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71 Cards in this Set
- Front
- Back
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What are drugs?
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chemicals that affect physiology in any manner`
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What are drugs that act against diseases?
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chemotherapeutic agents
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What are drugs that treat infection?
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antimicrobial agents
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What did Paul Ehrlich do?
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create "magic bullets" an arsenic compound that kill trypanosomes and another that worked against treponemes
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What did alexander fleming do?
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discover that penicillin was released from penicillium
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What are antibiotics?
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antimicrobial agents that are produced naturally by organisms
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What did Gerhard Domagk do?
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find sulfanilimide (sulfa drug) the first antimicrobial agent used to treat a wide array of infections (chemically synthesized)
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What are semisynthetics?
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chemicals are used to modify antibiotics and make them more effective
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What is the key to antimicrobial action?
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selective toxicity
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What is selective toxicity?
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being able to affect something that is unique to bacteria that will not disrupt the host
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What is something that is toxic to parasite/pathogen but not to the host?
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selective toxicity
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What constitute the largest number and diversity of antimicrobial agents?
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antibacterial drugs
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What is order of amt of drugs of type?
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antibacterial> antieukaryotic drugs > antiviral drugs
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What 2 things must occur in order to be an antibiotic?
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must inhibit or kill other organisms
must be effective at a very low dose |
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What does penicillin do?
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inhibit peptidoglycan in the cell wall or prokaryotes: we don't have peptidoglycan so it doesn't harm us
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Why is it harder to treat eukaryotic infections and viral infections?
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eukaryotic- we have eukaryotic cells so it could kill our cells
virus- obligate intracellular parasites: can kill our cels |
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What are some types of antimicrobial action?
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inhibition of...
cell wall synthesis pathogen attachment DNA or RNA synthesis general metabolic pathway protein synthesis and disruption of cytoplasmic membrane |
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What are cross linked in prokaryotic cell walls?
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NAG and NAM
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What can those that inhibit cell wall synthesis do?
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prevent export of NAG and NAM or inhibit cross linking
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What do most common cell wall inhibitors do?
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prevent cross linking of NAM subunits
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What are the most prominent in the group of those that inhibit cell wall synthesis and how do they work?
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beta lactams: their functional groups are beta lactam rings: they bind to enzymes that cross link NAM subunits and bacteria have weakened cell walls and eventually lyse
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What is the natural beta lactam antibiotic?
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penicillin G excreted by mold
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What are beta lactams other than pen G
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semisynthetic
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What happens to bacteria w/o beta lactam ring?
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lost function and burst
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What are some disadvantages of the simplest beta lactams?
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effective only against Gram positive
Pen G is sensitive to stomach acid (cant take orally: need injection) |
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What are some advantages to semisynthetic derivatives of beta lactam?
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more stable in acidic env't (can take orally)
more readily absorbed less susceptible to deactivation more active against more types of bacteria (broader spectrum) |
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What does staph aureus have that destroys beta lactam antibiotics?
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penicillinase: beta lactamase
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Why does Pen G only work on gram positive?
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because they have a thick peptidoglycan cell wall and G- are resistant due to the outer porin membrane
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What do vancomycin and cycloserine do?
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interfere with particular alanine-alanine bridges that link NAM subunits in many G+
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What does bacitracin do?
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blocks secretion of NAG and NAM from cytoplasm
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What makes bacitracin?
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bacillus
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What does isoniazid and ethambutol do?
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disrupt formation of arabinogalactan-mycolic acid in mycobacterial species (TB or leprosy)
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What is important in the cell wall of mycobacterium?
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arabinogalactan-mycolic acid
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Will antibiotics that inhibit cell wall synthesis have any effect on existing peptidoglycan layer?
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no, they just prevent NEW peptidoglycan
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Will antibiotics that inhibit cell wall synthesis affect only growing cells?
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yes
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Will antibiotics that inhibit cell wall synthesis have an effect on plant or animals cells with no peptidoglycan?
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no, they only effect peptidoglycan
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What are prokaryotic ribosomes?
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70S (30S and 50S)
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What are eukaryotic ribosomes?
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80S (40S and 60S)
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What can drugs that inhibit bacteria protein synthesis do?
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selectively target translation;
they can damage mitochondria because they contain 70S ribosomes |
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What type of drug is an aminoglycoside?
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streptomycetes
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What do aminoglycosides do?
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cause misbinding between codon and anticodon: cause change in 30S shape and causes mRNA to be misread
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What does tetracycline do?
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block binding between codon and anticodon by blocking the docking site of tRNA
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What does chloramphenicol do?
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binds to 50S ribosomes and blocks binding of amino acids for tRNA
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What does macrolide do?
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binds to 50S subunit, blocking proper mRNA movement through ribosome and synthesis stops: ribosome is frozen and there is no protein synthesis
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What type of drug is erythromycin?
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macrolide
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What is a new approach that is not an antibiotic to stop protein synthesis in bacteria?
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antisense nucleic acid: ribosome cannot bind to mRNA and there is no protein synthesis
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How do drugs disrupt the cytoplasmic membrane?
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become incorporated into it and damage its integrity
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What does Amphotericin B (polyene) do?
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attaches to ergosterol found in fungal membranes
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What type of drug is polyene or Amphotericin B?
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antifungal
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Why are humans somewhat susceptibel to polyene?
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cholesterol is similar to ergosterol
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What is not susceptible to polyene?
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bacteria because they lack sterols
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What does polymyxin do?
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disrupts cytoplasmic membranes of G- and they're toxic to human kidneys
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How do we use polymyxin?
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only topical because orally can damage our kidneys
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What is in neosporin?
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polymyxin
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What type of drug is polymyxin?
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microbiocidal
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How can amphotericin disrupt the cytoplasmic membrane?
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makes a pore and the cell becomes leaky
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When can antimetabolic agents be effective?
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when differences exist between metabolic processes of pathogen and host
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What type of drugs are quinolones?
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antimetabolic agents
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What do quinolones do?
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interfere with metabolism of malaria parasites
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What do heavy metals do?
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inactivate enzymes
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Can heavy metals be used in humans?
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no, toxic to our cells
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What are some other ways that can inhibit metabolic pathways?
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disrupt tublin polymerization and glucose uptake by many protozoa and parasitic worms
block activation of viruses metabolic antagonists |
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What do sulfa drugs do?
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inhibit metabolic pathways: analogs of PABA and bacteria use PABA to make growth factor to make folic acid
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What is PABA
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para amino benzoic acid
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Where do humans get folic acid?
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from diet because we don't make it
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What type of effect does trimethorpin have?
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synergistic
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What will a bacteria do if theres enough sulfa?
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take it in place of the PABA group
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What does trimethoprim do?
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binds to the enzyme invovled in conversion of dihydrofolic acid to THF
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Are humans affected by trimethoprim?
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no, because we don't make our own folic acid
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What do antiviral agents do?
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target unique aspects of viral metabolism
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What do amantadine, rimantidine and weak organic bases do?
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neutralize acidity of phagolysosome and prevent viral uncoating (increase the pH in phagolysosome)
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