In vitro analysis of gallstone formation in the presence of bacteria

In our previous study, we have isolated different genera of bacteria from gallstones and this intrigued us to study their role in gallstone formation. The isolates exhibited certain biliary activities like urease activity, slime production, and β-glucuronidase production. We aimed to investigate the role of these factors in the formation of gallstone in in vitro conditions at a supersaturated concentration of cholesterol.

To mimic bile in in vitro state, Brilliant Green Bile Broth (BGBB) media having a composition similar to human bile was used. Four different experimental sets were prepared, each having nine flasks with varying concentrations of cholesterol and CaCO3 (calcium carbonate). Test sets I, II, III, and IV were inoculated with Salmonella, Enterococcus, Helicobacter, and Neisseria respectively, which were isolated from gallstone itself. Out of these four bacteria, only Helicobacter did not possess slime activity. A control set was also established which was devoid of bacteria. The control also had nine flasks with different concentrations of cholesterol and CaCO3. All the sets were incubated in the incubator shaker at 37 °C and 80 revolution per minutes (RPM) for 20 days.

It was observed that the sets having bacteria had a less nucleation time as compared to the control (F = 5.274; p < 0.001). Solidification of gallstone was observed only in the set with bacteria having slime activity (sets I, II, and IV).

The slime activity of bacteria leads to solidification of gallstones, whereas the other activities accelerate the nucleation of gallstone formation enhancing the severity of the disease.