Antibiotic sensitivity testing

Laboratory testing measures whether microorganisms are inhibited or killed by particular antimicrobial drugs. Results help clinicians select treatments and monitor antimicrobial resistance.

Kirby–Bauer test: A disk-diffusion test that estimates bacterial susceptibility from growth-free zones around antibiotic disks. This widely used method measures inhibition zones on an inoculated agar plate.
Antimicrobial susceptibility: The degree to which a microorganism is inhibited by an antimicrobial agent at specified concentrations. Testing quantifies this underlying property rather than directly predicting every treatment outcome.
Antimicrobial stewardship: Coordinated efforts to use antimicrobial drugs appropriately and preserve their effectiveness. Susceptibility results can support narrowing or changing antimicrobial treatment.
Molecular antimicrobial resistance testing: Testing that detects genetic determinants associated with antimicrobial resistance. Genotype detection identifies resistance genes, while phenotypic testing measures actual growth response.
Broth microdilution: A method that tests serial antimicrobial concentrations in small liquid-culture wells to determine the minimum inhibitory concentration. It produces quantitative MIC results across a panel of drug concentrations.
Bacterial culture: The laboratory growth of bacteria in controlled conditions for identification or analysis. Susceptibility tests usually begin with a cultured isolate.
Empiric therapy: Treatment started before the causative pathogen and its drug susceptibility are fully known. Testing can replace an initial broad guess with isolate-specific evidence.
Antibiotic allergy testing: Clinical testing that evaluates whether a person has an immune-mediated allergy to an antibiotic. It concerns patient reactions, not whether a microorganism responds to a drug.
Minimum bactericidal concentration: The lowest antimicrobial concentration that kills a specified proportion of the initial bacterial population. It distinguishes growth inhibition from bacterial killing when that distinction matters clinically.
Clinical breakpoint: A threshold that classifies an organism as susceptible, intermediate, or resistant using test results and clinical evidence. Breakpoints convert measured MICs or inhibition zones into treatment-relevant categories.

Linked from 59 pages