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24 Cards in this Set
- Front
- Back
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What is an antibiotic?
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A substance PRODUCED BY A MICRO-ORGANISM that kills or inhibits other microorganisms.
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What is an antibacterial?
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A synthetic agent which has activity against bacteria.
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Sulphonamide and Fluoroquinolones are examples of what?
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Antibacterials.
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What is an antimicrobial?
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Any substance, natural to synthetic, that kills or inhibits growth of a micro-organism (without damaging the host.)
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What is the mechanism of action for Tetracycline?
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Inhibits bacterial protein synthesis -
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What antimicrobials act by inhibiting bacterial protein synthesis?
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Tetracycline,
Macrolides (Tylosin, Tilmicosin, Spiramycin, Tulathromycin, Erythromycin) Chloramphenicol |
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Which antimicrobials are bacteriostatic?
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Those that inhibit protein synthesis:
Macrolides & Lincosamides, Chloramphenicol, Tetracyclines, The antimetabolites: Sulphonamides & Diaminopyrimidines, |
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What are the 5 antimicrobial mechanisms of action?
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1) Inhibit protein synthesis,
2) Inhibit nucleic acid synthesis, 3) Disrupt cell walls, 4) Disrupt cell membranes, 5) Interfere w/ metabolic pathways |
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Which antimicrobials act by interfering with bacterial metabolic pathways?
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Sulfonamide & Trimethoprim
Disrupt Folic Acid synthesis, by out competing PABA and Dihydrofolate reductase (DHFR) respectively. |
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How is antimicrobial resistance
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1) Inherent resistance,
2) Chromosomal mediated resistance, 3) Transferable drug resistance: a) conjugation mediated by plasmids, b) transduction / viral transfer, c) transformation / direct uptake of DNA from environment |
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What is the limiting factor of aminoglycoside function?
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Oxygen - absolutely necessary to work / natural anaerobic resistance.
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What is the limiting factor of nitroimidazole function?
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Requires an anaerobic environment / natural aerobic resistance.
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What organisms are naturally resistant to B-lactams?
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a) Mycoplasms because they have no cell wall,
b) Gram-ve |
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Against which 5 antibiotics are plasmid mediated resistance by conjugation commonly given?
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Sulphonamide, Streptomycin, Beta-lactam, Tetracycline, Chloramphenicol
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What is MIC?
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The minimal inhibitory concentration:
the highest dilution at which there is no growth after incubation, a quantitative value that defines susceptibility under laboratory conditions and is used to determine drug dose. |
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What are the two kinds of post antibiotic effect?
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Time dependent: macrolides, lincosamides, B-lactams
Concentration dependent: Metronidazole, Fluoroquinolones, Aminoglycosides |
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Which antimicrobials are bactericidal?
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Beta lactams, aminoglycosides, nitrofurans, cephalosporins, Nalidixic Acid & Fluoroquinolones,
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What is a potential negative side effect of prolonged use of diaminopyrimidines?
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Erythrocyte dysfunction associated with folic acid deficiency. (Treatable)
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Name some fluoroquinolones licenced for use in vet med and the animals on which they are commonly used.
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Enrofloxacin - cats, dogs, exotics, pigs, poultry, cattle
Marbofloxacin - cats, dogs, pigs, cattle Ibafloxacin - cats & dogs Orbifloxacin - dogs Difloxacin - dogs & poultry Danofloxacin - food-producing animals |
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When is fluoroquinolone use contraindicated?
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In young, growing animals b/c of weigh-bearing cartilage erosion;
with other drugs metabolised by the liver, ex: methylxanthines; potentially neurotoxic in cats - at high end/OD may cause blindness, seizures, coma |
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Summarize the use of fluoroquinolones.
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Excellent for infections due to gram-ve aerobes (eg. P. aeruginosa), good for UTIs, good penetration into tissues, good in respiratory & enteric infections in ruminants / pigs / poultry, long t1/2 & PAE for once-a-day dosing, SHOULD NOT BE FIRST LINE AGENTS.
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Summarize the use of Lincosamides in animals.
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Gram+ve infections, particularly penicillin-resistant organisms or in penicillin-sensitive animals,
anaerobic infections, osteomyelitis, dermatitis (Staphs), treatment & prevention of swine dysentery, treatment of intestinal spillage during surgery, Clindamycin - potentially useful in Toxoplasma infections |
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What is the use of Tylosin?
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1) treating leptospirosis and potentially rickettsia infections,
2) mastitis (because of its short withdrawl period), 3) bovine pneumonia, footrot, mastitis, 4) management of mycoplasma in poultry Note: Should NOT be used in horses! |
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What are potential treatments of swine dysentery?
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Tiamulin,
Lincomycin NOTES: Do not use Tiamulin w/ ionophores, as myocardial toxicity from Ca++ influx. One-way cross resistance w/ Tylosin. Also, skin lesions have been reported. |
