Helicobacter pylori is a common inhabitant of the hepatobiliary and gastrointestinal tracts of many animals. Epidemiologic studies have found that this organism is associated with cholesterol cholelithiasis, chronic cholecystitis, and gallbladder cancer in humans and animals. In a recent study, mice that were highly susceptible to gallstone diseases were either infected with various Helicobacter species or left as untreated controls. All mice were fed a lithogenic diet containing 15% dairy triglycerides, 1.0% cholesterol, and 0.5% cholic acid. Depending on the study protocol, mice were fed the diet for 8 or 18 weeks. Cholesterol gallstones developed in 80% of infected mice and in 10% of uninfected mice. The findings of this study show that enterohepatic Helicobacter species play an important role in the development of cholesterol gallstones in mice. The mechanism is unknown but it is possible that Helicobacter produce antigens or other soluble factors that affect or modulate enterohepatic cycling of conjugated bile acids.

Cholangitis is a common biliary disease in cats. There are two distinct types: (1) acute or chronic exudative cholangitis and (2) chronic persistent cholangitis characterized by lymphocytic inflammation (LC), which is similar to primary sclerosing cholangitis in humans. The cause of LC is unknown but it is assumed to result from immune-mediated factors. Cats with LC are often treated with prednisone as a palliative measure. In humans, Helicobacter has been found to be a major cause of chronic gastritis and peptic ulcer disease. In addition, there is increasing evidence that it may be associated with primary sclerosing cholangitis in people. In this study, bile from 15 cats with histologically confirmed LC was compared with 51 bile samples from unaffected cats. Polymerase chain reaction showed that 4 of 15 (26%) of samples from cats with LC were positive for Helicobacter species compared with only 8 of 51 (16%) of non-LC samples. This study was the first to detect H. pylori DNA sequences from the bile of a nonhuman species. Although the investigators found no significant difference between detection of H. pylori from cats with LC and normal cats, the authors concluded that H. pylori may be a cause of feline LC and may represent a reservoir of infection.

COMMENTARY: One of my favorite quotations is by the French philosopher-physician J.M. Charcot who wrote, "Disease is very old, nothing about it has changed, it is we who change as we learn to recognize that which was formerly imperceptible." The two papers abstracted above here, which suggest that Helicobacter species are involved with inflammatory liver disease in cats and with gallstones in mice, could not have been imagined even a few years ago. Modern microbiology has come a long way since agar plates and incubators. Polymerase chain reaction techniques are opening up completely new vistas in medicine. I wonder how many more "idiopathic" diseases will eventually be determined to have an infectious origin?

Identification of cholelithogenic enterohepatic Helicobacter species and their role in murine cholesterol gallstone formation. Maurer KJ, Ihrig MM, Rogers AB, et al. GASTROENTEROLOGY 128:1023-1033, 2005.

Detection of Helicobacter pylori in bile of cats. Boomkens SY, Kusters JG, Hoffman G, et al. IMMUNOL MEDICAL MICROBIOL 42:307-311, 2005.