.2 Doxycycline
2.2.3 Tetracycline
2.2.4 Action Bacteriostatic Binds small ribosomal subunit prevents aminoacyl tRNA from entering acceptor sites Selective- better uptake by prokaryotic cells
2.2.5 Resistance Alter target riboosmal unit Access New cytoplasmic membrane proteins syn th- increased efflux
2.3 Chloramphenicol
2.3.1 Action Bacteriostatic Targets 50s subunit blocks action of peptidyl transferase- prevent peptide formation
2.3.2 Resistance Alter ribosome Plasmid mediated enzymatic inactivation Actetyl transferase acetylates drug- fails to bind
2.4 Macrolides
2.4.1 Azithromycin
2.4.2 Erythromycin
2.4.3 Action Bacteriostatic Binds 23D rRNA in 50A subunit of ribosome Blocks translocation step in prot synth prevents release of tRNA after peptide bond forms
2.4.4 Resistance Alter 23S rRNA by methylation of 2 adenine nucleotides inRNA Access Efflux mech Methylase enzyme may be inducible or constitutive
2.5 Lincosamide
2.5.1 Clindamycin Bacteriostatic Blocks ribosomes Binds 50S rRNA of ribosome subunit Aerobic gram +ve NOT enterococci and Anaerobic gram -ve Can't do gram -ve too big to pass membrane SE C.difficle assocaited colitis
2.6 Fusidic Acid
2.6.1 Action Bacteriostatic Forms stable complex with elongation factor EF-G guanosine diphosphate ribosome Only for Staph bac Not active for gram -ve IV SE Jaundice
2.6.2 Resistance Altered EF-G target
3 Nucleic Acid Synthesis Inhibitors
3.1 Quinolones
3.1.1 Ciprofloxacin
3.1.2 Ofloxacin
3.1.3 Action Bacteriocidal Interfere with replication of bacterial chromosome Inhibits bacterial DNA gyrase and topoisomerase IV Gyrase produces and removes supercoils in DNA ahead of the replication fork during replication. Top similarly removes.
3.1.4 Resistance Target site alter to affect binding permeability, efflux Acetylation inactivation
3.2 Metronidazole
4 RNA Polymerase Inhibitors
4.1 Rifampicin
4.1.1 Action Bactericidal Binds DNA dependent RNA polymerase blocks mRNA synthesis
4.1.2 Resistance Chromosomal mutations alter RNA polymerase target. Lowered affinity.
5 Folate Synthesis Inhibitors
5.1 Sulphonamides
5.1.1 Sulfamethoxazole + trimethoprim Co-trimoxazole
5.1.2 Action Compete with para amino benzoic acid for active site of dihydropteroate synthase DS catalyses reaction in synthesis of tetrahydrofolic acid THFA required to synth purine and pyrimidine nucleic acids Bacteriostatic
5.1.3 Resistance Plasmid mediated genes coding for altered DS but unchanged affinity for PABA
5.2 Trimethoprim
5.2.1 Action Bacteriostatic Prevent THFA synth by inhibiting DHFR
5.2.2 Resistance Plasmid-encoded DHFR with altered affinity got trimeth allow synth Chromosomally encoded overproduction of DHFR
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