Incidence and significance of intra-operative bacterial cultures during abdominal aortic aneurysmectomy

Eighty patients undergoing abdominal aortic aneurysmectomy were studied to identify sources of potential graft sepsis. All but one patient received perioperative antibiotics. Samples obtained from aneurysm contents in 78 and bowel bag fluid in 45 were cultured for organisms. Twelve of 78 (15%) aneurysm cultures and five of 45 (11%) intestinal bag cultures yielded bacterial growth. Sixteen patients had positive cultures from either source and one from both, an overall incidence of 20%. Forty-four patients had asymptomatic aneurysms, 23 had symptomatic aneurysms, and 13 had ruptured aneurysms. A significantly greater frequency of bacterial growth occurred from ruptured than from non-ruptured aneurysms (p less than 0.05). Two patients (2.5%) developed graft sepsis. Comparing survivors followed a minimum of 6 months in the positive and negative culture groups, the late graft sepsis rate was 10% and 2% respectively. Two heretofore not widely recognized sources for late graft sepsis were identified: aneurysmal contents and intestinal bag fluid. Reasons for difference between potential graft sepsis incidence of 20% and actual incidence of 2.5% may include antibiotic therapy, host resistance, or other unidentified variables. Routine culture of aneurysm and intestinal bag contents is recommended. Upon identifying bacterial growth from such sources, organism-specific antibiotics are required.