participating in the POLMICRO scheme sent five consecutive clinical isolates of S. aureus (one isolate ⁄ patient) (n = 1376) during a 3-month period in 1999–2000 to the CQCM. Data on susceptibility to antimicrobial agents (obtained by disk diffusion tests) and additional information (e.g., hospital or ambulatory care, type of ward, site of infection) were collected.