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Published on: November 5, 2019
Safety aspects of working with Candida albicans-infected mice
1Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK.
Abstract:
When the opportunity arose in the course of four experiments with mice and one with guinea pigs, all systemically infected with Candida albicans, the animals' bedding, work surfaces, surrounding walls, the balance pan and tools used in homogenization of tissues were sampled with contact plates or by water washing for the presence of viable C. albicans cells. Although substantial viable counts of C. albicans were measured in homogenized samples of kidneys and other tissues, no colonies of the fungus were recovered at any time from the work surfaces, walls or homogenizer stand. Contact samples of the homogenizer dispersal tool made on four occasions during the course of 24 successive homogenizations showed that few viable C. albicans could be cultured from the tool after two water washes, and none at all after two washes with 70% ethanol. Water samples of the contents of three cages that had housed infected mice were all negative for viable C. albicans, however, direct contact plate samples of the bedding material and excreta in seven cages yielded positive cultures with colony counts from 1 to 8 per sample in five instances and 18 in one instance. It is concluded that the potential infection risk to personnel of working with this hazard group 2 fungus is minimal and the highly stringent safety regulations for all organisms in hazard group 2 may err on the side of over-caution.
Insights
This study found minimal risk to personnel working with Candida albicans, a hazard group 2 fungus. Strict safety regulations for this fungus may be overly cautious, as contamination was primarily found in animal bedding and excreta, not surfaces.
Area of Science:
- Microbiology
- Infectious Diseases
- Occupational Safety
Background:
- Candida albicans is a common fungus and a recognized hazard group 2 organism.
- Systemic infections in animal models necessitate understanding potential environmental contamination and transmission routes.
Purpose of the Study:
- To assess the environmental contamination risk posed by Candida albicans in laboratory settings.
- To evaluate the effectiveness of cleaning protocols for laboratory equipment and surfaces.
- To determine the potential infection risk to personnel handling C. albicans.
Main Methods:
- Systemic infection of mice and guinea pigs with Candida albicans.
- Sampling of animal bedding, work surfaces, walls, balance pans, and homogenization tools using contact plates and water washing.
- Culturing and quantification of viable C. albicans from environmental samples and homogenized tissues.
- Testing the efficacy of water and ethanol washes in decontaminating homogenization tools.
Main Results:
- Substantial viable counts of C. albicans were found in homogenized animal tissues (kidneys).
- No C. albicans colonies were recovered from work surfaces, walls, or the homogenizer stand.
- Limited viable C. albicans were recovered from homogenization tools after washing; none after ethanol treatment.
- Positive cultures for C. albicans were obtained from animal bedding and excreta samples.
Conclusions:
- The environmental contamination risk from C. albicans in laboratory settings is minimal.
- Standard safety protocols for hazard group 2 organisms may be excessively stringent for C. albicans.
- Personnel infection risk when working with C. albicans is low, suggesting a need to re-evaluate current safety regulations.
