Occult Bacteraemia and Aortic Graft Infection: A Wolf in Sheep’s Clothing

We report a case of late-onset aortic prosthetic vascular graft infection. We stress the importance of maintaining a high index of suspicion for any patient presenting with fever on the background of in situ prosthetic material. We present the difficulties in managing these extremely complicated, often life and limb threatening infections and suggest that a multidisciplinary team approach, involving specialist centre referral, may be key to success. We highlight the difficulties in diagnosing late-onset PVGI, where presentation can be subacute with subtle signs and confusing microbiology. In this case the presentation was pyrexia of unknown origin with multiple positive blood cultures isolating a variety of gut-associated organisms; a wolf in sheep’s clothing. 1. Background Prosthetic vascular graft infection (PVGI) is a significant complication of arterial reconstructive surgery [1]. The incidence has been reported to vary from 1 percent to 6 percent [2], depending on the site of the graft (infrainguinal 2–5%, aortofemoral 1-2%, and aortic 1%). Although the relative risk of PVGI is low, the clinical consequences of an infected vascular graft can be catastrophic for the patient, with an associated operative morbidity of 40–70% (limb amputation rates of up to 70% for lower extremity grafts [3]) and a recognized mortality rate of 30–50% (up to 75% with intra-abdominal aortic grafts [4]). We describe an unusual presentation of late-onset aortic graft infection which stresses the importance of maintaining a high index of suspicion in any patient with unexplained fevers and underlying in situ prosthetic material. In management of this case we demonstrate effective clinical use of Daptomycin and highlight the need for national consensus guidelines to guide the management of these complex infections. 2. Case Report This 79-years-old gentleman was admitted from the Infectious Diseases clinic, in April 2011. He presented to the clinic with night sweats, intermittent fevers, rigors, lethargy, weight loss, poor appetite, and generalised arthralgias. He described a change in the bowel habit over the previous few months with constipation and mild abdominal discomfort. His C-reactive protein was 58. This was his fourth follow-up clinic appointment following a recent hospital discharge. His past medical history included the following: August 2010 admission for relapsed septic arthritis of a right native knee, joint fluid aspirated at that time isolated Pseudomonas aeruginosa and blood cultures repeatedly isolated Pseudomonas aeruginosa and Enterobacter; July 2010