antibiograma

An antibiograma, or antibiogram, is a summary of the in vitro susceptibility of bacterial isolates to a range of antimicrobial agents within a defined setting and period. It is used to guide empirical therapy, inform antimicrobial stewardship programs, and monitor trends in antimicrobial resistance at a hospital, regional, or national level.

Testing involves isolating a pathogen from a clinical specimen and exposing it to antimicrobial agents using standardized methods. Common approaches include disk diffusion (Kirby-Bauer), broth microdilution, and gradient diffusion (E-test). Results are interpreted against established breakpoints set by guidelines such as CLSI or EUCAST, classifying each agent as susceptible, intermediate, or resistant. Some tests report MIC values, the lowest concentration inhibiting growth.

Antibiograms can be hospital-wide summaries or organism- or infection-site specific. They are often presented as a table listing organisms and the proportion of isolates susceptible to various antibiotics, sometimes with interpretive warnings or dosing considerations. Clinicians use antibiograms to select empiric therapy before culture results are available and to adjust treatment as data accumulate.

Limitations include that in vitro susceptibility does not guarantee clinical success, and results depend on testing conditions, the patient population, and local resistance patterns. Data may be biased by specimen sources, selective testing, and time lags. Antibiograms should be updated regularly and interpreted alongside patient factors and local guidelines.