Red Book - Antibiotics Flashcards
Mechanisms by which Abx work
1) inhibit cell wall synthesis (bacteria needs to have a cell wall)
2) Inhibit DNA synthesis/funcion
3) Inhibit tetrahydrofolate synthesis
4) Inhibit protein synthesis
How do Abx work?
Either BacterioSTATIC or BacterioCIDAL
Static - limit growth so immune system remove bacteria after
Cidal - cause cell death whilst host cells remain undamaged (mammals dont have cell walls)
Examples of Bacteriostatic drugs
Macrolides
Tetracycline
Trimethoprim
Sulphonamides
Examples of bacteriocidal drugs
Penicillins Cephalosporins Aminoglycosides Glycopeptides Rifampicin
What is Time Dependent Killing
Agents whose activity depends on the amount of time the serum drug concentraction is above the Minimum Inhibitory Concentration (MIC)
Regularly dosed to keep conc above MIC as much as possible
Can increase half life by adding drugs that reduce Abx elimination e.g probenecid
EG - b-lactams, erythromicin, clindamicin, linez, vanc
What is Concentration Dependent Killing
Agents activity correlates with PEAK concentration.
Higher doses are used with lower frequency
May lead to toxicitiy
Aminoglycosides toxicity relate to TISSUE ACCUMULATION (e.g the trough level) not the peak level
Factors influencing Abx choice
1) Site of infection and likely organisms
2) Severity of infection –> fulminant should use broad spec
3) Their allergies
4) Side effects and risk of c.diff
5) Interactions - drug and PK (e.g. BBB)
6) Likelihood of resistant organisms
Recent ABx
LOS in hosptial/ICU
Ward or other hospital
Screening
Local resistance patterns
Examples of drugs that inhibit cell wall synthesis
Penicillins
Cephalosporins
Glycopeptides (Vacn/Teic)
Polymixin E
Examples of DNA synthesis inhibtion
Metronidazole (a nitromidazole)
Rifamycin (rifampicin)
Quinolones (cipro)
Examples of THF inhibition
Trimethoprim
Sulphonamides - co-trimoxazole
Dapsone
Examples of protein synthesis inhibitors
Tetracycline
Aminoglycc - gent, amikacin
Chloramphenicol
Macrolides - eryth/clarith/azith
Clindamyin
Linezolid (a oxazolidinone)
Examples of gram positive cocci
Staph
Strep
a - haemolytic - St.pneumoniae/viridians
b - haem - group A - pyogenes
groub B - agalactiae
y - enterococci
Gram positive bacilli
Actinomyces Bacillus Clostridia Diptheria Listeria
Gram neg cocci
Neiseria
Moraxella
Gram neg bacilli
Every thing else not covered
