Mycotic aneurysm of the abdominal aorta in a patient undergoing hemodialysis: an unusual complication of Staphylococcus aureus bacteremia

Ruptured infected aneurysm of the thoracic aorta associated with tunneled dialysis catheter-related methicillin-resistant Staphylococcus aureus bacteremia in a hemodialysis patient

Patients with an indwelling tunneled dialysis catheter (TDC) for hemodialysis access are at a high risk of developing methicillin-resistant Staphylococcus aureus (MRSA) infection. MRSA bacteremia complications rarely include infected aneurysm. Here, we report the first case of an infected thoracic aneurysm associated with TDC-related MRSA bacteremia. An 86-year-old Japanese male with a TDC for hemodialysis access developed TDC-related MRSA bacteremia. Intravenous vancomycin was initiated, and the TDC was removed on day 3. Despite removal of the catheter and initiation of vancomycin treatment, MRSA bacteremia persisted. Chest computed tomography (CT) showed no aneurysm; however, calcification of the thoracic aorta was detected on admission. The patient subsequently developed hemosputum. CT revealed a thoracic aneurysm, which turned out to be caused by MRSA bacteremia. The patient eventually died because of the rupture of the infected aneurysm, as confirmed by autopsy. This report demonstrates TDC management in a patient with TDC-related MRSA bacteremia and the importance of investigating a metastatic infection to a calcified artery if bacteremia persists.

Endovascular management of a mycotic group A streptococcal abdominal aortic dissection

Pyrexia of unknown origin can represent a great diagnostic difficulty to clinicians. We present a case of pyrexia with abdominal and back pain, in which blood cultures performed demonstrated group A haemolytic streptococcus. Having recently been abroad, the patient was investigated to find a source. CT scans performed subsequently demonstrated an inflammatory infrarenal abdominal aortic dissection. The patient was treated with intravenous antibiotics and underwent endovascular repair. This case details the unusual presentation of spontaneous abdominal aortic dissection and its management by endovascular means. Emphasis is placed on the often clandestine manner of presentation of this condition and the importance of awareness in the investigating clinician. This case presents a patient infected with group A haemolytic streptococcus, leading to aortitis and spontaneous dissection, previously unreported in the literature.

Staphylococcus aureus Bacteremia: Compliance with Standard Treatment, Long-term Outcome and Predictors of Relapse

The long-term outcome of compliance with standard treatment recommendations for Staphylococcus aureus bacteremia was assessed. Cases of S. aureus bacteremia at our institution over a 2-y period were reviewed and follow-up performed by review of subsequent admissions or contact with primary care physicians. We encountered 226 cases (age 64.7 +/- 15.8 y) and most (171/226, 75.7%) had no removable source. In-hospital mortality rate was 32.7% (74/226). Follow-up of 104/152 (68.4%) survivors (for 386.7 +/- 449.8 d) revealed 23.1% (24/104) relapses: recurrent bacteremia (n = 19), distant site (n = 3) and local recurrence (n = 2). Most relapses (21124; 87.5%) occurred within 90 d of therapy. Relapse rate was higher with vancomycin treatment (20148 vs. 4/56; p < 0.001), bacteremia for > or = 3 d (9/20 vs. 15/84; p = 0.001), and failure to remove the source (6/7 vs. 6/22; p = 0.006). Vancomycin effect was independent of oxacillin susceptibility. Treatment for less than the standard 2-week duration among 19 patients with short duration of bacteremia (< 3 d) did not increase relapse rate (1/19; 5.3%). Duration of bacteremia, vancomycin therapy and failure to remove the source were predictors of relapse. Prospective studies are needed to determine if S. aureus bacteremias of short duration can be treated for 2 weeks or less, and define the optimal duration for prolonged bacteremia when vancomycin is used.

Surgery of infrarenal inflammatory aneurysm of abdominal aorta infected with methicillin resistant Staphylococcus aureus in a patient undergoing haemodialysis

INTRODUCTION Inflammatory abdominal aortic aneurysm accounts for 5% to 10% of all cases of abdominal aortic aneurysm and differs from typical atherosclerotic abdominal aortic aneurysm in many important ways. Although both inflammatory and atherosclerotic abdominal aortic aneurysms most commonly affect the infrarenal portion of the abdominal aorta, patients with the inflammatory variant are younger and usually symptomatic, chiefly from back or abdominal pain. Unlike patients with atherosclerotic abdominal aortic aneurysm, most with the inflammatory variant have an elevated erythrocyte sedimentation rate or abnormalities of other serum inflammatory markers. Computed tomography and magnetic resonance imaging are both sensitive for demonstrating the cuff of soft tissue inflammation surrounding the aneurysm that is characteristic of inflammatory abdominal aortic aneurysm. Inflammatory abdominal aortic aneurysm can be primarily infected by degenaration of an infected artery (in less than 1% of cases), or can become secondary infected in the already existing aneurysm. Secondary infection of the pre-existing aneurysm has big influence on treatment choice, but is also rare. Clinically non-symptomatic infection, also known as bacterial collonisation, can be very frequent, regarding a greatly increased number of positive intraoperative findings (10-15%). Prolonged intravascular catheterization, vascular grafting, repeated punctures with large bore needles, and decreased immune defense mechanism make uraemic patients undergoing hemodialysis more likely to develop Staphylococcus aureus bacteraemia and its complications. CASE OUTLINE The case shows a gigantic inflammatory aneurysm of the abdominal aorta, localized infrarenally, which was solved successfully by resection of the aneurysm of the abdominal aorta, and interposition of Dacron tubular graft 22 mm. Bacterial examination of the aneurysmal sac was positive: methicillin-resistent Staphylococcus aureus was detected. CONCLUSION There were no postoperative complications, and the final outcome was fully satisfactory. Control CT scans after 3, 6 and 12 months were regular, with signs of regression fibrosis of the retroperitoneum.

