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. (Am J Infect Control 2002;30:184-6.)