EVALUATION OF VARIOUS ORAL ANTIMICROBIAL FORMULATIONS FOR ERADICATIONOF HELICOBACTER-HEPATICUS

Helicobacter hepaticus colonizes the cecum and colon of several strain s of mice from a variety of commercial suppliers, persistently infects mice, causes chronic hepatitis, is linked to hepatic tumors in A/JCr mice, and has been associated with inflammatory bowel disease of athym ic and scid mice. For this reason, eradication of the organism from in fected mouse colonies is desirable. We recently reported that amoxicil lin or tetracycline-based triple therapy (amoxicillin or tetracycline in combination with metronidazole and bismuth) given by oral gavage 3 times daily for 2 weeks eradicated H. hepaticus in 8- to 10-week-old A /JCr mice, To establish a more convenient therapy regimen for eradicat ing H. hepaticus, we evaluated water and dietary administration of var ious antibiotic combinations in A/JCr and DBA/2 mice naturally infecte d with H. hepaticus. The A/JCr male mice received amoxicillin-based tr iple therapy in drinking water or by oral gavage, or received tetracyc line-based triple therapy in the drinking water. The DBA/2J female mic e received amoxicillin-based triple therapy in a specially formulated dietary wafer or by oral gavage, or received enrofloxacin in drinking water. All treatments were given for a a-week period. Control animals received no treatment. One month after treatment, H. hepaticus was rec overed from the liver, cecum, or colon of A/JCr control mice and mice receiving amoxicillin- or tetracycline-based triple therapy in drinkin g water but not in mice receiving amoxicillin-based triple therapy by oral gavage. Helicobacter hepaticus was not recovered from DBA/2J mice receiving amoxicillin-based triple therapy in dietary wafer or by ora l gavage but was recovered from control mice and 7 of 10 mice receivin g enrofloxacin in drinking water. Results indicate that amoxicillin-ba sed triple therapy administered in the diet or by oral gavage is effec tive in eradicating H. hepaticus. Antibiotics administered in the wate r, however, were not effective in eradicating the organism.