Persistence in Staphylococcus aureus bacteremia: incidence, characteristics of patients and outcome

Staphylococcus aureus bacteremia often persists. The reasons for persistence and its outcome are poorly defined. We conducted a prospective-observational study among 245 consecutive S. aureus (MRSA: n=125; MSSA: n=120) bacteremias (>or=1 positive blood cultures (BC)) among 234 adults (18-103-y-old; median=59 y) hospitalized during 1 January 2002-31 December 2002 at a 600-bed teaching hospital. Measurements included bacteremia duration, complication-rate (metastatic infection, relapse or attributable mortality) and outcome. Bacteremia duration was measured based on follow-up BC among 193 patients and estimated based on symptoms resolution in the rest. Measured (1-59 d; median=2) and estimated (median=1 d) duration correlated (r=0.885) though positive follow-up BC was often detected without fever (57/105 patients, 54.3%). Persistence (defined as bacteremia for >or=3 d) was noted in 84 cases (38.4%). Complication-rate increased steadily with bacteremia duration (6.6%, 24.0% and 37.7% in bacteremia for 1-2, 3 and >or=4 d, respectively; p=0.05). Cox regression analysis revealed that bacteremia duration correlated positively with endovascular sources (p=0.006), vancomycin treatment (p=0.016), cardiovascular prosthesis (p=0.025), metastatic infections (p=0.025) and diabetes (p=0.038). It is concluded that persistent bacteremia is a feature of S. aureus infection, irrespective of oxacillin susceptibility, associated with worse outcome. Risk factors include endovascular sources, cardiovascular prosthesis, metastatic infections, vancomycin treatment and diabetes. Patients at risk may benefit from novel treatment strategies.

Once bitten, twice shy: an unusual case report of a mycotic aortic aneurysm

Primary mycotic aneurysms of the aorta are a rare, but potentially lethal condition comprising less than 1% of all aortic aneurysms. All age groups are affected but patients younger than 50 years are most susceptible. Organisms commonly implicated in aortitis and mycotic aortic aneurysms include Salmonella species and Staphylococcus aureus(1). We present the first case report of a primary aortic mycotic aneurysm caused by Capnocytophaga canimorsus, a commensal organism found in the mouth of dogs and cats and occasionally associated with serious human infections.

Mycotic Common Iliac Artery Aneurysm Complicating Methicillin-Resistant Staphylococcus aureus Bacteremia: An Unusual Cause of Ureteric Obstruction

A 60-year-old man presented with ureteric obstruction secondary to a mycotic right common iliac artery aneurysm complicating methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. The diagnosis of MRSA was not known at the time of surgery, and in situ replacement of the aneurysm using a rifampicin-bonded prosthesis was performed. The patient made a full recovery, and to date there is no evidence of residual or recurrent infection. To our knowledge, this is the first reported case of mycotic iliac aneurysm infected with MRSA in the literature. We discuss the consequences and the considerable diagnostic and therapeutic problems that arise.

Coronary artery bypass graft mycotic aneurysms in a dialysis patient

Infection is a common problem in dialysis patients and ranks second behind cardiovascular disease as a major cause of death. The major causes of infections, mainly bloodstream infections, often are related to dialysis access. Metastatic infectious complications have been reported frequently in the course of such bacteremias. We report the case of a 79-year-old dialysis patient who was admitted with recurrent catheter-related bacteremia caused by methicillin-resistant Staphylococcus aureus. Echocardiography and a computed tomographic scan of her chest showed multiple coronary artery bypass graft mycotic aneurysms. Despite prompt dialysis catheter removal and antibiotic treatment, she had progressive deterioration of her hemodynamic and mental status and eventually died of profound sepsis. An autopsy confirmed computed tomographic findings, plus extensive suppuration involving the left atrial and ventricular myocardium and upper lobe of the left lung. To our knowledge, this is the first report of coronary artery graft aneurysms complicating infective endocarditis in a dialysis patient.

Acute aortic abnormalities

Aneurysm and type B dissections account for most acute abdominal aortic abnormalities. The postsurgical aorta deserves special attention owing to the risk of complications. Most aortic abnormalities presenting acutely are emergencies that carry a high risk of mortality, and imaging plays a critical role in patient evaluation. Modern helical CT scanners provide excellent spatial resolution, are readily available, and allow for rapid imaging. For these reasons, helical CT angiography is the imaging modality of choice for initial evaluation of the acute aorta.