The flashcards below were created by user Porky on FreezingBlue Flashcards.

  1. Why are gram +ve bacteria more susceptible to penicillins?
    Penicillins target the peptidoglycan in bacterial cell walls

    There is a large amount of peptidoglycan in the gram +ve wall so more target

    There is a very small amount of peptidoglycan in the gram -ve wall which is also surrounded by a membrane, so there is less target and a protective layer for the penicillins to get through
  2. Acid labile
    • Unstable in gastric acid
    • Can't give orally

    ↑ acidity, ↑ ionisation, ↓ absorption
  3. Basic
    ↓ acidity, ↓ ionisation, ↑ absorption

    Ion trapping in milk/udder, prostate, lung, foetus and sites of inflammation
  4. Renal Crystalluria
    • Urine solubility exceeded
    • Principally acetylated metabolites
    • Crystallisation greater in acidic urine
    • Alkalinisation of urine ↑elimination and ↓precipitation 

    • May be reduced by:
    • using longer acting compounds
    • using more potent drugs
    • using combinations of sulphonamides
  5. Sulphonamide/Diaminopyrimidine Combinations
    • Trimethoprim + sulphadoxine or sulphadiazine
    • (5:1)

    • Advantages:
    • synergistic + bactericidal 
    • sulphonamide can be used at 1/8 dose
    • resistance to combinations is low
  6. Florfenicol
    Cloramphenicol → thiamphenicol → florfenicol

    • Does NOT induce irreversible bone marrow aplasia in humans
    • Causes REVERSIBLE haematopoetic depression in animals
    • Rapidly absorbed after IM (give to calves every 48hrs)
    • Good systemic availability
    • Long t½
    • ↑Vd
    • Some metabolism, rest excreted unchanged in urine
    • Broad spectrum
Card Set
Antimicrobial basics in addition to drug tables
Show Answers