TIME-DEPENDENT CHANGES IN THE CONCENTRATION AND TYPE OF BACTERIAL SEQUENCES FOUND IN CHOLESTEROL GALLSTONES

The role of bacteria in gallstone formation could not be conclusively evaluated until bacterial presence or absence in a stone was consisten tly shown. Cultural bacteriologic investigations at the time of cholec ystectomy, however, led to the assumption that cholesterol gallstones were free of bacteria, In this study, we used a culture independent, m olecular genetic approach to detect, quantify, and identify bacteria i n cholesterol gallstones from 100 patients at the time of cholecystect omy and 6 months following. Bacterial growth was recorded in the cultu re in 9 of 100 gallstones; bacterial DNA, however, was detected in 82 of 91 sterile gallstones. High concentrations corresponding to between 10(6) to 10(7) bacteria/g were detected in 11 stones and low concentr ations of 10(5) bacteria/g were detected in 71 sterile stones, The inf ection in stones with a positive bacterial culture was characterized b y the predominance of single bacterial sequence(s) of the bacteria cul tured. A similar predominance, indicating a recent infection, was foun d in sterile gallstones with low DNA concentrations, A high diversity of non-repeating bacterial sequences, possibly arising from previous o verlapping infections, was found in sterile gallstones with high conce ntrations of bacterial DNA. After 6 months concentrations of bacterial DNA fell significantly in all groups of gallstones. As bacterial DNA is quickly destroyed upon storage, but is nevertheless readily found i n most gallstones at the time of cholecystectomy, there must be a mech anism by which it is replenished, One such mechanism is the frequently reoccurring, possibly self-terminating infection and another one is t he permanent colonization of the gallstone with bacteria at low concen trations. Both can promote cholecystolithiasis.