Chapter 10 Learning outcome Flashcards
Define Chemotherapeutic agents
Drugs that act against diseases
Define Antimicrobial agents
Drugs that treat infections
Define Semisynthetic agents
Chemically altered antibiotics that are more effective,
longer lasting, or easier to administer than naturally
occurring ones
Define Synthetic agents
Antimicrobials that are completely synthesized in a lab
Define Antibiotics
Antimicrobial agents produced naturally by organisms
Explain how semisynthetic and synthetic antimicrobials differ from antibiotics.
Antibiotics are produced naturally from an organism. Semisynthetic antimicrobials are chemically altered antibiotics, and synthetic are completely synthesized in a laboratory.
Provide some common antibiotics and semisynthetic agents and their sources
Penicillin: Originally derived from the fungus Penicillium, particularly Penicillium chrysogenum. It was the first antibiotic discovered by Alexander Fleming in 1928
Cephalosporins: These antibiotics are derived from the fungus Acremonium (formerly called Cephalosporium)
Ampicillin: A derivative of penicillin, it is synthesized from penicillin G.
Azithromycin: Semi-synthetic derivative of erythromycin.
Mechanism of Antimicrobial Action: Explain the principle of selective toxicity
Selective toxicity- principle by which an effective antimicrobial agent must be more toxic to a pathogen than to the pathogen’s host
Explain why antibacterial drugs constitute the greatest number and diversity of
antimicrobial drugs available.
because fungi, protozoa, and helminths-like their animal and human hosts- are eukaryotic chemoheterotrophs and share many common features.
List and explain the six mechanism by which antimicrobial drugs affect pathogens.
- drugs that inhibit cell wall synthesis: selectively toxic to certain fungal or bacterial cells, which have cell walls, but not to animals, which lack cell walls.
- Drugs that inhibit protein synthesis (translation) by targeting the differences btwn prokaryotic and eukaryotic ribosomes.
- Drugs that disrupt unique component of a cytoplasmic membraine
- drugs that inhibit general metabolic pathways not used by humans
- Drugs that inhibit nucleic acid synthesis
- Drugs that blocks a pathogen’s recognition of or attachment to its host.
inhibition of cell walls synthesis: Describe the actions and give examples of drugs that affect the cell walls of bacteria or fungi.
major structural component of bacterial cell wall is peptidoglycan later.
Actions:
1.Beta lactams- preventing the cross-linkage of NAM subunits
2. lipoglycopeptides- disrupt cell wall formation
3. bacitracin- blocks the transport of NAG and NAM across the cytoplasmic membrane to the wall.
4. Isoniazid and ethambutol- disrupt the formation of mycolic acid.
Inhibition of synthesis of bacterial cell walls: Write all the different ways or mode of
actions of how drugs that inhibit the synthesis of bacterial cell walls are being designed to work.
- echinocandins- (caspofungin)
- inhibit the enzyme that synthesizes glucan;
- without glucan,
- fungal cells cannot make cell walls,
- leading to osmotic rupture.
beta-lactams
-prevent cross-linkage of NAM subunits.
penicillin
cephalosporin
carbapenem
Lipoglycopeptides
-disrupt cell wall formation
-directly interfere with particular alanine-alanine bridges that link the NAM subunits in many g(+) bacteria.
-vancomycin and cycloserine
bacitracin
blocks the transport of NAG and NAM across the cytoplasmic membrane to the wall.
isoniazid and ethambutol
disrupt the formation of mycolic acid.
Inhibition of synthesis of fungal cell walls: Write one way or mode of action of how drugs that inhibit the synthesis of fungal cell walls are been designed to work.
- echinocandins- (caspofungin),
- inhibit the enzyme that synthesizes glucan
- without glucan.
- fungal cells cannot make cell walls.
- leading to osmotic rupture.
Define the term echinocandins as it relates to antimicrobial drugs.
Echinocandins are a group of originally natural antibiotics produced from a variety of fungal isolates that now have many semisynthetic derivatives. They inhibit synthesis of the major cross-linked glucan found exclusively in fungal cell walls by targeting β-1,3-d-glucan synthase.
