In most reported cases of RGM infection, the source of contamination is difficult to identify.5 To our knowledge, this is the first report of M fortuitum breast infection related to the hospital environment. In this report, rep-PCR typing revealed that the M fortuitum clinical strain matched with the strain recovered from the shower used by the patient during the postoperative period in the hospital. This evidence strongly supports that the water supply was the source of infection. Although an alternate route could not be excluded, our data supported that the route of infection was the surgical site and that the patient acquired the pathogen during postoperative care.