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Significance of positive bacterial cultures from aortic aneurysm contents
Abstract:
Aneurysm contents were cultured in 275 patients out of a series of 546 cases undergoing infrarenal aortic aneurysm repair between 1961 and 1981. The incidence of positive cultures was 8 per cent. Cultures were more likely to be positive if taken from ruptured (16.7 per cent) and acute (9.1 per cent) aneurysms than from elective (4.2 per cent) cases (X2 = 6.69, P less than 0.01). Gram-positive organisms predominated with Micrococcus being the commonest isolate. Positive cultures were seen at an annual rate of 1-3 cases up to 1976 since which time all have been negative and we believe this may be due to prophylactic antibiotics being given preoperatively rather than postoperatively. The incidence of subsequent graft sepsis was greater in patients with positive aneurysm contents cultures (7 out of 22) than in those with negative cultures (6 out of 253) (X2 = 32.7, P less than 0.001). We recommend the routine culture of aneurysm contents to identify patients who are at high risk of developing graft sepsis and suggest that those cases with positive cultures receive prolonged organism-specific antibiotic therapy. In addition, there is evidence that pre-operative antibiotics may eliminate organisms from aneurysms, thus reducing the subsequent risk of graft sepsis.
Insights
Culturing aneurysm contents identifies patients at high risk for graft sepsis. Positive cultures, often Gram-positive bacteria, indicate a need for targeted antibiotic therapy to prevent complications after aortic aneurysm repair.
Area of Science:
- Vascular Surgery
- Microbiology
- Infectious Disease
Background:
- Aneurysm contents can harbor microorganisms, potentially leading to graft sepsis after surgical repair.
- The incidence and significance of positive aneurysm cultures in relation to graft infection remain areas of investigation.
Purpose of the Study:
- To determine the incidence of positive aneurysm cultures during infrarenal aortic aneurysm repair.
- To assess the correlation between positive cultures and the subsequent risk of graft sepsis.
- To evaluate the impact of prophylactic antibiotics on aneurysm culture positivity.
Main Methods:
- Aneurysm contents were cultured in 275 patients undergoing infrarenal aortic aneurysm repair between 1961 and 1981.
- Statistical analysis (chi-squared test) was used to compare culture positivity rates between different aneurysm types (ruptured, acute, elective) and to assess the association with graft sepsis.
- Organisms were identified, and their prevalence was noted.
Main Results:
- 8% of aneurysm cultures were positive, with higher rates in ruptured (16.7%) and acute (9.1%) aneurysms compared to elective (4.2%) cases.
- Gram-positive organisms predominated, with Micrococcus being the most common isolate.
- Patients with positive cultures had a significantly higher incidence of subsequent graft sepsis (7/22) compared to those with negative cultures (6/253).
- A decline in positive cultures after 1976 was observed, potentially linked to preoperative antibiotic use.
Conclusions:
- Routine culture of aneurysm contents is recommended to identify patients at high risk for graft sepsis.
- Positive cultures warrant prolonged, organism-specific antibiotic therapy.
- Preoperative antibiotics may reduce the incidence of positive aneurysm cultures and subsequent graft sepsis.