Emergence of bacterial resistance to antibiotics, which is a major public health issue, appears to involve predominantly commensal flora. No data exists concerning risk factors for the carriage of fluoroquinolone resistant bacteria in the flora of hospitalised patients. We will conduct a prospective open study including all unselected patients hospitalised in medical wards of one hospital. Nasal, pharyngeal and rectal swabs will be performed upon admission as well as a review of potential risk factors, after patient's information and acceptance. Resistance testing aiming 3 pathogens (Staphylococcus, Streptococcus and E. coli) will be performed on all specimens, and a case control study will compare risk factors from the resistant and non-resistant groups, for each pathogen. A thousand patients should be included in a year's time. This work could help understand risk factors involved in the carriage of fluoroquinolone resistant pathogens, potentially responsible for invasive infections and inter-patient transmission of resistance. Limiting bacterial resistance and transmission is a goal that can be successfully undertaken only if resistance mechanisms, but also risk factors of acquiring resistant bacteria are better understood.