Evaluation of Direct Colony Sampling Compared with Sentinel-Free Soiled Bedding Testing for Murine Quarantine Programs.

Sentinel-free soiled bedding (SFSB) is a form of environmental health monitoring that is an efficient method for monitoring rodent colony health. In contrast to direct colony sampling (DCS), when using PCR testing, SFSB can detect both active and past infections and is a less invasive method, classifying it as refinement. In this study, we compared DCS and SFSB for quarantine health monitoring in terms of their effectiveness in detecting pathogens during a 14-day quarantine program. In addition, we performed a time and motion study to examine the time required for each sampling method. We hypothesized that SFSB testing for quarantine would exhibit a greater degree of sensitivity than DCS for the tested pathogen list and take less time to perform. Eleven shipping containers, each containing 4-5 male or female mice aged 6-11 weeks, were subjected to simulated shipping stress as would occur during importation. During the 14-day quarantine, DCS samples included oral swabs, adhesive pelt swabs, and fresh fecal pellets that were pooled per cage and collected on days 0 (baseline) and 7. Each cage was given its own soiled-bedding sampling system, and SFSB samples were comprised of 3 groups: day 0, day 7, and a combination of days 0 and 7. There were no statistically significant differences between the 3 different SFSB sample time points (day 0, day 7, and days 0 and 7 combined) for all pathogens evaluated (P > 0.05). In addition, there were no statistically significant differences between the DCS day 7 and the days 0 and 7 combined SFSB time point for all pathogens evaluated (P > 0.05). Furthermore, SFSB was shown to be less time-consuming than DCS. Thus, SFSB sampling should be considered for quarantine health monitoring programs, as it has similar sensitivity to DCS, is a refinement, and offers a time-saving benefit.