[What must one know about microbiology for prescribing antibiotics?].

Antibiotics are usually prescribed for serious bacterial infections. The knowledge of ecological niche of each bacterium, mechanisms of action and resistance to antibiotics and the correct interpretation of a direct exam of microbiological samples are essential to improve the use of antibiotics. Finally, the update of the epidemiology of resistance is necessary to interpret the susceptibility tests and for the optimal use of empirical antibiotherapy.