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14 Cards in this Set
- Front
- Back
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when was Penicillinase first reported?
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in 1940
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what facilitates increase in resistant strains of bacteria?
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agriculture
medical overuse of antibiotics chronic disease |
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what are the mechanism of transfer of resistance?
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F factors
Resistance Factors Transposons |
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what is the procedure of transfer of resistance?
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Transformation
Transduction Conjugation |
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how is resistance conveyed by microbes that have become resistant to Penicillin and Cephalosporin?
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beta-lactamase, hydrolyze beta-lactam ring to acid to inactivate most common natural and semisynthetic beta-lactams
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how are microbes resistant to aminoglycosides such as streptomyocin, gentamycin?
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inactivated by either acylation or phosphorylation
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what are the mechanisms of action for resistance?
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1. increased destruction of drug
2. alteration in antibiotic receptor 3. increased production of metabolite to overcome antibiotic analog 4. lack of sensitive pathway 5. intrinsic insensitivity |
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what occurs if a microbe alters the receptor that the antibiotic binds to?
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RESISTANCE
antibiotic is no longer permeable to cell |
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what may have occurred in the microbe that has altered the antibiotic receptor?
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may be due to changes in transport system, binding proteins, cell wall or cell membrane
Efflux which expedites transport of antibiotics out of cell |
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If there is a mutation or genetic exchange in a microbe what might this lead to?
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RESISTANCE
may lead to altered active site and no longer be recognized by target enzymes or substrate |
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Describe a microbe that has developed resistance to Streptomycin.
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Streptomycin binds to 30S ribosome resulting in wrapped ribosome leading to misreading of RNA
Resistant ribosomes no longer bind or may even become dependent on streptomycin |
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how is resistance to Sulfa gained?
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PABA and sulfa analog are similar
Enzyme recognizes Sulfa as substrate and makes non-metabolized intermediate Increased production of metabolite Resistance is due to overproduction of Pteridine |
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True or False
Sulfa drugs are ineffective against bacteria not synthesizing folic acid |
True
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what type of mechanism is used by Pseudomonas for resistance to antibiotics?
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Intrinsic insensitivity
Lack of permeability of antibiotic into cell -altered or ineffective transport or porin system Porins limit uptake to molecules of <600 daltons (Efflux system) |
