Audit of Positive Microbiological Cultures in Patients Undergoing Arterial Reconstruction

Objective

To describe the micro-organisms cultured in vascular patients and report the changing spectrum of pathogens over recent years.

Methods

Retrospective analysis of post-operative microbiology culture results from wound swabs, blood cultures, theatre specimens and central venous catheter tips for all patients undergoing vascular procedures between 1998 and 2003.

Results

460 patients underwent a major vascular procedure; suprainguinal bypass (n=34), infrainguinal bypass (n=158), carotid endarterectomy (n=97) and abdominal aortic aneurysm repair (n=171). Positive microbiology results were identified in 86 patients (18%). Patients admitted as emergency had a significantly higher (chi²=20.2, p<0.0001) proportion of positive cultures (29% vs. 13%).The proportion of positive cultures was significantly different between procedures; suprainguinal bypass 29%, infrainguinal bypass 27%, abdominal aortic aneurysm repair 19%, carotid endarterectomy 0% (chi²=33.9, p<0.0001). The most commonly isolated organisms were Methicilin-sensitive Staphylococcus aureus (26%), MRSA (19%), and Staphylococcus epidermidis (10%) accounting for infection in 78% of patients. The prevalence of positive cultures declined over the study period from 18% in 1998 (18%) to 9% in 2003. No cases of MRSA were identified before 1999, compared to 12 cases in 2000–2001 (8.5%) and 11 cases in 2002–2003 (7.1%). There was no significant relationship between positive culture status and in-hospital mortality.

Conclusion

Staphylococci were most common after vascular procedures and MRSA was cultured in a significant proportion. Antimicrobial chemoprophylaxis should aim to cover these organisms.

Keywords: Positive microbiological cultures, Staphylococcus aureus, Arterial reconstruction