M9: CC2: Practical Aspects of Antibiotic Therapy Flashcards
What different types of antibiotic prescribing are there?
Prophylaxis is the use of _ agents to _
Types (4)
antimicrobial
prevent infection
perioperative
endocarditis
travel
opportunistic infection
What different types of antibiotic prescribing are there?
Perioperative prophylaxis is used to prevent _ infections
Clean wound:
No _ encountered
_, _, and _ not entered
Clean-contaminated wound:
_, _, or _ entered without significant _
Contaminated wound:
Gross spillage from _
Entrance into _ or _ with infected _ or _
Traumatic wounds or any wound with _
surgical site
inflammation
Respiratory, GI and GU tract
GI, GU or respiratory tracts
spillage
GI tract
GU or biliary tract, urine or bile
pus
What different types of antibiotic prescribing are there?
Endocarditis prophylaxis is used to prevent _ (infections of _) with procedures that induce _
Travel prophylaxis may be taken by travelers to prevent _
Opportunistic infection prophylaxis may be taken by _ patients to prevent infections such as _
endocarditis
heart valves
bacteremia
malaria
immunocompromised Pneumocystis jiroveci (carinii)
What different types of antibiotic prescribing are there?
Pre-emptive therapy is the use of antibiotics in case of an _ infection which is likely to become _ with serious consequences unless treated.
The treatment decision is mostly based on _.
ex. Starting _ in a transplant patient with evidence of _ reactivation by increased viral load per PCR in serum
asymptomatic
symptomatic
laboratory markers
valganciclovir
cytomegalovirus (CMV)
What different types of antibiotic prescribing are there?
Empiric therapy is the use of antibiotics for a _ infection but before the _ of the infection is known
Common infections for which empiric therapy is given include fever in _ patients, _-acquired pneumonia and _-associated pneumonia.
In general, delaying the antibiotic therapy until the microbiological diagnosis is made can be (beneficial / detrimental) to the patient in case of a rapidly progressing infection
The antibiotics chosen for empiric therapy depend on individual patient factors, exposures and local epidemiology
Empiric antibiotic therapy is by necessity “(broad / narrow)” in many instances
In some suspected infections it may be better to wait for _ or _ rather than give empiric antibiotics.
Many infections resolve due to the _ and do not justify the use of antibiotics.
presumed
etiology
neutropenic
community
ventilator
detrimental
broad
clinical progress or the results of cultures and susceptibilities
immune system of the host
What different types of antibiotic prescribing are there?
Pathogen-directed therapy is when the organism is _, but antibiotic susceptibility is _
Appropriate antibiotics can be selected based on the local _ of antimicrobial susceptibility, but are (broader / narrower) than when the susceptibility of the infecting organism is known.
known
awaited
epidemiology
broader
What different types of antibiotic prescribing are there?
Susceptibility-guided therapy is when the organism and the antibiotic susceptibility are both _
This allows for “_” of antibiotic therapy.
In general the antibiotic with the (broadest / narrowest) spectrum, the most _, least _ and _ is chosen.
known
streamlining
narrowest
effective
toxic
cheapest
On which occasions are no antibiotics required?
_ (for example, rhinitis) for which no effective antimicrobial medications exist.
_ (for example, one of two sets of blood cultures with coagulase-negative staphylococci)
_ (for example, the finding of vancomycin resistant Enterococcus faecium from a rectal swab)
_ (for example, bronchitis) even if bacteria are the cause.
Also, adequate _ obviates the need for antibiotics
Suspected viral infection
Contamination of the sample
Colonization in the absence of infection
Treatment has not shown to hasten the resolution of the infection
surgical drainage of an abscess
How do microbiology laboratories perform antibiotic susceptibility testing?
Disk diffusion:
Disks containing _ are placed on an agar plate and _ of bacterial growth is measured.
The greater the zone, the more _.
Method which determines the MIC? (y/n)
antibiotics
zone of inhibition
susceptible the bacteria are to the antibiotics diffused from the disk
n
How do microbiology laboratories perform antibiotic susceptibility testing?
Broth macrodilution, microdilution and agar dilution:
Test-tubes, microtiter plates or agar plates containing varying _ of the antibiotic are inoculated with the organism.
These are the classic methods for determining the _ of the antibiotic against that particular organism.
This is the lowest concentration of antibiotic at which there is _
Method which determines the MIC? (y/n)
concentrations
minimum inhibitory concentration (MIC)
no visible growth in the test-tube
y
How do microbiology laboratories perform antibiotic susceptibility testing?
E-test:
A _ is impregnated with different concentrations of antibiotics along its gradient.
The strip is placed directly on an _ inoculated with the organism.
The zone of inhibition can be read as the _
Method which determines the MIC? (y/n)
patented strip
agar plate
MIC
y
How do microbiology laboratories perform antibiotic susceptibility testing?
Commercial semi-automated methods:
These have a small number of _ containing varying concentrations of the antibiotic to be tested.
Usually only the concentrations around the “breakpoint” differentiating _ from _ organisms are tested.
Method which determines the MIC? (y/n)
wells
susceptible
resistant
n
How do microbiology laboratories perform antibiotic susceptibility testing?
Genetic testing:
PCR amplification can identify the presence of _ (rifampin resistant TB) or _ encoding enzymes conferring resistance to antimicrobials (HIV genotyping).
Method which determines the MIC? (y/n)
antimicrobial resistance genes
mutations in genes
n
What are some of the pharmacodynamic considerations in prescribing antibiotics?
2 types of antibiotics
concentration-dependent
time-dependent
What are some of the pharmacodynamic considerations in prescribing antibiotics?
Concentration-dependent antibiotics:
- Achieve maximal efficacy at _
- The upper concentration limit in the patient is limited by the concentrations that will produce _
(Examples include _ and _)
- Knowledge of the MIC is important because the ratio of _ to MIC is a predictor of efficacy of _
maximal concentrations
toxicity
aminoglycosides
fluoroquinolones
peak concentration
aminoglycosides
