Monitoring sentinel mice for Helicobacter hepaticus, H-rodentium, and H-bilis infection by use of polymerase chain reaction analysis and serologic testing

Background and Purpose: Natural infection of research mice with enterohepat ic Helicobacter spp. is common and may confound experimental studies from i ntercurrent disease. We evaluated a protocol of dirty bedding exposure for transmission of Helicobacter infection from colony mice to female Tac:(SW)f BR sentinel mice over 6 months. Methods: Cecal scrapings from culled colony mice and associated sentinel mi ce were tested for H. hepaticus, H. rodentium, and H. bilis using polymeras e chain reaction analysis (PCR). These results were correlated with the res ults of sentinel serum IgG responses measured by ELISA. Results: In 9 colony rooms, 43 of 45 mice were infected with H. hepaticus; in 14 rooms, 58 of 70 mice were infected with H. rodentium; and in 2 rooms, 2 of 10 mice were infected with H. bilis. Concurrence of Helicobacter infe ction between colony and sentinel mice was 82% for H. hepaticus, 88% for H. rodentium, and 94% for H. bilis. Concurrence of Helicobacter infection sta tus of sentinel cagemates was 98% for H. hepaticus, 86% for H. rodentium, a nd 95% for H. bilis. Fecal samples pooled by sentinel cage had positive PCR results for H. hepaticus and H. rodentium at 1 month in 60 and 44%, respec tively, of the cages that contained test-positive mice at necropsy (6 month s). By 3 months, detection rates were 100 and 81% for H. hepaticus and H. r odentium, respectively, and H. bilis was not detected until 4 months. Newly acquired infections with H. rodentium and H. bilis were evident throughout the 6-month study period. Seroconversion was coincident with positive PCR results in sentinel mice, and serum IgG values continued to increase until necropsy. The serum IgG; ELISA was 98 to 100% sensitive, but was low in spe cificity (34 to 44%), most likely attributable to common coinfection with H . hepaticus and H. rodentium. Conclusion: Sentinel mice acquire infection with Helicobacter spp. through dirty bedding exposure. Combined use of PCR analysis and serologic testing of sentinel mice was predictive of Helicobacter infection status of mouse c olonies used for biomedical research.