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Using Filter Media and Soiled Bedding in Disposable Individually Ventilated Cages as a Refinement to Specific
Caroline B Winn1, Renee N Rogers2, Rose A Keenan2
1Pfizer Worldwide Research & Development, Comparative Medicine, Cambridge, Massachusetts;,
Abstract:
Molecular-based methods have shown potential for improving pathogen detection and reducing animal use. While increasing evidence supports rodent-free environmental health PCR pathogen detection, limited information is available regarding efficacy for disposable individually ventilated caging systems. In such systems, testing of plenum exhaust air dust is ineffective, and the use of collection media is optimal. We performed a series of studies to compare PCR infectious agent detection with dust collected on media placed in a mouse-free soiled bedding cage, the cage exhaust filter of an occupied sentinel cage, and direct sampling from colony and sentinel mice with traditional soiled bedding mouse sentinels. We hypothesized that after a 3-mo period, testing of filter media agitated in a soiled bedding cage would be equal to or more sensitive than more traditional methods. Agitated media detected Astrovirus-1, segmented filamentous bacteria and Helicobacter ganmani to a degree comparable to testing lid exhaust filter PCR from a sentinel mouse cage, but opportunists such as Staphylococcus aureus and Proteus mirabilis were not detected consistently, and H. hepaticus was not detected at all. Direct sampling of pooled fecal pellets and body swabs from sentinel mice and testing using PCR also failed to reliably detect opportunists and Helicobacter spp. While further work is needed to refine use of filter media in soiled bedding for detection of lower prevalence opportunists, this report provides evidence that a rodent-free method of reliably detecting murine agents in a disposable individually ventilated cage system with cage-level filtration outperforms direct sampling of soiled bedding sentinel mice.
Insights
Rodent-free pathogen detection using PCR in disposable individually ventilated cages shows promise. Filter media testing in soiled bedding cages is more effective than direct mouse sampling for detecting common murine pathogens.
Area of Science:
- Veterinary Microbiology
- Laboratory Animal Science
- Molecular Diagnostics
Background:
- Molecular methods offer improved pathogen detection and reduced animal use in research settings.
- Evidence supports rodent-free environmental health PCR pathogen detection, but efficacy in disposable individually ventilated caging (IVC) systems is less understood.
- Plenum exhaust air dust testing is ineffective in IVC systems; collection media is optimal.
Purpose of the Study:
- To compare PCR infectious agent detection using different methods in disposable IVC systems.
- To evaluate the efficacy of filter media collection compared to traditional sentinel mouse sampling.
- To determine the sensitivity of rodent-free methods for detecting common and opportunistic murine pathogens.
Main Methods:
- Collected dust on media from mouse-free soiled bedding cages and IVC exhaust filters.
- Compared PCR detection with samples from media, IVC exhaust filters, and direct sampling from sentinel mice.
- Assessed detection of specific agents including Astrovirus-1, segmented filamentous bacteria, Helicobacter ganmani, Staphylococcus aureus, Proteus mirabilis, and Helicobacter hepaticus.
Main Results:
- Agitated filter media detected Astrovirus-1, segmented filamentous bacteria, and H. ganmani comparably to sentinel mouse cage exhaust filters.
- Opportunistic pathogens like S. aureus and P. mirabilis were inconsistently detected on media; H. hepaticus was not detected.
- Direct sampling from sentinel mice failed to reliably detect opportunistic and Helicobacter species.
Conclusions:
- Rodent-free detection using filter media in soiled bedding cages shows potential for common murine pathogen surveillance in IVC systems.
- This method outperforms direct sampling from soiled bedding sentinel mice for detecting certain murine agents.
- Further refinement is needed for detecting lower-prevalence opportunistic pathogens using filter media.
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