Biliary microflora in patients undergoing cholecystectomy.

Background: The management of acute cholecystitis requires a sound knowledge of the biliary microflora.

Methods: Bile samples were taken for culture according to a standard routine during all cholecystectomies performed from April 2007 to February 2009 in the Department of Surgery at Enköping Hospital. The use of antibiotics within the 3-mo period before surgery, indication for surgery, prophylactic antibiotics, and post-operative complications were recorded prospectively.

Results: Altogether, 246 procedures were performed during the study period, of which 149 (62%) were done on women. The mean (±SD) age of the study subjects was 49±16 y. Bacterial growth was seen in cultures from 34 (14%) of the subjects. The mean age of subjects with positive cultures was 64 y and that of subjects with negative cultures was 47 y (p<0.001). Positive culture was seen in 16 (31%) of the 51 patients who underwent operations for acute cholecystitis, whereas positive cultures were obtained in 18 of 195 patients without acute cholecystitis (9%) (p<0.001). Resistance to ampicillin was recorded in three of 34 (9%) of the cultures with bacterial growth, to co-trimoxazole in one of the 34 (3%) cultures, to fluoroquinolones in one of the 34 (3%) cultures, and to cephalosporins in one of the 34 (3%) cultures. Resistance to piperacillin-tazobactam was not observed in any of the cultures. In multivariable logistic regression analysis, a positive culture was the only factor significantly associated with risk for post-operative infectious complications (p<0.05).

Discussion: Bacterial growth in the bile is observed more often in patients undergoing surgery for acute cholecystitis. The microflora of the bile is probably important for the outcome of surgery, but further studies are required for assessing the effectiveness of measures for preventing infectious post-operative complications.