Durchführung eines Antibiograms an einem bakteriellen Stamm.
The Basics - Antibiograms · The Basics - Antibiograms 0 Cumulative data regarding isolate...
Transcript of The Basics - Antibiograms · The Basics - Antibiograms 0 Cumulative data regarding isolate...
The Basics - Antibiograms0 Cumulative data regarding isolate susceptibility at a
specified time period
0 Often every 3, 6, or 12 months
0 Provides the % susceptible to the tested antibiotic
0 Example: Out of the 125 isolates of E. coli, 87% were susceptible to cefepime
0 Guides empiric prescribing for likely pathogens
0 Core element of hospital antibiotic stewardship programs
Antibiogram Limitations0 Not frequently separated by unit in the hospital0 Does not trend data0 Gives susceptibility but not MIC50 or MIC90
0 Susceptibility interpretation may vary depending on if utilizing breakpoints by FDA or CLSI
0 Not all mechanisms can be detected0 Inducible resistance
0 Does not take into consideration patient specific factors0 Surgery, immune system, inoculum size0 Does not give information about site of infection0 Bacterial killing at different concentrations or doses of
antibiotics
0 Depending on method used to eliminate repeat isolates, the percentage susceptible may vary
Reading an Antibiogram
Organism
# of isolates
% Susceptible
Not tested, reported, or does not cover
Susceptibility Testing
0 Methodology can affect the reported susceptibility
0 Semi-automated machines
0 Vitek®, Microscan®, Phoenix®
0 Main methodology in clinical practice0 Accuracy varies between system and organism/antimicrobial
combination
0 Others:
0 Microboth dilution 0 Rarely used in clinical practice, but considered the reference method
0 Etest0 Frequently gives ½ to 1 dilution higher MIC
0 Kirby-Bauer disk diffusion
Interpretation of Susceptibility
0 Determined by:0 Clinical, pharmacological (pharmacokinetic), microbiological,
and pharmacodynamic considerations
0 FDA – determined at time of FDA approval 0 May be changed later if new data is available 0 Typically what is utilized with semi-automated systems
0 CLSI – Clinical Laboratory Standards Institute0 Non-government agency0 More “clinical”
0 Utilizes pharmacokinetic and pharmacodynamic data to determine which MICs would be obtained with typical dosing
0 Preferred
Combination Antibiograms0 Determines which antimicrobial combinations would
provide the greatest efficacy against Gram-negative pathogen
0 Particularly if resistant to beta-lactam