Hospital ice, ice machines, and water as sources of nontuberculous mycobacteria: Description of qualitative risk assessment models to determine host–Nontuberculous mycobacteria interplay

Abstract

Over the last 30 years, there have been at least 17 published reports of nontuberculous mycobacteria (NTMs) being isolated from hospital ice or ice-making machines. Of these, 12 were reports of pseudo-outbreaks, i.e., the nosocomial transmission of organism from hospital ice/ice machines to patients, resulting in patient colonization, but with no disease manifestations. In addition, there were five outbreaks that resulted in clinical disease/pathology associated with NTM organism. Eleven different species of NTMs have been associated with these reports, where over half (59%) of the species identified were Mycobacterium fortuitum (18%), Mycobacterium gordonae (14%), Mycobacterium mucogenicum (14%), and Mycobacterium porcinum (14%). Several of these reports clearly documented that ice machines had been properly maintained, cleaned, and serviced in accordance with the CDC guidelines yet became contaminated with NTM organisms. These reports frequently detail that after extensive cleaning/disinfection following the discovery of NTM organisms, ice machines remained contaminated with NTM organisms, highlighting the difficulty in eradicating these from ice machines, once contaminated. Several reports identified that the only remedy to the contamination problem was to replace the ice machine with a new machine. Two qualitative risk assessment models are presented for (i) patients exposed to contaminated ice machine but before NTM colonization/infection and (ii) patients already colonized with NTMs from ice machines. Therefore, to protect immunocompromised/immunosuppressed patients' safety, especially during surgical or respiratory procedures, ice should not be sourced from the ice machine but should be made from sterile water and stored safely and separately away from the ice machine.

Keywords

• cystic fibrosis
• ice
• ice machine
• mycobacterium
• nontuberculous mycobacteria
• water