In microisolation housing, sentinel bedding is sourced from which of the following relative to other cages in the room?

• A. Mixed bedding
• B. Fresh bedding from sterile supply
• C. No bedding
• D. Enriched bedding from sentinel cages only

Answer: (A)

In sentinel surveillance within microisolation housing, you want the sentinel animals to be exposed to the range of microbes present in the room, not just what’s in their own cage. That’s achieved by using mixed bedding—the soiled bedding collected from multiple cages in the room and placed into the sentinel cages. This composite bedding carries the variety of shed bacteria, viruses, and other organisms from the room’s population, giving the sentinels a representative exposure so health monitoring can detect agents circulating in that space.

Using fresh sterile bedding would prevent exposure to room pathogens and defeat the purpose of sentinel monitoring. No bedding would provide no exposure at all, and enriched bedding from sentinel cages only would bias results to just the sentinel’s own environment, missing agents present in other cages.