Listeriosis Infection of an Abdominal Aortic Aneurysm in a Diabetic Patient
A 72-year-old male hospitalized at an outside facility 2 months ago with lower-left lobe pneumonia treated with moxifloxacin for 12 days, and continuing symptoms of malaise, loss of appetite and weight loss, was referred to the emergency department with a symptomatic 4.9 cm AAA on CT scanning causing severe continuous lower abdominal and back pain requiring opiates and recurrent fever, up to 38.5°C. The latter symptom had started 12 days ago, although it had subsided 3 days later after receiving ciprofloxacin. Past medical history included COPD, hypertension, hyperlipidaemia, diabetes mellitus, and hyperuricemia. He was on formoterol and tiotropium inhalers, valsartan/hydrochlorothiazide, barnidipine, moxonidine, ezetimibe/simvastatin, sitagliptin/metformin, and allopurinol. He was an ex-smoker, while his occupation was sheep and goat keeper and slaughterer and he reported to consume raw dairy products, including home-made cheese made from unpasteurized milk. On presentation, he was hemodynamically stable, afebrile, while a tender AAA was noted. Leukocytosis (WBC 16,650/mm3 with a left shift) and raised CRP (29 mg/ dL, reference value <0.8 mg/dL) were found. Blood cultures were negative. He underwent an abdominal CTA with contrast ([Figures and ]) with a 16 × MDCT scanner (Lightspeed 16, GE, Milwaukee, WI, USA). The nonenhanced scan revealed an infrarenal AAA with a maximum diameter of 4.9 cm, in the axial plane, aortic wall calcifications, some of them apparently discontinuous, and subtle periaortic fat stranding. The contrast-enhanced CT scan underwent multiplanar reformat using the maximum intensity projection (MIP) algorithm. The aortic wall was markedly irregular, with the presence of multiple contrast-filled saccular outpouchings. There was also evidence of periaortic soft-tissue attenuation mass and/or luminal thrombus. The abnormalities extended distally up to the level of the aortic bifurcation, and the proximal part of the right common iliac arteries. There was no evidence of contrast extravasation or hematoma in the retroperitoneal space. There was no evidence of gas in the region. The abdominal CT scan was otherwise unremarkable.\nBased on the clinical picture, the history of an infectious disease (pneumonia) and CT findings, an infected AAA was suspected. Our patient was started meropenem 1gr TID and vancomycin 1gr BID and underwent urgent AAA repair with typical aortobifemoral bypass grafting using a 16 × 8 mm bifurcated e-PTFE graft (Advanta SST, Atrium Medical Corp, Hudson, NH, USA). Operative findings included an infrarenal AAA extending to the aortic bifurcation. The right common iliac artery was pulseless. The left common iliac artery had a whitish color. The intestine was adhered densely on the aneurysm. A small amount of dirty fluid inside the luminal thrombus was sent for culture along with aneurysmal wall samples and thrombus material for common bacteria, mycobacterium, and Brucella pathogens. Periaortic tissue and aortic wall were sent for histological examination. A part of the presumably infected aneurysmal sac was excised. The culture of the dirty fluid was positive for Listeria monocytogenes, sensitive to ampicillin, penicillin, vancomycin, teicoplanin, erythromycin, chloramphenicol, and ofloxacin. Additionally, a multisensitive Staphylococcus epidermidis was isolated. Histology showed acute sac inflammation. Postoperative course was uneventful and on postoperative day 10, our patient was transferred to his regional hospital to complete a further 4-week course of intravenous antibiotics (meropenem 2gr TID and vancomycin 1gr BID) and an additional 4-week course of oral antibiotics (trimethoprime/sulfomethoxazole 800/160 mg BID) as an outpatient. Eleven months later our patient remains asymptomatic.