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Bacterial DNA in mixed cholesterol gallstones
1Department of Medicine, VA Medical Center, Seattle, Washington 98108-1597, USA.
The American Journal of Gastroenterology
|December 22, 1999
Summary
Bacterial DNA is commonly found in most gallstone types, except for pure cholesterol stones. This suggests bacteria play a significant role in the formation of common gallstones.
Area of Science:
- Gastroenterology
- Microbiology
- Biochemistry
Background:
- Biliary lithogenesis, the formation of gallstones, is a complex process.
- The role of bacteria in gallstone formation has been previously investigated.
- This study explores the presence and type-specific frequency of bacterial DNA in gallstones.
Purpose of the Study:
- To investigate the hypothesis that bacterial DNA is present in gallstones.
- To determine if gallstone type correlates with the frequency of bacterial DNA sequences.
- To identify specific bacterial species associated with gallstone formation.
Main Methods:
- Gallstones were categorized into types: brown pigment, common bile duct, mixed cholesterol, and pure cholesterol.
- Polymerase chain reaction (PCR) was employed to amplify bacterial 16S rRNA and uidA genes.
- PCR products were sequenced to identify bacterial species and their genetic material.
Main Results:
- Bacterial DNA sequences, including Escherichia coli (E. coli) and Pseudomonas species, were detected in all brown pigment, common bile duct, and mixed cholesterol gallstones.
- Pure cholesterol gallstones showed a significantly lower prevalence of bacterial DNA (14%).
- Bacterial DNA was found throughout mixed cholesterol gallstones, from the center to the outer portions.
Conclusions:
- Bacterial DNA is frequently present in mixed cholesterol, brown pigment, and common bile duct gallstones, but rarely in pure cholesterol gallstones.
- The findings suggest the involvement of bacterial beta-glucuronidase, indicating active bacterial presence.
- Further research is warranted to elucidate the role of bacteria and their products in the formation of mixed cholesterol gallstones, which are the most common type.