Students will learn to make selected clinical decisions in the context of nursing regarding using current, reliable sources of information, understanding of pharmacokinetics and pharmacodynamics, developmental physiologic considerations, monitoring and evaluating the effectiveness of drug therapy, ...
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
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