PMC8255223_01
Enhanced abdominal computed tomography (CT) (A, B) and multidetector computed tomographic angiography (C) findings showed a 27 x 32 mm sized saccular pseudoaneurysm (yellow arrows) with the surrounding inflammation, involving inferior mesenteric artery (red arrow) and left ureter (white arrow), in the left common iliac artery (A, C). The compression of the left ureter led to left hydronephrosis (yellow arrowheads) (B). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article).
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Abdominal computed tomography (CT) showed a 27 x 32 mm sized saccular pseudoaneurysm surrounded by inflammation in the left common iliac artery (Fig. 1; A, C). The inflammation affected the inferior mesenteric artery and the left ureter (Fig. 1A), which caused left hydronephrosis (Fig. 1B).
Microbiological findings.. Gram staining (x1000) revealed Gram-positive rods (yellow arrow) (A). The colonies showed a narrow zone of beta-hemolysis (B). E-test  (bioMerieux) showed penicillin, ampicillin, and sulfamethoxazole/trimethoprim to have minimum inhibitory concentrations (MICs) of 0.19, 0.125, and 0.064 mug/mL, respectively (C, D). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article).
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Gram staining showed Gram-positive rods (Fig. 2A), which were quickly and accurately identified as L. monocytogenes, using the matrix-assisted laser desorption ionization (MALDI) biotyper Sepsityper kit  (Bruker Daltonik GmbH, Bremen, Germany) with a high score value (2.03) and the Verigene  system (Luminex, Austin, Texas, USA), within 24 h of obtaining the blood cultures. Tokyo, Japan), following 24 h incubation at 5% CO2 and 37  C and exhibited a narrow zone of beta-hemolysis (Fig. 2B). I'Etoile, France) suggested minimum inhibitory concentrations (MICs) of 0.19, 0.125, and 0.064 mug/mL for penicillin, ampicillin, and sulfamethoxazole/trimethoprim, respectively, which indicated susceptibility, according to the Clinical and Laboratory Standards Institute (CLSI) document (M100-Ed30) (Fig. 2; C, D). There was no evidence of infective endocarditis, as evaluated by transthoracic and transesophageal echocardiography or bacterial meningitis, as observed from the cerebrospinal fluid examination on day 2. In addition, the stool culture obtained during admission was negative for L. monocytogenes.
Clinical course of the patient.. The patient was diagnosed with Listeria monocytogenes-infected aneurysm using the rapid diagnostic testing and the multidetector computed tomographic angiography finding, in addition to blood culture results within 24 h. Antibiotic therapy, using ampicillin was administrated on day 2 and blood pressure was well-controlled. There was no evidence of infective endocarditis or bacterial meningitis based on transthoracic and transesophageal echocardiography, and cerebrospinal fluid examination, respectively. Repeated blood cultures on day 6 tested negative for L. monocytogenes. In-situ Y-graft (Japan Lifeline Co.) placement with revascularization and omental implantation was performed on day 8. The isolate was consistent with L. monocytogenes serotype 4b, as determined using 16S rRNA gene sequencing and the GenBank Basic Local Alignment Search Tool (BLAST) analysis (www.ncbi.nlm.nih.gov/genbank/) (Identities 1441/1441, Gaps 0/1441, Score 2662bits). After three weeks of intravenous antibiotic therapy, the intravenous ampicillin was replaced with oral amoxicillin. Oral amoxicillin was discontinued on day 85 since all anastomoses remained patent without left hydronephrosis in the follow-up CT. The patient has remained disease-free without recurrence.
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Postoperative CT on day 16 indicated that all the anastomoses were patent without any complications (Fig. 3). Oral amoxicillin was discontinued on day 85, when all anastomoses remained patent without left hydronephrosis in the follow-up CT, and the patient has remained disease-free without recurrence (Fig. 3).