[Principles of antibiotic prophylaxis].

Antibiotic therapy aims to reduce the risk of bacterial infection in a given patient. It can be useful after exposure to a pathogen (invasive meningococcal infections, whooping cough, etc.), before or during surgery, after an infection to prevent recurrence, or in patients who are at a high risk of bacterial infection (most particularly in hematology). The more the targeted pathogenic agent is unique (making use of a narrow-spectrum antibiotic possible), the more exposure is limited in time, the more the disease is potentially serious, and the more the antibiotic is easy to use and well tolerated, the more the antibiotic will be relevant and effective.