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Q: What are the four important questions to answer before prescribing an antibiotic?
A: 1. Disorder is caused by infection. 2. Infection is a threat to patient. 3. Infection is sensetive to drug. 4. Appropriate route of administration.
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Q: What four characteristics are important when proposing a drug:
A: 1. effectiveness. 2. toxicity 3. spectrum 4. expense.
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Q: Patient factors to consider when prescribing a drug?
A: 1. History of clinical illness. 2. Ongoing pathologies. 3. Immune system status.
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Q: What are two exceptions to the rule that one should wait for organism culture before beginning antibiotic therapy?
A: 1. Gross appearance of infection is sufficient to diagnose. 2. Serious infection.
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Q: Should one always culture as a backup, even if one has begun broad-spectrum therapy?
A: Yes, always culture as a backup.
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Q: What does MIC stand for?
A: Minimum Inhibitory Concentration, important in determining drug sensitivities of the organism.
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Q: Should "overkill" drug concentrations be used in therapy?
A: Yes, because actual MIC at site of infection is unknown, high concentrations are bacteriocidal rather than bacteriostatic, and it discourages resistance.
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Q: How is antibiotic treatment initiated?
A: ASAP and at the largest possible dose.
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Q: How long after infection symptoms end should a patient continue treatment?
A: At least two days.
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Q: For what two reasons should one monitor drug concentrations?
A: 1. As a guide to dose. 2. To mimimize intoxication.
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Q: What two distribution principles should be considered in relation to the blood brain barrier?
A: 1. Lipid solubility of the drug. 2. Active transport out to the CSF.
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Q: What two distribution principles should be considered in relation to urine?
A: Resorption and active transport, both of which can concentrate drugs in the urine up to one thousand times.
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Q: How does an ideal antimicrobial drug effect microorganisms versus host?
A: An ideal antimicrobial drug ONLY effects the microorganism, not the host.
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Q: What is meant by the term broad spectrum antibiotic?
A: Drugs that are active against a large number of pathogens of many different types.
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Q: Is a drug's spectrum of action the same as its useful therapeutic range?
A: No.
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Q: Give 5 reasons why we use a therapeutic agents in combination.
A: 1. To improve efficacy. 2. Initial treatment of serious infection. 3. Treatment of mixed infections. 4. Allows use of lower, less toxic doses. 5. Prevent resistance.
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Q: When might one consider prophylactic antimicrobial therapy?
A: Surgery, travel in undeveloped countries, and epidemics.
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Q: What justifies prophylactic antimicrobial therapy?
A: 1. Probability of infection is greater than 5 percent. 2. Drug has high therapeutic index. 3. History of prophylactic succes with drug.
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Q: What are the four sources of drug resistance mutations and genes?
A: 1. spontaneous mutation. 2. transformation. 3. transduction (significant). 4. Conjugation (very significant).
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Q: How can you reduce the frequency of drug resistant strains?
A: Decrease overall frequency of use of drugs.
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Q: What is cross resistance?
A: When a drug resistance mechanism makes an organism resistant to many drugs within a class and possibly across classes.
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Q: Where is drug resistance most common?
A: In the hospital setting.
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Q: Can hospitals reduce drug resistance by implementing controls through protocol?
A: Yes.
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Q: What are 4 common adverse effects of antimicrobial action?
A: 1. Superinfection. 2. Hypovitaminosis. 3. Surge of microbial toxin release. 4. Diarrhea.
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Q: What type of antibiotic is more likely to result in a superinfection?
A: A broad spectrum antibiotic is more likely to result in superinfection than a narrow spectrum.
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Q: What are two adverse effects of antimicrobial drugs that are independent of drug mechanism?
A: Irritation and allergy.
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Q: How is Isoniazid used therapeutically?
A: Primary drug in all regimens, also prophylaxis.
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Q: How is Rifampin used therapeutically?
A: Excellent tuberculicidal drug, most rapid acting. Also useful for other bacterial infections.
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Q: How is Ethambutol used therapeutically?
A: Very effective with Isoniazid.
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Q: How are Pyrazinamide and Streptomycin used therapeutically?
A: Used when organism is resistant to Isoniazid, Rifampicin, and Ethambutol.
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Q: What are some of the difficulties with tuberculosis therapy?
A: Immunosuppressed patients, long therapy (6-24 months), organism grows slowly, rapid development of resistance, and all useful drugs possess toxicity problems.
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Q: What is the mechanism of action of Isonizid?
A: Inhibit synthesis of mycolic acid and DNA synthesis.
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Q: Is Isoniazid bacteriostatic or bacteriocidal?
A: Static is bacilli are resting, cidal if bacilli are growing.
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Q: What are the toxicities associated with Isoniazid?
A: Peripheral neuritis, hepatitis, and hypersensitivity reactions.
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Q: What is the mechanism of action of Rifampin?
A: inhibits RNA polymerase.
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Q: What are the toxicities associated with Rifampin?
A: Jaundice, tears and urine turn red-orange, induces hepatic metabolism of other drugs, GI distress, diarrhea.
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Q: What is the mechanism of action of Ethambutol?
A: Tuberculostatic, so never used alone.
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Q: What are the toxicities associated with Ethambutol?
A: Decreased visual acuity, impaired ability to perceive green, and may precipitate gout.
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Q: What is the mechanism of action of Streptomycin?
A: Aminoglycoside (same limited distribution and toxicities), must be administered parenterally.
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Q: What are the toxicities associated with Streptomycin?
A: Ototoxicity, vestibular toxicity, and nephrotoxicity.
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Q: What is the mechanism of action of Pyrazinamide?
A: Bactericidal
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Q: When is Pyrazinamide used?
A: When resistance problems require a third drug.
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Q: What are the toxicities associated with Pyrazinamide?
A: Liver necrosis, hyperuricemia, nausea, and vomitting.
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