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29 Cards in this Set
- Front
- Back
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What are some basic properties of antibiotics?
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(1) make up 15-20% of drugs
(2) Curative (3) Selective (4) Resistance |
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What is the definition of antibiotic?
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A substance made by a microorganism that will stop the growth or kill other microorganisms.
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Can an antibiotic be completely synthetic?
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This actually is an antimicrobial but most people do not make this distinction, so yes, antibiotics include
(1) biosynthetic (2) semisynthetic (3) completely synthetic |
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What is the definition of bacteriostatic?
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An antibiotic that is bacteristatic will stop the growth of bacteria but that effect is reversible in the sense that if we remove the antibiotic, the bacteria will begin to grow again.
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What if we leave a bacteriostatic antibiotic long enough?
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§ If we leave them in long enough, we will eventually kill all the bacteria but in the short run it will stop growth. Sort of like holding your breath - if you hold your breath for a few minutes…really just stop but if you hold your breath for a day - you will die.
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Define Bacteriocidal.
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Antibiotics that kill bacteria. These effects are irreversible and are lethal.
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Why can you not combine bacteriostatic drugs with bacteiocidal drugs?
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Since bacteriocidal is effective when the bacteria are actively dividing, the bacteriocidal drug would be ineffective with a bacteriostatic drug (one that inhibits bacterial replication).
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Which type of antibiotic is most effective in suppartive lesions?
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Neither...
Bacteiostatic usually inhibit replication of bacteria so that one's own body may kill the bacteria with phagocytes and antibodies but with a supparitive infection, the phagocytes are destroyed through necrosis. Bacteriocidal drugs are also not effective. |
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How does an abscess effect antibiotics?
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(1) poor circulation - Ab concentration is difficult to achieve and supplies of Antibodies, phagocytes, oxygen, and nutrients decreases and wastes increase
(2) slow bacterial growth - lessen the effectiveness of bactericidal ntibiotcs (3) Host's cells lyse - release metabolites that the bacteria use to bypass the block created by the antibiotic **Drain pus from an abscess is important for optimal antibiotic action*** |
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What is the effect of glucocorticoids?
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Glucocorticoids are immunosuppressant and therefore someone who is taking them will be harder to treat with antibiotics.
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What other conditions will decrease the effectiveness of our immune system?
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- glucocorticoids
- radiation - various cancer drugs - certain cancers - AIDs |
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How does the GI tract effect antibiotics?
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- absorption of antibiotics
- acidity affects degradation of certain penicillins |
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How does the liver effect antibiotics?
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- liver affects the rate of drug metabolism altered
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How does the kidney effect antibiotics?
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- the kidney affects the rate of drug excretion affected
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How does agranulocytosis and leukemia affect antibiotics?
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It reduces the number of available phagocytes.
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How does the treatment of diseases with radiation, nitrogen mustards, or corticosteroids affect antibiotics?
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Reduces the numbe of available phagocytes.
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What diseases reduce antibody formation which limits the effectiveness of antibiotics?
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- agammaglobulinemia
- multiple myeloma - chronic lymphatic leukemia |
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How does uremia and diabetes mellitus affect antibiotics?
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- depresses host resistance
- limits effectiveness |
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What is a superinfection?
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A superinfection usually results from the outgrowth of indigenous, drug resistant bacteria or fungi normally held in check by the growth of other organisms.
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What are two possible ways drugs become resistant?
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(1) mutation and selection
(2) Plasmid infection |
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Describe mutation and selection.
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In this situation, if you look at a population of bacteria (10^8) perhaps out of that population there is one mutant that is going to be resistant to a particular antibiotic. Normally there is nothing else going on - this one mutation is just one mutation in the population. However, if you treat with an antibiotic - that will kill most of the bacteria but not the one that is resistant, we now select for the one bacteria. This type of resistance does occur. However, this is not the most prevalent type of resistance.
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Describe how plasmids induce resistance.
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□ Plasmids are small, double stranded, non-chromasomal accessory genes or circular pieces of DNA that are found in vectors. They contain several genes and each of these genes encode for a specific protein. Frequently, the protein that they encode for they are proteins that confer resistance.
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What form of resistance do most proteins take?
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The most prevalent drug resistant plasmid codes for an enzyme that destroys the antibiotic.
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What other forms may resistance proteins take?
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(1) decreased drug activation
(2) formation of an altered receptor (3) decreased permeability or uptake of the antibiotic by the bacteria |
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What are common problems with antibiotics?
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- prescribe the wrong antibiotic
- Inappropriate dose to kill the bacteria. . - Bacteria are resistant in some people but not in others. - Patient Compliance. |
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What antibiotics inhibit nucleic acid synthesis?
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Sulfonamides
Trimethoprim Rifampin Fluoroquinolones |
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What antibiotics inibit cell wall synthesis?
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Penicillins
Cephalosporins Vancomycin Isoniazid Bacitracin |
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What antibiotics inhibit protein synthesis?
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Aminoglycosides
Erythromycin Tetracylcines Clindamycin Chloramphenicol |
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What antibiotics effect the cell membrane?
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amphotericin B
Miconazole Fluconazole |
