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28 Cards in this Set
- Front
- Back
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Selective Toxicity |
The property of some antimicrobial agents to be toxic for a microorganisms and nontoxic for the host |
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Chemotherapy |
- Treatment of disease with chemical substances |
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Antibiotic |
- Substance produced by microorganisms that in small amounts inhibits another microorganism |
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Antimicrobial drugs |
- Wholly synthetic substances to inhibit other microorganisms |
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Antibiotic resistance |
- Phenomenon in which formerly effective medications have less and less impact on bacteria |
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Spectrum of Microbial Activity |
- Range of distinctly different types of microorganisms affected by an antimicrobial drug - A wide range is referred to as a broad spectrum of activity |
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Broad Spectrum Antibiotic |
- Antibiotic that is effective against a wide range of both gram-positive and gram-negative bacteria |
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Superinfection |
- Growth of natural biota that has developed resistance to an antimicrobial drug being used - Superimposed growth, remains within normal area |
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Viral Infections |
- This type of infection is especially difficult to treat because the pathogen is within the human host's cells and because the genetic information of the pathogen is directing the human cell to make more of itself, rather than to synthesize normal cellular materials |
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Bactericidal Bacteriostatic |
Antimicrobial drugs can either - Kill microbes directly or - Prevent microbes from growing What are the terms defining this? |
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Inhibits 1. Cell wall synthesis 2. Protein Synthesis 3. Nucleic acid replication/transcription 4. Essential metabolite synthesis 5. Or Injures plasma membrane |
5 Major Action Modes of Antibacterial Drugs |
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80S 70S |
Eukaryotic cells have _____ (size) ribosomes whereas prokaryotic cells have _____(size) ribosomes. This difference in ribosomal structure accounts for the selective toxicity of antibiotics that affect protein synthesis. |
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- Binds to 50S portion and inhibits formation of peptide bond - Interferes with tRNA and mRNA-ribosome complex attachment - Changes shape of 30S portion, mRNA code is read incorrectly |
3 Ways Antibiotics inhibits protein synthesis |
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Persister cells |
- Antibiotics represent a disease for bacteria, when first exposed, susceptibility and mortality is high - The few survivors usually have genetic characteristics that accounts for their survival, and their progeny are similarly resistance |
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- Conjugation - Transduction - Plasmids - Transposons |
Genetic differences arise from random mutations - Give 2 examples of horizontal transfer - Give 2 examples of what drug resistance factors are carried on |
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Superbugs MRSA |
- Bacteria that are resistant to large numbers of antibiotics - Give example |
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1. Blocking entry 2. Inactivation by enzymes 3. Alteration of target molecule 4. Efflux of antibiotic |
4 Methods of Antibiotic Resistance |
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Natural |
Destruction or inactivation by enzymes mainly affects (Natural/Synthetic) antibiotics |
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Porins Periplasmic Space |
- Structure of Gram-negative bacteria cell walls that restricts absorption of many molecules and therefore are relatively more resistant to antibiotics - Even if antibiotic penetrate, some degrade before entering the cell membrane, in the _______________ ___________ |
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Rapid Efflux (Ejection) |
- Ability of certain proteins in plasma membrane of gram negative bacteria to expel from cell, preventing them from reaching an effective concentration |
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Therapeutic Index
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- Assessing risks against benefits when administering drugs. - Sometimes, the use of drugs together can cause toxic effects that do not occur when used individually - Sometimes, one drug may neutralize the other |
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Synergism
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- Chemotherapeutic effect of two drugs given simultaneously is sometimes greater than the effect of either given alone Ex: Penicillin damages bacterial cell walls so streptomycin can enter |
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Antagonism |
- Active opposition - when two drugs are less effective than either one alone, or when there is competition among microbes Ex: Tetracycline stops the growth of bacteria and thus interferes with penicillin which requires bacterial growth |
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Perfect storm
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- Increasing drug resistance combined with a decline in the development of new antibiotics
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- Understand the range of targets - Target the virulence factors (Cholera toxin) - Sequester iron - Antimicrobial Peptides - Phage Therapy - Bacteriocins
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6Ways to Develop Chemotherapeutic Agents VTIPBA |
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- Dormant or persister cells - Gram Negative - Laboratory media - Drug misuse |
4 Problems with Developing Antibiotics (2 Bacteria - 2 Other)
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Injuring the Plasma Membrane
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Action of Antimicrobial Drug: - Polypeptide antibiotics change membrane permeability - Antifungal drugs combine with membrane sterols |
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Inhibiting Essential metabolite synthesis
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- Antimetabolites compete with normal substrates for an enzyme - Sulfanilamide competes with para-aminobenzoic acid stopping the synthesis of folic acid |
