NRS 230 CLINICAL
PHARMACOLOGY LECTURE - 3
FINAL ANTIBIOTICS PRACTICE
EXAMS WITH EXPLANATIONS
,Selective toxicity - ANS--In antimicrobial therapy, selective toxicity means that a particular
antimicrobial drug has the ability to KILL or SUPPRESS a pathogen without killing or harming the host
How does selective toxicity work? - ANS--selectivity occurs because of the differences between the
cellular chemistry of mammals versus the cellular chemistry of microbes
-examples of how this selectivity occurs include:
1. disruption of bacterial cell wall
2. Inhibition of an enzyme unique to bacteria
3. disruption of bacterial protein synthesis
Types of selective toxicity - ANS-1. Disruption of the bacterial cell wall
-bacteria come encased in a hard inflexible cell wall which provides bacteria w/ protection
-high osmotic pressure, the wall protects the bacterium from pulling in too much fluid inside the cell,
which would cause swelling, disruption, and death of bacterium
-several families of antibiotics weaken and disrupt the bacterial cell wall thereby allowing for cellular
swelling and bacterial lysis
2. Inhibition of an Enzyme Unique to Bacteria
-Certain antibiotics select and inhibit specific enzymes that are critical to bacterial survival but are
not critical to OUR survival
3. Disruption of Bacterial Protein Synthesis
-The synthesis of protein is done by ribosomes in both bacteria and mammalian cells (mammalian
NOT identical to bacterial)
Classification of Antimicrobial drugs - ANS-1. Classification by Susceptible Organism
2. Classification by Mechanism of Action
Classification by Susceptible Organism - ANS-1. Species
-Gram Positive (species or type of bacteria)
-Gram Negative (species or type of bacteria)
-Antibacterial, antifungal, antiviral (the organisms they are active against)
2. Narrow-spectrum agent (active against a few species of microbes)
3. Broad-spectrum agent (against a wide variety of microbes)
, Classification of Mechanism of Action - ANS-1. Drugs that inhibit cell wall synthesis
-These drugs cause weakening of the cell wall; thus, promoting bacterial lysis and death
2. Drugs that increase cell membrane permeability
-increase the permeability of cell membranes causing leaking of the intracellular material
3. Drugs that cause lethal inhibition of protein synthesis
-The only drug in this group includes aminoglycosides (unclear why they cause death)
4. Drugs that cause nonlethal inhibition of protein synthesis
-These agent inhibits protein synthesis; thus they only SLOW microbial growth and do not KILL
5. Drugs that inhibit bacterial synthesis of DNA and RNA or disrupt DNA function
-These drugs work by inhibiting the synthesis of DNA or RNA
-This is done by either directly binding to nucleic acids or interacting with the enzymes required for
nucleic acid synthesis
-Also bind to DNA and disrupt its function
6. Antimetabolites
-These drugs work by disrupting specific biochemical reactions
7. Drugs that suppress viral replication
-most work by inhibiting specific enzymes
Bacteriostatic vs. Bactericidal - ANS-1. Bactericidal
-directly lethal to bacterial at clinical achievable concentrations
2. Bacteriostatic
-drugs that slow bacterial growth but do not cause cell death
--kills the bugs vs. slows them
--if using a bacteriostatic ABX it's important for a host to have a functioning immune system
Acquired resistance to antimicrobial drugs - ANS--Resistance (can be innate/natural or acquired)
-occurs overtime
-Organisms that were once highly sensitive to a particular ABX may over time become LESS
susceptible/sensitive to the ABX thus becoming resistant
-an antibiotic is rendered essentially useless once resistance has occured
-Acquired resistance can develop to several drugs
PHARMACOLOGY LECTURE - 3
FINAL ANTIBIOTICS PRACTICE
EXAMS WITH EXPLANATIONS
,Selective toxicity - ANS--In antimicrobial therapy, selective toxicity means that a particular
antimicrobial drug has the ability to KILL or SUPPRESS a pathogen without killing or harming the host
How does selective toxicity work? - ANS--selectivity occurs because of the differences between the
cellular chemistry of mammals versus the cellular chemistry of microbes
-examples of how this selectivity occurs include:
1. disruption of bacterial cell wall
2. Inhibition of an enzyme unique to bacteria
3. disruption of bacterial protein synthesis
Types of selective toxicity - ANS-1. Disruption of the bacterial cell wall
-bacteria come encased in a hard inflexible cell wall which provides bacteria w/ protection
-high osmotic pressure, the wall protects the bacterium from pulling in too much fluid inside the cell,
which would cause swelling, disruption, and death of bacterium
-several families of antibiotics weaken and disrupt the bacterial cell wall thereby allowing for cellular
swelling and bacterial lysis
2. Inhibition of an Enzyme Unique to Bacteria
-Certain antibiotics select and inhibit specific enzymes that are critical to bacterial survival but are
not critical to OUR survival
3. Disruption of Bacterial Protein Synthesis
-The synthesis of protein is done by ribosomes in both bacteria and mammalian cells (mammalian
NOT identical to bacterial)
Classification of Antimicrobial drugs - ANS-1. Classification by Susceptible Organism
2. Classification by Mechanism of Action
Classification by Susceptible Organism - ANS-1. Species
-Gram Positive (species or type of bacteria)
-Gram Negative (species or type of bacteria)
-Antibacterial, antifungal, antiviral (the organisms they are active against)
2. Narrow-spectrum agent (active against a few species of microbes)
3. Broad-spectrum agent (against a wide variety of microbes)
, Classification of Mechanism of Action - ANS-1. Drugs that inhibit cell wall synthesis
-These drugs cause weakening of the cell wall; thus, promoting bacterial lysis and death
2. Drugs that increase cell membrane permeability
-increase the permeability of cell membranes causing leaking of the intracellular material
3. Drugs that cause lethal inhibition of protein synthesis
-The only drug in this group includes aminoglycosides (unclear why they cause death)
4. Drugs that cause nonlethal inhibition of protein synthesis
-These agent inhibits protein synthesis; thus they only SLOW microbial growth and do not KILL
5. Drugs that inhibit bacterial synthesis of DNA and RNA or disrupt DNA function
-These drugs work by inhibiting the synthesis of DNA or RNA
-This is done by either directly binding to nucleic acids or interacting with the enzymes required for
nucleic acid synthesis
-Also bind to DNA and disrupt its function
6. Antimetabolites
-These drugs work by disrupting specific biochemical reactions
7. Drugs that suppress viral replication
-most work by inhibiting specific enzymes
Bacteriostatic vs. Bactericidal - ANS-1. Bactericidal
-directly lethal to bacterial at clinical achievable concentrations
2. Bacteriostatic
-drugs that slow bacterial growth but do not cause cell death
--kills the bugs vs. slows them
--if using a bacteriostatic ABX it's important for a host to have a functioning immune system
Acquired resistance to antimicrobial drugs - ANS--Resistance (can be innate/natural or acquired)
-occurs overtime
-Organisms that were once highly sensitive to a particular ABX may over time become LESS
susceptible/sensitive to the ABX thus becoming resistant
-an antibiotic is rendered essentially useless once resistance has occured
-Acquired resistance can develop to several drugs
