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58 Cards in this Set
- Front
- Back
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What are the uses of blocking DNA replication or mRNA transcription (inhibitin nucleic acid synthesis)
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affects both types of cells (pro- and eu-)
not normally used to treat microbial infections used in research used to treat chemo they affect cancerl cells by slowing their replication (but they can also harm rapidly growing cells) |
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What are nucleotide analogs?
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have structure similar to normal nucleotides that make a false nucleotides to stop DNA synthesis
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What happens with a nucleotide analog is incorporated into a nucleic acid?
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distortion of nucleic acid to prevent further replication, transcription, or translation
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What is a nucleotide analog usually used against
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viruses
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What is more likely to incorporate a nucleotide analog?
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viral DNA polymerase
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What is more rapid than that in host cells?
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viral nucleic acid synthesis
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What are nucleotide analogs effective against besides viruses?
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rapidly dividing cancer cells
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What do quinolones and fluoroquinolones do?
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act against prokaryotic DNA gyrase but have little effect on eukaryotes or viruses
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What does rifampin do?
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binds to and inhibits the action of RNA polymerase during transcription
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What can block virus attachment?
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peptide and sugar analogs of attachment or receptor proteins (attachment antagonists)
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How can virus attachment be prevented?
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analogs, block receptor site, still in developmental stage
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What is the ideal antimicrobial agent?
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readily available, inexpensive, chemically stable, easily administered, nontoxic, nonallergenic, selectively toxic against a wide range of pathogens
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What is a narrow spectrum?
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attacks only a limited amount of pathogens
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What is the advantage to a narrow spectrum?
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less likely to kill normal flora
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What is the disadvantage of a narrow spectrum?
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must know exactly what you have
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What is a broad spectrum?
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kills a wide range of organisms
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What is the advantage of broad spectrum?
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cant know exactly what you use and you can use this before knowing what it is
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What is the disadvantage of broad spectrum
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kills normal flora and you can get other infections like antibiotic resistance or superinfection
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What is superinfection
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occurs after normal flora are disturbed
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What is considerations for efficacy of a drug?
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dosages required to be effective, route of administration, overall safety
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What do you want a drug to have?
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high concentration where the mos is located
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What type of antimicrobial is used before Id of pathogen
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broad spectrum
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What is efficacy ascertained by?
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diffusion susceptibility tests
minimum inhibitory concentration test minimum bactericidal concentration test |
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Is something with a larger zone of inhibition more effective
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don't know because smaller ones travel faster
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What is the lowest amount that the mos doesnt grow?
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MIC
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IF tetra has MIC 1.5 and X has MIC of 10.7, which is more effective?
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tetracycline, because use less to kill
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How can you tell MBC by plate?
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whatever section has lowest number with no growth
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What are some points about drug distribution in host
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should reach high concentration in target tissue
should not be inactivated by host distribution depends on route of administration |
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What application do you use if infection is external
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topical
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What type of route is simplest?
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oral
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Name some points about oral route
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simplest, lower drug concentration, safe administration, no reliance on health care provider, do not always follow prescribing information
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What are some points about intramuscular route
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requires needle for administration and concentration is never as high as IV administration
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What are some points about IV route
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requires needle or catheter, drug concentration diminishes as liver and kidneys remove it from circulation
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WHat must you know for route?
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how drug will be distributed to infective tissues
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What are some ways drugs may interact with each other?
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antangonism, no interaction, synergism
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What are some things that drugs interact with
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each other and food
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What are 3 main categories of side effects?
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toxicity, allergies, disruption of normal flora
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What does synergistic combination of drugs do?
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allow to be used in lower dosages to reduce side effects and minimize development of resistance or treat multiple infections
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What may drugs be toxic to?
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kidneys, liver, or nerves
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What may allergies be?
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life threatening: anaphylactic shock (extreme drop in BP)
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What may disruption of normal microbiota cause?
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secondary infection, overgrowth of normal flora (superinfection), greatest concern for hospitalized patients
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How do mos become resistant to drugs?
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some are naturally resistant, mutations of chromosomal genes (one in a million) followed by selection, or acquiring R plasmid via transformation, transduction, and conjugation
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What is R plasmid
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carries drug resistance gene
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What may a pathogen acquire at one time
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resistance to more than one drug
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What is a mos that is resistant to multiple drugs?
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superbug
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What is a mos that is resistant to 2 different mechanisms of drugs?
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cross resistance
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When is multiple resistance common?
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when R plasmids are exchanged
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Where does multiple drug resistance usually occur
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in hospitals and nursing homes due to constant use of drugs that elminates sensitive cells
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What may a drug resistant mos do?
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destroy drug, alter membrane to delay entry of drug, alter drug target, alter metabolic process and bypass inhibited pathway, pump drug out of cell
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How may a drug resistant mos destroy the drug?
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by a microbial enzyme (like penicillanase/ beta lactamase in staph aureus)
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How may a drug resistant mos alter the target of the drug?
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produce less sterol in the membrane, or alter ribosomes (tetracycline binds to 30S ribosomes if mos changes their 30S ribosomes, it can't bind)
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What should you use penicillin with?
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a beta lactamase inhibitor so penicillin will work
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What pathway is shut down if sulfa drug is present
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PABA PATHWAY : used to make tetra hydrafolic acid and if the mos doesn't make its own folic acid, sulfa won't be effective
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What pumps drugs out of the cell
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pseudomonas
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How do you retard resistance?
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maintain high concentration to overcome inhibition quickly, use combo of 2 or more synergistic drugs with different MOA, limit use to necessary cases, develop new variations of existin drugs
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What will a high concentration of drug do?
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long enough to kill sensitive cells and inhibit resistant cells long enough for immune system to destroy
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What type of drugs should you combine
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synergists
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What occurs with development of new variations of existing drugs
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novel side chains are added to original molecule
2nd generation and third generation drugs |