Inhibition of protein synthesis: Describe the actions and give examples of six antimicrobial drugs that interfere with ribosomes
- Aminoglycosides and
- tetracyclines- target 30s ribosomal subunit
- chloramphenicol
- Lincosamides or macrolides
- antisense nucleic acid
- oxazolidinone
Interference with prokaryotic ribosomes: Write all the different ways or mode of actions of how drugs that inhibit protein synthesis are being designed to work
- Binding to the Ribosome
- Interference with tRNA Binding
- Inhibition of Peptidyl Transferase
- Disruption of Initiation or Elongation Factors
- Disruption of Ribosome Assembly or Stability
- Blocking mRNA Function
- Induction of Ribosome Stalling
Define aminoglycosides
Aminoglycosides are a class of antibiotics that inhibit bacterial protein synthesis by binding to the bacterial ribosome. They interfere with the translation process by causing misreading of mRNA and by inhibiting the initiation of protein synthesis. Aminoglycosides are effective against a wide range of gram-negative bacteria and some gram-positive bacteria.
Define Lincosamides
Lincosamides are a class of antibiotics that inhibit bacterial protein synthesis by binding to the 50S subunit of the bacterial ribosome. This binding prevents the formation of peptide bonds between amino acids, thereby inhibiting the elongation of the polypeptide chain during translation.
Define streptogramins
Streptogramins are a class of antibiotics that inhibit bacterial protein synthesis by binding to the bacterial ribosome. They interfere with translation by blocking the exit tunnel of the ribosome, preventing the elongation of the polypeptide chain
Define macrolides
Macrolides are a class of antibiotics that inhibit bacterial protein synthesis by binding to the 50S subunit of the bacterial ribosome. They interfere with translation by blocking the movement of the ribosome along the mRNA, thereby preventing the elongation of the polypeptide chain. Macrolides are effective against a wide range of gram-positive and some gram-negative bacteria, as well as atypical pathogens.
Define antisense nucleic acids
Antisense nucleic acids are synthetic nucleic acid molecules that are designed to bind to complementary sequences of mRNA. By binding to mRNA, antisense nucleic acids can block translation or promote degradation of the mRNA, ultimately leading to reduced expression of the target protein. Antisense nucleic acids have potential as antimicrobial agents by targeting essential bacterial genes, disrupting bacterial growth and survival.
Define oxazolidinones
Oxazolidinones are a class of antibiotics that inhibit bacterial protein synthesis by binding to the 50S subunit of the bacterial ribosome. They interfere with translation initiation and prevent the formation of the initiation complex, thereby inhibiting protein synthesis. Linezolid is an oxazolidinone antibiotic commonly used to treat infections caused by multidrug-resistant gram-positive bacteria
Interference with the charging of transfer RNA molecules: Write all the different ways or
mode of action for how drugs that inhibit protein synthesis are being designed to work.
- inhibition of Aminoacyl-tRNA Synthetases
- Disruption of Amino Acid Binding Sites
- Altering tRNA Structure or Function:
- Interference with Editing Mechanisms:
- Induction of tRNA Misacylation:
Disruption of cytoplasmic membranes: describe the actions of antimicrobial drugs
that interfere with cytoplasmic membranes.
Antimicrobial drugs that disrupt cytoplasmic membranes target the integrity and function of the cell membrane of microorganisms, causing leakage of cellular components and ultimately cell death.
Write all the different ways or mode of actions of how drugs that disrupt
cytoplasmic membrane are being designed to work
- Perturbation of Membrane Structure
- Formation of Pores or Channels
3.Disruption of Membrane Potential: - Altering Membrane Fluidity
- Inhibition of Enzymatic Activity
Inhibition of metabolic pathways: explain the action of antimicrobial drugs that
disrupt synthesis of folic acid.
Sulfonamides compete with PABA molecules for the active site involved in producing dihydrofolic acid, leading to a decrease in the production of THF and thus DNA and RNA
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