Effectiveness of Various Floor Contamination Control Methods in Reducing Environmental Organic Load and Maintaining Colony Health in Rodent Facilities.

Floor contamination control practices in rodent housing facilities commonly include disposable shoe covers despite the lack of evidence for their usefulness in bioexclusion. Contamination control flooring mats are advertised as an economical and environmentally-responsible alternative to shoe covers, yet little is published regarding their efficacy in preventing the transfer of organic material and the introduction of infectious agents into facilities. We evaluated 4 floor contamination control strategies-shoe covers (ShCv), contamination control flooring (CCF), using both products concurrently (ShCv+CCF) compared with using neither-in preventing bacterial transfer and reducing organic load on facility floors and maintaining murine colony health status. According to PCR assay and culture analysis, ShCv provided the greatest reduction in bacte- rial numbers. Either ShCv, CCF, or ShCv+CCF significantly decreased ATP levels within the facility compared with those at facility entrances, with ShCv+CCF yielding the greatest reduction; however, even when neither ShCv nor CCF was used, intrafacility floor ATP levels were about half those at entrances. According to PCR analyses, no murine parasitic, viral, and bacterial pathogens excluded at the institution were detected in any floor, exhaust air dust, or sentinel samples at any time or location, regardless of the floor contamination control method in use. These findings show that floor contamination control methods help to reduce the organic load in rodent IVC facilities but do not enhance protection from environmental contamination due to murine pathogens.

Evaluation of Anthelmintic Resistance and Exhaust Air Dust PCR as a Diagnostic Tool in Mice Enzootically Infected with Aspiculuris tetraptera.

The entry of infectious agents in rodent colonies occurs despite robust sentinel monitoring programs, strict quarantine measures, and stringent biosecurity practices. In light of several outbreaks with Aspiculuris tetraptera in our facilities, we investigated the presence of anthelmintic resistance and the use of exhaust air dust (EAD) PCR for early detection of A. tetraptera infection. To determine anthelmintic resistance, C57BL/6, DBA/2, and NCr nude mice were experimentally inoculated with embryonated A. tetraptera ova harvested from enzootically infected mice, followed by treatment with 150 ppm fenbendazole in feed, 150 ppm fenbendazole plus 5 ppm piperazine in feed, or 2.1 mg/mL piperazine in water for 4 or 8 wk. Regardless of the mouse strain or treatment, no A. tetraptera were recovered at necropsy, indicating the lack of resistance in the worms to anthelmintic treatment. In addition, 10 of 12 DBA/2 positive-control mice cleared the A. tetraptera infection without treatment. To evaluate the feasibility of EAD PCR for A. tetraptera, 69 cages of breeder mice enzootically infected with A. tetraptera were housed on a Tecniplast IVC rack as a field study. On day 0, 56% to 58% of the cages on this rack tested positive for A. tetraptera by PCR and fecal centrifugation flotation (FCF). PCR from EAD swabs became positive for A. tetraptera DNA within 1 wk of placing the above cages on the rack. When these mice were treated with 150 ppm fenbendazole in feed, EAD PCR reverted to pinworm-negative after 1 mo of treatment and remained negative for an additional 8 wk. The ability of EAD PCR to detect few A. tetraptera positive mice was investigated by housing only 6 infected mice on another IVC rack as a field study. The EAD PCR from this rack was positive for A. tetraptera DNA within 1 wk of placing the positive mice on it. These findings demonstrate that fenbendazole is still an effective anthelmintic and that EAD PCR is a rapid, noninvasive assay that may be a useful diagnostic tool for antemortem detection of A. tetraptera infection, in conjunction with fecal PCR and FCF.