Pseudo-outbreak of Mycobacterium fortuitum due to contaminated ice machines

Background. An almost 4-fold increase from normal baseline levels in the isolation of Mycobacterium fortuitum from respiratory tract specimens was observed. The majority of these isolates were obtained from patients residing on 1 of 2 wards, prompting an epidemiologic investigation. Methods. In addition to patient specimens, environmental cultures were collected from various water sources on the 2 affected wards Samples were also collected from uninvolved areas of the hospital. All specimens were cultured with use of a continuously monitored broth system for the isolation of mycobacteria. Results. The respiratory tracts of 19 patients were colonized by M. Fortuitum. Surveillance cultures obtained from uninvolved areas of the hospital were either negative for mycobacteria or were colonized by M avium complex or M gordonae. Two ice machines, servicing the affected areas each, were colonized by M fortuitum in multiple cultures. Conclusions. The M fortuitum pseudo-outbreak was due to contaminated ice machines located on each of the affected units. After removal and replacement of the ice machines, the pseudo-outbreak resolved.