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48 Cards in this Set

  • Front
  • Back
What is the definition of antibiotics?
Antimicrobial substances produced by living organisms
What organism produces Penicillin G?
A mold called P. chrysogenum
What is the mechanism Penicillin uses?
Acts at last stage of bacterial cell wall synthesis; defective cell wall = cell lysis
2. bacteriocidal
What is Penicillin effective against?
*Only actively growing & dividing bacteria
1. Gram +'s primarily
2. At high doses, Gram -'s
What are Penicillin's therapeutic limitations?
1. Degraded by gastric acids (not administered orally)
2. Inactivated by B-lactamase made by Gram -'s and Staphylococci (Staph)
What is "special" about synthetic and semisynthetic penicillin?
1. Overcomes some of the disadvantages of Pen/G
2. Broader spectrum of targets
What are the groups of synthetic and semisynthetic penicillin? (I think this is what these names are)
1. Aminopenicillins
2. Carboxypenicillins
3. Ureidopenicillin
4. 6-methoxypenicillin
What are the types of aminopenicillins?
1. ampicillin
2. amoxicillin
3. hetacillin
What are the types of carboxypenicillins?
1. carbenicllin
2. ticarcillin
Penicillin as a group is toxic to what two types of animals? What 3 types of animals are hypersensitive to it?
1. Toxic to guinea pigs & hamsters
2. Dogs, cats, horses are hypersensitive
How is penicillin administeres?
IM, sub Q, IV, Orally, topically (depending upon class)
What are cephalosporins?
Semisynthetic derivatives of a compound produced by a fungus
What is the mechanism of action for cephalosporins?
1. Inhibit synthesis of a bacterial cell wall component
2. bacteriocidal
What is cephalosporins spectrum of targets?
1. similar, but broader than penicillin
2. Gram +'s and Gram -'s
3. Less susceptible to B-lactamase
List the different "generation" of cephalosporins based on chronology of discover, chemical structure, and therapeutic activity
1. cephalexin (keflex)
2. cephazolin (kefzol)
3. cephapirin (cefadyl)
What are Cephalosporins used to treat?
Bacterial infections of the respiratory, urinary and genital tracts, soft tissues, bones, joints, and skin
Is cephalosporin toxic to the animal? If so, what can it cause?
Minimally toxic, can cause vomitiong, diarrhea when used orally
What does Aminoglycoside target (ie: its mechanism of action)
Interferes with bacterial protein synthesis by causing misreading of the genetic code of mRNA
What is the spectrum of targets of aminoglycosides
Certain gram +'s and Gram -'s
Extensive bacterial resistance has developed to what four medicines?
1. streptomycin
2. dihydrostreptomycin
3. neomycin
4. kanamycin
What are the two more frequently used forms of aminoglycosides?
amikacin and gentamicin
How are aminoglycosides administered?
1. poorly absorbed from GI tract
2. Administered parenterally
What is the toxicity of aminoglycosides?
High degree of toxicity
1. nephrotoxicity
2. ototoxicity
What is the mechanism of action of Tetracyclines?
1. inhibit bacterial protein synthesis
2. bacteriostatic
What is Tetracyclines spectrum of activity?
1. Broad
2. Certain aerobic, anaerobic, Gram +, Gram - bacteria, spirochetes, mycoplasmas, rickettsiae, chlamydia, and protozoa
What are the group members of tetracyclines?
1. Tetracyclines (Panmycin, Achromycin, Tetracyn)
2. Oxytetracycline (terramycin)
3. Chlortetracyclin (aureomycin)
What are some problems associated w/tetracyclines?
1. development of resistant bacteria
2. toxicities: GI disturbances such as vomiting and diarrhea due to altered gut flora, Nephrotoxicity, and Anaphylaxis
3. Staining of teeth
How does tetracycline stain the teeth?
1. becomes fixed in growing osseous structures
2. may stain teeth of puppies & kittens if administered to bitch or queen during last 2-3 weeks of gestation or if given to the neonate in 1st months of life
What produces Erythromycin?
Streptomyces erythreus (macrolides)
What is the mechanism of action of Erythromycin?
1. inhibits RNA dependent bacterial cell protein synthesis
2. bacteriostatic
What is the spectrum of activity of Erythromycin?
1. Primarily against Gram +'s
2. Strep, Staph, Borrelia, Erysipelothrix, Clostridium Legionella
What are problems with erythromycin?
Increasing bacterial resistance
What is the toxicity of Erythromycin?
1. Relatively low
2. Nausea, vomiting, diarrhea
How is erythromycin administered?
Primarily orally
What is Nitrofuran from?
Chemical derivatives of 5-nitrofuraldehyde
What is the mechanism of action of Nitrofurans?
1. cause bacterial DNA strand to break
2. Interfere w/many bacterial cellular enzymes
3. Bacteriocidal or static (depends on susceptibility of organism and amount of drug at infection site)
What's Nitrofurans spectrum of activity?
Broad spectrum
Is bacterial resistance a problem in Nitrofurans?
Nitrofurans are one of the few antibiotics that are effective in the presence of what?
Blood and pus; this allows them to be used as a topical wound ointment
When is Nitrofurans used pareterally (orally) and to treat what?
Used most commonly to treat urinary tract infections when other drugs have failed
What is the toxicity of Nitrofurans?
May cause vomiting and diarrhea when given orally
What is the mechanism of action of Trimethoprim?
Interferes w/an enzyme necessary for the formation of normal nucleic acids
What is the mechanism for Sulfonamides?
Inhibits bacterial synthesis of dihydrofolic acid
What's the result of using Trimethoprim and Sulfonamides together?
Result is synergistic and results in a bacteriocidal drug
What is Trimethoprim-Sulfonamides used for?
Primarily in treatment of respiratory and urinary tract infections
What is the toxicity of Trimethoprim-Sulfonamides?
1. Relatively non-toxic
2. Especially effective for low does, long term therapy of urinary tract infections (SMZ/TMP; Tribrissen)
What things make an antibiotic effective?
1. Organism should be susceptible or sensitive to the drug
2. Drug must distribute to site of infection in adequate concentrations
3. Environmental conditions at site of infection (pH, abscesses, blood supply, etc)
4. THe patient must be considered (age, condition, economics, etc)
What are reasons for antibiotic failure?
1. Wrong drug
2. Wrong dosage
3. Wrong administration
4. Bacterial resistance