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What is the triangle of antimicrobial therapy?
- defense mechanisms of animal <--> infection
- drug disposition (ADME) <--> drug side effects in animal
- organism death or inhibition by drug <--> resistance of microbe to drug
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What are the characteristics of "drug disposition"?
- Absorption
- Distribution
- Metabolism
- Elimination
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Describe the absorption aspect of drug disposition.
- depends on route of administration
- Parenteral: IV has maximum bioavailability
- Oral: bioavailability impacted by whether drug is weak acid or base (weak acids absorbed best)
- Topical: depends on skin vascularity and drug properties
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When given enterally, ________ drugs are absorbed better than ________ drugs.
weak acid; weak base
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What is Vd?
Volume of distribution= volume of tissue to which a drug would be distributed, if present at same conc as measured in plasma
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Higher Vd-->
penetration to more tissue
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Vd is impacted by...
lipophilicity and binding to plasma proteins
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Describe the metabolism aspect of drug disposition.
- LIVER METABOLISM (most common)
- Phase I: cytochrome P450--> reduction and oxidation--> activation , inactivation, no change, toxicity
- Phase II: conjugation via glucuronidation (poor in cats), sulfation (poor in pigs), acetylation (poor in dogs)--> inactivation
- Elimination: urine or bile/ feces
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What are potential types of side effects of drugs?
- dose-related/ conc-dependent
- idiosyncratic- NOT conc-dependent, rather individual animal-dependent
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What microbes have acquired resistance [big deal rn]? (4)
- Staphylococcus
- Entercoccus
- gram negative enterics
- Pseudomonas aeruginosa
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Contrast intrinsic resistance with acquired resistance.
- Intrinsic: resistance due to inherent metabolic attributes of the organism
- Acquired: organism should be susceptible to antimicrobial BUT is not, due to mutations or acquired DNA (plasmids, transposons, bacteriophage)
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What are the common clinically relevant aerobic/ facultative gram positive bacteria?
- Cocci: Streptococcus, Staphylcoccus, Enterococcus
- Filamentous rods: Actinomyces, Nocardia
- Roads: Corynebacterium, Listeria, Erysipelothrix, Truperella, Rhodococcus
- Giant rods: Bacillus
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What are the common clinically relevant aerobic/ facultative gram negative bacterial?
- Enteric: E. coli, Klebsiella, Enterobacter [<-- coliforms], Citrobacter, Serratia, Proteus, Salmonella, Campylobacter
- Non-enterics: Haemophilus, Pasteurella, Mannheimia, Histophilus, Bordatella, Pseudomonas, Acinetobacter, Francisella, Moraxella
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What are the clinically important gram positive obligate anaerobes? (3)
- Clostridium
- some Actinomyces
- Peptostreptococcus
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What are the clinically important gram negative obligate anaerobes? (4)
- Bacterioides
- Fusobacterium
- Prevotella
- Porphyromonas
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Describe Mycobacteria.
gram + rods, acid fast
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What are the 4 genera of spirochetes?
- Leptospira
- Borrelia
- Brachyspira
- Treponema
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Describe Mycoplasma.
- fastidious
- no cell wall (neither gram neg or pos)
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What are intracellular fastidious or arthropod-borne microbes? (6)
- Ehrlichia
- Coxiella
- Bartonella
- Anaplasma
- Chlamydophila
- Chlamydia
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What is the difference between colonization, infection, and contamination?
- Colonization: bacteria propagate while maintaining a commensal or symbiotic relationship with host
- Infection: bacteria invade host tissue and cause pathology (damage and inflammation)
- Contamination: mechanical transfer of bacteria to site
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In a cat or dog, which beta-strep is most likely (from any body site)?
Steptococcus canis
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What microbes affect the integument in cats (commonly)? (2)
- Staphylococcus
- Pseudomonas aeruginosa
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What microbes are commonly isolated from wounds/ draining tracts in cats? (9)
- Staphylococcus
- Pseudomonas aeruginosa
- Pasteurella multocida
- Actinomyces
- Nocardia
- Enterics
- Streptococcus canis
- Anaerobes
- Radpidly growing Mycobacteria
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What are the sterile body sites? (10)
- Blood
- Cystocentesis urine
- Thoracocenteis fluid
- Abdomenocentesis fluid
- Arthrocentesis fluid
- Cerebrospinal fluid
- Parenchymous organs
- Fetal stomach contents
- Facial sinuses, middle ear
- Muscle, fat, subcutis
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All beta-streps are sensitive to __________.
penicillins
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