Biliary bacteria as an indicator of the risk of recurrence of choledocholithiasis after endoscopic sphincterotomy

Bacteria have been implicated in recurrent choledocholithiasis associated with endoscopic sphincterotomy (EST). This study was designed to clarify whether bacterial examination of bile provides information useful in predicting the risk of recurrence of choledocholithiasis in patients undergoing EST. Bacteria in bile collected via a duodenoscope before cholangiography were cultured. We compared bacterial isolates and quantity among 41 patients with choledocholithiasis (7 with and 34 without a history of recurrent choledocholithiasis) who had undergone EST more than 3 months previously and 13 control patients with no evidence of pancreatobiliary disease. The bile samples were cultured under aerobic and anaerobic conditions. The bacterial quantity was expressed as the mean logarithm of the number of colony forming units (CFU)/ml. Furthermore, cholescintigraphic studies of bile flow were performed with the use of (99 m)TC-HIDA to study the clinical implication of these variables. No bacteria were detected in 10 of the 13 patients in the control group. In the other three control patients the bacterial count was 2.2 log CFU/ml or less. The mean bacterial count was significantly higher in patients with recurrence than in those without recurrence. Cholescintigraphy revealed a trend toward a higher number of isolates and a higher bacterial count in bile in patients with delayed bile passage than in those with good passage. The results suggest that an increased number of biliary isolates and an increased bacterial count indicate decreased bile flow in patients with choledocholithiasis who are being followed up after EST. These variables may potentially serve as indicators of the risk of stone recurrence. Especially when the bacterial count is higher than 7.0 log CFU/ml, the risk of a decrease in bile flow and an increased stone recurrence would be possibly found.