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This case report highlights (i) The importance of ruling out infectious aortic aneurysm in a patient with rapidly expanding lung infiltrates with signs of sepsis and respiratory symptoms. (ii) The rare occurrence of fusobacterium bacteremia secondary to infected aneurysm.
A 59-year-old male with history of hypertension, presented with substernal chest pain, vomiting, fever and one episode of hemoptysis. Patient was admitted a week ago with similar pain and stress ECHO was negative for ischemia. He had presented to the ED (emergency department) 4 days ago, was diagnosed with pneumonia and was discharged on levofloxacin. The new onset of hemoptysis and the persistent symptoms prompted him to come to the ED again. He had a 10 pack year smoking history, consumed alcohol every day and used marijuana. He was tachycardic, but otherwise hemodynamically stable and was saturating well on room air. Lung exam noted decreased breath sounds in the left anterior lung. He did not have any further episodes of hemoptysis. Labs revealed hemoglobin of 9.6g/dl (baseline of around 12g/dl), leukocytosis of 18.5 × 103/mm3 and acute kidney injury with blood urea nitrogen of 53mg/dl and creatinine of 4.92mg/dl. Chest X-ray showed interval increase in mass like border of the upper mediastinum compared with the previous X-ray. With the suspicion of aortic aneurysm, CT chest without contrast was done initially and showed a cavitating left upper lobe mass in contact with the aortic arch, likely necrotizing pneumonia (Figure 1a). He was diagnosed with severe sepsis secondary to pneumonia, blood cultures were drawn and was started on intravenous vancomycin and piperacillin/tazobactam. With the continuing concern for aortic pathology, CT angiogram of thorax was done despite the risk with contrast. It showed inflammatory/infectious process involving the proximal ascending aorta with a saccular aneurysm, indicating contained rupture of the thoracic aorta, with surrounding lung necrosis and gas formation (Figure 1b). Vascular surgery consult was done and he underwent emergent endovascular stent graft. Blood cultures were found to grow Fusobacterium mortiferum. Infectious diseases consult was done and antibiotic was switched to ampicillin/sulbactam. Patient remained hemodynamically stable and renal function recovered. Repeat blood cultures were negative. Patient was discharged on a total of 6 weeks of intravenous ertapenem from negative cultures and chronic suppression with penicillin, as the stent was inserted when the blood cultures were positive.
Risk factors for infected aortic aneurysm include systemic infection, impaired immunity states including alcoholism and preexisting aneurysm. Even though Staphylococcus and Salmonella species are the common organisms,1 case reports have observed anaerobic bacteria in the oral cavity as etiology.2 Patients present with fever, chest pain, hemoptysis and respiratory symptoms, which may be misdiagnosed as pneumonia, especially in patients with no history of aneurysm. In our patient, the source of infection was presumed to be oral cavity, given his poor dental hygiene and the risk of aspiration given his alcohol use.
Infected aneurysm is rarely seen in thoracic aorta and the mortality may be up to 85% without surgery.3 A 12-year study found that the hospital mortality rate with medical treatment alone was 57% and the rate was 28%, even in patients who underwent surgery.4 In our case, the rupture was contained within the lung parenchyma, which probably offered a better prognosis. In addition to surgical intervention, antimicrobial therapy is indicated for at least 6 weeks and chronic suppression may be required if the procedure was done during active infection.
Fusobacterium only accounts for 0.9% of patients with bacteremia. Studies have found mortality rates of up to 10% with fusobacterium bacteremia.5,6 Even though our patient grew this rare organism in cultures, he improved with antibiotics.
In conclusion, it is important to rule out aortic pathology if a patient presents with rapidly expanding infiltrates close to the mediastinum. Prompt diagnosis can improve mortality and morbidity by early surgical intervention.
Conflict of interest: None declared.