How clean is your ice machine? Revealing microbial amplification and presence of opportunistic pathogens in hospital ice-water machines
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Published on: March 13, 2017
M Cazals1, E Bédard1, C Soucy2
1Civil, Geological and Mining Engineering Department, Polytechnique Montréal, Montreal, Canada.
Background:
Ice machines in healthcare facilities have been suspected and even linked to outbreaks and pseudo-outbreaks. Guidelines exist for maintenance of these devices but there is no clear independent infection control standard, and little is known about their microbial contamination.
Aim:
To evaluate the microbial contamination, amplification, and presence of opportunistic pathogens in ice-water machines in a healthcare facility.
Methods:
Concentrations of general microbial indicators (heterotrophic plate counts (HPC), total and intact cells), faecal indicators (enterococci) and opportunistic pathogens (Pseudomonas aeruginosa, non-tuberculous mycobacteria (NTM), Candida spp.) were measured in 36 ice-water machines on patient wards of a 772-bed hospital. Profile sampling was performed on five ice-water machines and adjacent faucets to identify sites of microbial proliferation.
Findings:
Candida spp. were found in half of ice-water samples while enterococci and P. aeruginosa were present in six and 11 drain inlets respectively. NTM were measured in all ice-water samples and 35 out of 36 biofilms. Pre-filters and ice machines are sites for additional amplification: NTM densities were on average 1.3 log10 higher in water of ice machine flushed 5 min compared to flushed adjacent tap water.
Conclusion:
Ice machine design needs to be adapted to reduce microbial proliferation. The absence of correlation between HPC densities (current microbial indicators) and NTM concentrations suggests a need for cleaning efficiency indicators better correlated with opportunistic pathogens. Cleaning and disinfection guidelines of ice machines in healthcare facilities need to be improved, especially when ice is given to the most vulnerable patients, and NTM may be an efficiency indicator.
Insights
Healthcare ice machines harbor opportunistic pathogens like non-tuberculous mycobacteria (NTM). Current cleaning guidelines are insufficient, necessitating improved disinfection protocols and ice machine design to protect vulnerable patients.
Area of Science:
- Microbiology
- Infection Control
- Healthcare Engineering
Background:
- Ice machines in healthcare settings are potential sources of microbial contamination and outbreaks.
- Existing maintenance guidelines lack independent infection control standards.
- Limited data exists on the microbial contamination of these devices.
Purpose of the Study:
- To assess microbial contamination, amplification, and the presence of opportunistic pathogens in hospital ice-water machines.
- To identify specific sites of microbial proliferation within ice machines and adjacent water sources.
Main Methods:
- Analyzed ice-water samples from 36 machines for general and fecal indicators, and opportunistic pathogens (Candida spp., Pseudomonas aeruginosa, non-tuberculous mycobacteria [NTM]).
- Conducted profile sampling on five machines and faucets to pinpoint microbial hotspots.
- Measured microbial concentrations including heterotrophic plate counts (HPC).
Main Results:
- Candida spp. detected in 50% of ice-water samples; enterococci and P. aeruginosa found in drain inlets.
- NTM were present in all ice-water samples and most biofilms.
- Ice machines and pre-filters amplify NTM, with densities significantly higher than in adjacent tap water.
Conclusions:
- Current ice machine designs facilitate microbial proliferation and require adaptation.
- Heterotrophic plate counts do not correlate well with NTM levels, indicating a need for better cleaning indicators.
- Improved cleaning, disinfection guidelines, and NTM monitoring are crucial for vulnerable patient populations.
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