This surveillance made possible an immediate check up for an appropriate use of guidelines, allowing an optimal usage of antimicrobial agents. It's interest at term is to document audits (yearly for example) to discuss the effectiveness of our guidelines and, if necessary, to make new therapeutic choices, proven to be effective after investigation for clinical and microbiological data. Our surveillance system can be easily investigated by the physicians. It consists in checking on a weekly sheet all the new antimicrobial therapy courses, with name of patient, age, cause of antimicrobial therapy and hospitalization, bacteria, antibiotics used, for infection, before superinfection, previous superinfection, prophylaxis. A shift in usage of antibiotics can be observed, with consequences in antimicrobial therapy and hospital hygiene.