Methods: Nasal, rectal and pharyngeal swabs were performed before, during, and one month after the end of FQ treatment. Microbiological analysis will focus on 3 target bacterial species: Escherichia coli from the faecal flora, alpha-haemolytic streptococci from the pharyngeal flora and non-coagulase staphylococci in the nasal flora. Patients carrying resistance at day 0 in all three flora will be excluded. The incidence and risk-factors of the emergence of resistance to FQ will be assessed at the end of treatment by FQ and 1 month after the end of treatment. Patients having resistant bacteria in their flora at the end and/or after treatment will be compared with those with no resistance.