(Lecture) Actions of Antimicrobials Flashcards
Chemical substances that are produced by microorganisms that has the capacity to inhibit or kill other microorganisms.
Antibiotics
The lowest concentration of a drug that can inhibit bacterial growth.
Minimum-Inhibitory Concentration (MIC)
The lowest concentration of a drug that can still kill bacteria.
Minimum-Bactericidal Concentration (MBC)
Ratio of a toxic dose to the therapeutic dose; the higher the index, the more effective the chemotherapeutic agent.
Therapeutic Index
Characteristics of Antimicrobial Agents
● The agent must be in active form.
● The agent must be able to achieve concentration at the site of infection that is higher than the pathogen’s MIC to be effective.
● Must have selective toxicity.
_____ inhibit cell wall synthesis by binding to the end of the peptidoglycan, preventing transpeptidation.
Glycopeptides
Glycopeptides inhibit cell wall synthesis by binding to the end of the peptidoglycan, preventing _____
Transpeptidation
Glycopeptides inhibit cell wall synthesis by binding to the end of the _____, preventing transpeptidation
Peptidoglycan
What type of Antimicrobial Agents is this based on the description?
● Selective antibiotics with high therapeutic index
● Interferes with the biosynthesis of peptidoglycan
● The beta-lactam antibiotics form covalent complexes with enzymes that generate mature peptidoglycan molecule (transpeptidase enzymes that mediate peptidoglycan cross-linking)
● The active component of the beta-lactam family of drugs is the beta-lactam structure.
● Glycopeptides inhibit cell wall synthesis by binding to the end of the peptidoglycan, preventing transpeptidation.
Cell Wall Inhibitors
_____ prevents the formation of dihydropteroate through competitive inhibition of para-aminobenzoic acid with the enzyme dihydropteroate synthase
Sulfamethoxazole/SMZ
Sulfamethoxazole/SMZ (a sulfonamide) prevents the formation of dihydropteroate through competitive inhibition of para-aminobenzoic acid with the enzyme _____
Dihydropteroate synthase
Sulfamethoxazole/SMZ (a sulfonamide) prevents the formation of _____ through competitive inhibition of para-aminobenzoic acid with the enzyme dihydropteroate synthase
Dihydropteroate
_____ blocks the formation of the tetrahydrofolate by inhibiting dihydrofolate reductase.
Trimethoprim
Trimethoprim blocks the formation of the _____ by inhibiting dihydrofolate reductase.
Tetrahydrofolate
Trimethoprim blocks the formation of the tetrahydrofolate by inhibiting _____
Dihydrofolate reductase
What type of Antimicrobial Agents is this based on the description?
● The folic acid pathway provides essential precursor molecules needed for DNA biosynthesis
● Sulfamethoxazole/SMZ (a sulfonamide) prevents the formation of dihydropteroate through competitive inhibition of para-aminobenzoic acid with the enzyme dihydropteroate synthase
● Trimethoprim blocks the formation of the tetrahydrofolate by inhibiting dihydrofolate reductase.
Inhibitors of Folate Synthesis
These are necessary for DNA replication
Topoisomerases I, II, III, and IV
_____ affect DNA replication by targeting topoisomerases II (DNA gyrase) in Gram-negative bacteria and Topoisomerase IV in Gram-positive bacteria
Quinolones
Quinolones affect DNA replication by targeting _____ in Gram-negative bacteria and _____ in Gram-positive bacteria
Topoisomerases II
Topoisomerases IV
What type of Antimicrobial Agents is this based on the description?
● Topoisomerases I, II, III, and IV are necessary for DNA replication
● Quinolones affect DNA replication by targeting topoisomerases II (DNA gyrase) in Gram-negative bacteria and Topoisomerase IV in Gram-positive bacteria
Agents that Interfere with DNA Replication
_____ of DNA into RNA is mediated by RNA polymerase
Transcription
Transcription of DNA into RNA is mediated by _____
RNA polymerase
_____ targets the RNA polymerase subunit, blocking RNA chain elongation.
Rifampin
What type of Antimicrobial Agents is this based on the description?
● Transcription of DNA into RNA is mediated by RNA polymerase
● Rifampin targets the RNA polymerase subunit, blocking RNA chain elongation.
Agents that Interfere with DNA Transcription