deck_4135631-2 Flashcards
How does antibiotic selection differ for empiric vs directed/targeted therapy?
For directed therapy, since you know the organism and susceptibility, you can use a drug with a more narrow spectrum*also, for directed therapy the antibiotic is given for a pre-defined duration
Compare the duration of therapy for the 2 causes of meningitis…
Meningitis due to strep pneumoniae = treat for 10-14 daysmeningitis due to Niesseria meningitidis = 7 days
What are two types of therapies that can be employed for the use of antibiotics?
Prophylactic therapy and combination therapy
Define prophylactic therapy
antibiotics are give to PREVENT the development of infectionchoose therapy based on drug of choice for the most probably organism and susceptibility patterns of the regionadminister as long as the patient is at risk
Define Combination therapy (specifically…what are 3 things it can be used to do?)
- broaden bacterial coverage to all organisms causing infection2. decrease the emergence of resistance3. take advantage of synergy by using more than 1 antibiotic
What are two examples of prophylaxis (prevention) that were discussed in lecture?
peri-operative surgical prophylaxisendocarditis prophylaxis
Explain peri-operative surgical prophylaxis
wound infections can be caused by skin floraduring operations, antibiotics are given against skin flora to reduce wound infection
explain endocarditis prophylaxis
to prevent endocarditis, antibiotic is given against oral flora for dental proceduresapplies if person has a damaged or prosthetic heart valve or previous endocarditis
For both prophylaxis examples, what is the overall dosing regimen?
single dose given onlyno benefit from prolonged antibiotic use
What are the 3 possible effects from combination therapy?
synergyadditiveantagonism
Define synergy
the antimicrobial effect of the two drugs together is greater than the additive activity of each one separately(A + B) > A + B
Define additive
the antimicrobial activity of the drugs used together is equal to the sum of each one separately(A + B) = A + B
Define antagonism
the antimicrobial activity of the drug combo is less than what you would expect from the addition of each one(A + B)
Give an example of synergy
For enterococcal endocarditis:penicillins don’t kill enterococcus, but if you add gentomyacin (aminoglycoside) you get rapid killing
Compare and contrast bacteriostatic vs bactericidal (definitions)
Bacteriostatic = antibiotic INHIBITS bacterial growth, killing depends on host defense mechanisms (to “cure” the infection)Bactericidal = antibiotic KILLS bacteria, is less dependent on host defense mechanisms*note: he said to know whether classes are bacteriostatic or bactericidal
What are disadvantages of bacteriostatic antibiotics?
If host defenses are inadequate, organisms that were only partially inhibited could survive/replicate and give a recurrent infection upon stopping use of the antibiotic (or if serum conc of the antibiotic go below the MIC)
Give an example where host defenses won’t be sufficient to get ride of infection
Endocarditis = infection on a clot in a valvebecause there’s no blood supply to the clot, host defenses don’t reach it
What are examples of bacteriostatic antibiotics?
macrolides, ketolides, tetracyclines, glycylcylines, sulfonamides, clindamycin, Synercid, and linezolid*note: he said to know whether classes are bacteriostatic or bactericidal
When would you want to use a bactericidal antibiotic (overall)?
it’s preferable if the host immune system is compromised or doesn’t function well (ex: neutropenia or immunosuppresion)*remember: neutropenia = low neutrophil levels
Bactericidals are required for the treatment of…? (give 4 examples)
meningitis (host defenses aren’t effective in sub-arachnoid space)endocarditisosteomyelitisfebrile neutropenia
What are examples of bactericidal antibiotics?
penicillins, cephalosporins, carbanpenems, aztreonam, fluoroquinolones, aminoglycosides, vancomycin, daptomycin, Bactrim, and metronidazole*note: he said to know whether classes are bacteriostatic or bactericidal
What is plotted for a pk graph? pd graph? pk/pd graph?
PK graph = conc vs timePD graph = conc vs effect (aka dose response curve)PK/PD graph = effect vs time
What are two important PD parameters for antibiotics?
AUC/MICTime above MIC
What is PAE?
Post-antibiotic effectit’s the time it takes for the bacteria to re-grow once serum conc of antibiotic fall BELOW the MIC (is drug and organism specific!)ex: sometimes the organism starts to grow immediately but sometimes there’s a gap (the gap is the PAE)
