Antibacterial drugs Flashcards
What does antimicrobial mean?
Chemical which inhibits the growth of microorganisms.
What is a broad spectrum antibiotic?
Antibiotic against a large bacterial genera. This is useful for polymicrobial infection and based on empirical usage (experience), has past benefits.
What is a narrow spectrum antibiotic?
Antibiotic against a limited bacterial genera such as gram positive or negative.
What connects the lipoglycan cell wall to the peptidoglycan layer?
Lipoproteins
What are the anti-bacterial properties?
Selective toxicity, bactericidal, slow emergence of resistance bacteria and have a narrow spectrum of activity.
What is bactericidal?
Kills bacteria
What is bacteriostatic?
Inhibits growth of bacteria
What is selective toxicity?
Avoid harming the host
How do antibiotics affect bacteria?
Target cell wall synthesis and cyptoplasmic membrane, metabolites for DNA synthesis, inhibiting protein synthesis/translation and nucleic acid synthesis
What is a beta lactam?
Antibiotic with a beta-lactam in their structure
What are the beta lactam antibiotics?
Penicillin, cephalosporin and glycopeptides which inhibit celll wall synthesis
How do cephalosporins work?
Cefuroxime is an cephalosporin which inhibits the transpeptidase enzyme penicillin binding proteins. It is well-tolerated and safe for breastfeeding.
What are the targets of glycopeptide antibiotics?
Vancomycin binds to the cell wall unit precursors in the cyptoplasm and blocks linkage with lipid for delivery. Beta lactam antibiotics can only target gram positive bacteria because it cannot cross the lipopolysaccharide cell wall in gram negative.
What is penicillin binding proteins?
Membrane associated proteins.enzyme involved in the formation of peptidoglycan cell wall which polymerise the bond between lysine and alaine via transpeptidasation.
How does the peptidoglycan form?
Peptidoglycan monomers are formed in the cyptoplasm and cross linked to bind to the lipid bactoprenol for delivery to existing peptidoglycan cell wall. It uses transpeptidation via transpeptidase enzymes penicllin binding proteins to form a link and create a mesh and reform the links.
What is the target of beta lactams excluding glycopeptides?
Inhibits the transpeptidase enzyme penicillin binding proteins for cross linking of peptidoglycan monomers to existing peptidoglycan membrane which inhibit cell wall synthesis.
What are the ribosomes for prokaryotes?
70s ribosomes with small 30s subunit and large 50s subunit
What are the ribosomes for eukaryotes?
80s ribosome with 40s small subunit and large 60s subunit.
Which drugs inhibit the small subunit of prokaryotes?
30s small subunit inhibited by aminoglycosides (gentamycine)and tetracyclins (oxatetracycline))
What is the effect of aminoglycosides?
Gentamycin is bactericidal by binding to 30s small ribosomal subunit on 16s ribosomal RNA
What is the target of tetracycline?
Oxatetracycline targets the 30s small ribosomal subunit on prokaryote ribosome. It can target eukaryotic ribosomes but has greater affinity for prokaryotic.