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42 Cards in this Set
- Front
- Back
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Acyclovir
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A synthetic purine analog that blocks DNA synthesis in certain viruses particularly the herpes simplex virus
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Aminoglycosides
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a complex group of drugs derived from soil actinomycetes that impares ribosomes function and has antibiotic potential, ex stroptomycin
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antibiotics
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a chemical substances from one microorganism that can inhibit or kill another microbe even in minute amounts
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beta-Lactamase
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An enzyme secreted by certain bacteria that cleaves the beta-lactam ring of penicillin and cephalosporin and thus provides for resistance against the antibiotic
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Cephalosporins
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A group of broad-spectrum antibiotics isolated from the fungus cephalosporiun
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Competitively inhibiting
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Control process that relies on the ability of metabolic analogs to control microbial growth by successfully competing w/ a necessary enzyme to halt the growth of bacterial cells
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Metabolic analog
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Enzyme that mimics the natural substrate of an enzyme and vies for its active site
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Narrow spectrum
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Denotes drugs that are selective and limited in their effect. for ex they inhibit either gram neg or gram pos bacteria, but not both
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Polymyxin
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A mixture of antibiotic polypeptides from Bacillus polymyxa that are particularily effective against gram neg bacteria.
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Resistance factors
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Plasmids, typically shared among bacteria by conjugation, that provide resistance to the effects of antibiotics
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Selectively Toxic
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property of an antimicrobial agent to be highly toxic against its target microbe while being far less toxic to other cells, particulary those of the host organism
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Semisynthetic
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Drugs which, after being naturally produced by bacteria, fungi or other living sources, are chemically modified in the laboratory
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Tetracyclines
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A group of broad-spectrum antibiotics w/ a complex 4-ring structure
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Sulfanamides
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Antimicrobial drugs that interfere with the essential metabolic process of bacteria and some fungi
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Broad Spectrum
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Antimicrobials effective against a wide variety of microbial types. For ex a drug effective against both gram-pos and gram neg bacteria
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Prophylaxis
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use of a drug to prevent imminent infection of a person at risk
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Antibiotics
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Naturally occurring antimicrobials.
Metabolic products of bacteria and fungi Reduce competition for nutrients and space. Bacteria Streptomyces, Bacillus, Molds Penicillium, Cephalosporium |
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Selective toxicity
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Drugs that specifically target microbial processes, and not the human host cellular processes. Ideal drug for what you want to kill
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Cell Wall Synthesis
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Bactericidal
Cycloserine – inhibits the formation of the basic peptidoglycan subunits Vancomycin – hinders peptidoglycan elongation Penicillin and cephalosporins – binds and blocks peptidases involved in cross-linking the glycan molecules |
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Nucleic acid synthesis
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Chloroquine – binds and cross-links the double helix.
Other quinolones – inhibits DNA unwinding enzymes. Viruses Asidothymidine (AZT) Analogs of purines and pyrimidines |
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Protein Synthesis
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Aminoglycosides
Binds the 30S ribosome Misreads mRNA. Tetracyclines Blocks attachment of tRNA. Chloramphenicol Binds to the 50S ribosome Prevents peptide bond formation |
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Cell Membrane
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Polymyxins
Interact with membrane phospholipids Distorts the cell surface Leakage of proteins and nitrogen bases. Anit-fungal Amphoterin B Forms complexes with sterols in the membrane Leakage Can affect human cell membranes (toxicity) |
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Folic Acid Synthesis
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Sulfonamides (sulfa drug) and trimethoprim
-Analogs -Competitive inhibition -Prevents the metabolism of DNA, RNA, and amino acid |
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Penicillin
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-Penicillin chrysogenum
-A diverse group (1st, 2nd , 3rd generations) Natural (penicillin G and V) -Semisynthetic (ampicillin) Structure Thiazolidine ring Beta-lactam ring Variable side chain (R group) |
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Penicillin continued
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-Resistance – if bacteria contain penicillinases
-Inhibits cell wall synthesis -Treat streptococci, meningococci, and spirochete infections |
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Cephalosporin
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-Cephalosporium acremonium (mold)
-Widely administered today Diverse group (natural and semisynthetic) -Structure similar to penicillin except Main ring is different Two sites for R groups |
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Cephalosporin, continued
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-Resistant to most pencillinases
-Broad-spectrum – inhibits cell wall synthesis -3rd generation drugs used to treat enteric bacteria, respiratory, skin, urinary and nervous system infections |
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Aminoglycosides
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-Streptomyces and Micromonospora
-Structure Amino sugars and an aminocyclitol ring -Broad-spectrum -Commonly used to treat -bubonic plague and sexually transmitted diseases -Inhibits protein synthesis |
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Tetracycline
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-Streptomyces
-Structure – Diverse complex series of rings -Broad spectrum and low cost -Commonly used to treat sexually transmitted diseases -Side effects – gastrointestinal disruption -Inhibits proteins synthesis |
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Chloramphenicol
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-Streptomyces
-Structure - nitrobenzene structure -Broad-spectrum -Only made synthetically today -Treat typhoid fever, brain abscesses -Side effects – aplastic anemia -Inhibits protein synthesis |
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Erythromycin
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-Streptomyces
-Structure – macrolide ring -Broad-spectrum -Commonly used as prophylactic drug prior to surgery -Side effects - low toxicity -Inhibits protein synthesis |
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Sulfanomides (Sulfa drupgs)
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-Synthetic drug
-Based on sulfanilamides -Used in combination with other synthetics such as trimethoprim -Commonly used to treat pneumonia in AIDS patients -Inhibits folic acid synthesis |
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Polyenes
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-Antifungal
-Structure – large complex steroidal structure -Some toxicity to humans -Commonly used for skin infections -Targets the membrane - lost of selective permeability |
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Antiviral
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-Limited drugs available
-Difficult to maintain selective toxicity -Effective drugs – target viral replication cycle Entry Nucleic acid synthesis Assembly/release -Interferon – artificial antiviral drug |
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Antimicrobial Resistance
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Resistance factors
New enzymes Permeability Alter receptors Change metabolic patterns Natural selection New approaches |
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New Approaches
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Increase drug resistance requires new approaches for developing effective antimicrobials
-Prevent iron –scavenging capabilities -Inhibit genetic controls (riboswitches) -Probiotics and prebiotics |
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Drug and Host Interactions
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Toxicity to organs
Allergic reactions Suppress/alter microflora Effective drugs |
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Kirby-Bauer Test
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Sensitivity test such as the Kirby-Bauer Test can be used to determine the effectiveness of a drug by measuring the zone of inhibition.
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MIC minimum inhibitory concentration
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The lower the MIC, the more effective the drug is toward combating the bacterium.
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E-Test
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It determines the minimum amount of drug to use in the correct amount of time
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Zone of inhibition
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the area around the drop of antibiotic
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Spectrum
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What range does this drug work
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