Antimicrobial Chemotherapy - Mechanisms of Antibiotics Flashcards
(52 cards)
What is a bactericidal? And give an example
An antimicrobial that kills bacteria - e.g. Penicillin
What is a bacteriostatic? Give an example too
An antimicrobial that inhibits the growth of bacteria - erythromycin.
What makes an organism be considered sensitive?
if is it inhibited or killed by levels of the antimicrobial that are available at the site of infection
Why would an organism be considered resistant?
If the organism is not killed or inhibited by levels of antimicrobial available at the site of infection.
What is MIC?
Minimal inhibition concentration - the minimal conc of antimicrobial needed to inhibit visible growth of given organism.
What is MBC?
Minimal bacterial concentration - minimum conc of antimicrobial needed to kill a given organism .
What is a topical route of administration?
Applied to surface - skin or mucous membrane (e.g. Conjunctiva)
What is systematic administration?
Taken internally, orally or parentally
What is parental administration?
Administered either intravenously or intramuscularly- sometimes subcutaneously
What three mechanisms may antimicrobials kill bacteria by?
1) inhibition of cell wall synthesis
2) inhibition of protein synthesis
3) inhibition of nucleic acid synthesis
Name two b-lactams.
Penicillin and cephalosporin
What is targeted by b-lactams ?
Penicillin binding proteins - the enzymes required for cross linking carbohydrates to form peptidoglycan
After b-lactams do their bit, what kills the organism in the end?
Autolytic enzyme
Why don’t b-lactams affect humans
Humans cells don’t have cell walls
Why does benzyl penicillin, a naturally occurring antimicrobial, not kill gram negative organisms ?
Can’t get through their wall due to low permeability
Name two glycopeptides .
Vancomycin and teicoplanin
When do glycopeptides act when inhibiting the synthesis of the cell wall?
They act before b-lactams - they inhibit the assembley of peptidoglycan precursors
Do glycopeptides affect gram positive or gram negative bacteria?
Gram postive only - can’t get through the gram negative wall.
How are peptidoglycans administered?
Not orally as they are not absorbed by the GI tract, but are given parentally
Why must the IV for vancomycin be administered slowly over several hours?
It is toxic - may cause local tissue damage, oxotoxicity, nephrotoxicity and skin rashes
How can inhibition of protein synthesis undergo selective action?
Protein synthesis involves translation in ribosomes. But there is a difference in bacterial ribosomes and mamillion ribosomes
Name a aminoglycoside drug. (Targets protein synthesis)
Gentamicin
Name two macrolide drugs
Erthromycine and clarithromycin
What do macrolides and tetracyclines do?
Inhibit protein synthesis
