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Assessment of bacterial contamination of drinking water provided to mice
Carrie Haist1, Joan Cadillac, Robert Dysko
1Unit for Laboratory Animal Science, University of Michigan School of Medicine, 1150 W. Medical Center Drive, Ann Arbor, MI 48109-0614, USA.
Abstract:
The objective of this study was to evaluate whether an 240-ml water bottle provided to individually housed mice would remain potable for a 2-week interval (based on absence of coliforms). The study used inbred C57BL/6 mice and CB6F1 x C3D2F1 hybrid mice. Test groups were assigned to minimize the variables of strain, caging type (non-ventilated static versus ventilated) and building location. A 3-cc sample of drinking water was removed aseptically from the bottles and vacuum-filtered using a 250-ml filter funnel with a 0.45-mum pore size. The membrane filter was removed using sterile forceps and placed on a blood agar plate for 10 min. The plate was streaked and incubated at 37 degrees C for 5 days. The plates were observed daily, and if growth had occurred, further testing was done to determine specific organisms. Of the 148 samples only 23 had any bacterial growth. Typical bacteria were unspeciated gram-positive bacilli and Staphylococcus, Micrococcus, Streptococcus, and Pantoea species. The absence of coliforms and low percentage of bacterial contamination suggest that drinking water will remain potable for 2 weeks when supplied to an individual mouse.
Insights
Mouse water bottles remain potable for two weeks, with minimal bacterial contamination and no coliforms detected. This study ensures safe drinking water for laboratory mice over extended periods.
Area of Science:
- Laboratory Animal Science
- Microbiology
- Animal Welfare
Background:
- Maintaining potable water is crucial for laboratory animal welfare and experimental integrity.
- Standard water bottle protocols require regular monitoring for contamination.
- The 2-week water potability for individually housed mice needs specific evaluation.
Purpose of the Study:
- To assess the potability of 240-ml water bottles for individually housed mice over a 2-week period.
- To determine the presence of coliforms as an indicator of water safety.
- To evaluate bacterial contamination levels in mouse drinking water.
Main Methods:
- Aseptic water sampling (3-cc) from 240-ml bottles used by individually housed mice.
- Vacuum filtration of water samples through 0.45-µm pore size filters.
- Incubation of filtered samples on blood agar at 37°C for 5 days, with daily observation and further testing if growth occurred.
Main Results:
- Out of 148 samples, only 23 showed bacterial growth.
- Identified bacteria included gram-positive bacilli, Staphylococcus, Micrococcus, Streptococcus, and Pantoea species.
- No coliforms were detected in any of the tested water samples.
Conclusions:
- Drinking water in 240-ml bottles remains potable for individually housed mice for 2 weeks.
- The low incidence of bacterial contamination and absence of coliforms support a 2-week water change interval.
- Findings support current animal care guidelines regarding water provision for laboratory mice.
