Susceptibility testing of biliary bacteria obtained before bile duct manipulation.

Over a 3 3/4-year period, bile culture and susceptibility studies were performed on 41 patients before any instrumentation or manipulation of the biliary tract for retained biliary stone extraction. At least one bile bacterium was identified in 90% of the patients examined. As many as seven organisms were identified in one patient. Of the organisms, 62% were Gram-negative aerobes, the most representative being Klebsiella pneumonia; 27% were Gram-positive aerobes, the Enterococcus grouping being the most representative. Nine percent of the isolates were anaerobic bacteria and 2% yeast. Fifteen percent of the patients developed signs of sepsis. Three of these patients had manipulation of their bile ducts with a choledochoscope and grew out positive blood cultures; all were treated successfully and recovered uneventfully. Susceptibility testing on all aerobic bacteria was performed, indicating 97% effective coverage of both Gram-positive and Gram-negative bacteria using synergistic antibiotics of ampicillin and an aminoglycoside. Even with 9% of the isolated bacteria being anaerobes, the effective coverage using the same two drug combinations was about 88%. Because of the relatively high percentage (15%) of patients developing signs and symptoms of sepsis, synergistic prophylactic antimicrobial therapy is recommended in patients who are debilitated, in instrumentation of obstructed bile ducts, or with choledoschoscopy.