Bacteriological and electron microscopy examination of brown pigment stones

Abstract

Bacteriological and morphological studies of 38 brown pigment common duct stones were performed. Stone cultures were positive for bacteria in 80.5% of those studied. Enterococci were the most common organisms that were isolated. Scanning electron microscopy showed the presence of bacteria in 84.2% of the stones. The bacteria were seen embedded within an amorphous matrix in alternating layers of flakelike crystals. Transmission electron microscopy showed the presence of gram-positive and gram-negative bacteria surrounded by a ruthenium red-stained exopolysaccharide material. Results of the bacteriological and morphological studies confirmed the close relationship between the presence of bacteria and the development of brown pigment stones.