Emphysematous Aortitis due to Klebsiella Pneumoniae in a Patient With Poorly Controlled Diabetes Mellitus
On initial examination, his vital signs were within normal limits except for a blood pressure of 177/87 mm Hg. His physical examination demonstrated a nondistended abdomen with normal bowel sounds, mild lower quadrant tenderness on the left more than on the right, intermittent abdominal pain located around umbilicus with radiation to the back, and a negative psoas sign. His left medial foot had a nonhealing laceration with black sutures in place, with minimal erythema in the surrounding tissue and scab formation. He also had mild costovertebral tenderness on the left.
Initial laboratory investigation results were notable for a glucose level of 609 mg/dL and a white blood cell count of 14.6 × 103 cells/mcL with 86.5% of neutrophils. A CT scan of his abdomen revealed extensive atherosclerosis of the abdominal aorta and periaortic aneurysmal fluid collection with multiple foci of gas (Figure 1). Additionally, the aneurysmal fluid collection involved the proximal segment of the left common femoral artery, suspicious for left femoral arteritis (Figure 2). The patient was started on broad-spectrum antibiotics, morphine, and an insulin drip. Both urine and blood cultures were positive for K pneumoniae susceptible to multiple antibiotics. He was transferred to a tertiary medical center and was referred for a vascular surgery consultation.
The patient underwent surgical resection of the infected infrarenal EA and infected left common femoral artery with right axillary-bifemoral bypass with an 8-mm PTFE (polytetrafluoroethylene) graft. During the surgery, excision of the wall of the left common femoral artery and infrarenal aorta revealed frank pus with purulent fluid, which was sent to cytology for analysis and culture. His intraoperative cultures grew K pneumoniae sensitive to multiple antibiotics, including ceftriaxone, sulfamethoxazole/trimethoprim, and ampicillin/sulbactam. The vascular surgery team recommended inpatient admission and administration of 6 weeks of IV antibiotics postoperatively with ceftriaxone, followed by outpatient oral suppression therapy after discharge. The patient tolerated the surgery well and was discharged after 6 weeks of IV ceftriaxone followed by outpatient oral suppression therapy. However, the patient was transferred back to BPVAHS for continued care and rehabilitation placement.
The patient’s subsequent course was complicated by multiple hospital admissions, including aspiration pneumonia, hypoglycemia, diarrhea, and anemia. On one of his CT abdomen/pelvic examinations, a cysticlike mass was noted in the pancreatic head with a possible pancreatic duodenal fistula (this mass was not mentioned on the initial presurgical CT, although it can be seen in retrospect (Figure 3). Gastroenterology was consulted.
An upper endoscopy was performed that confirmed the fistula at the second portion of the duodenum. Findings from an endoscopic ultrasonography performed at an outside institution were concerning for a main duct intraductal papillary mucinous neoplasm (IPMN) with fistula, with biopsy results pending.
Discussion
This case contributes to the evidence that poorly controlled T2DM can be a predisposing factor for multiple vascular complications, including the infection of the aortic wall with progression to EA. Klebsiella species are considered opportunistic, Gram-negative pathogens that may disseminate to other tissues, causing life-threatening infections, including pneumonia, UTIs, bacteremia, and sepsis.9K pneumoniae infections are particularly challenging in neonates, the elderly, and immunocompromised individuals.9 CT is sensitive and specific in the detection of this pathologic entity.1,3 In patients with a suspected infectious etiology, the presence of foci of gas on CT in solid organ tissues is usually associated with an anaerobic infection. Gas can also be produced by Gram-negative facultative anaerobes that can ferment glucose in necrotic tissues.9
Although any microorganism can infect the aorta, K pneumoniae cultured from the blood specimen, urine culture, and intraoperative specimens in our patient was responsible for the formed gas in the aortic wall. Occurrence of spontaneous gas by this microorganism is usually associated with conditions leading to either increased vulnerability to infections and/or enhanced bacterial virulence.9 Although a relationship between EA and T2DM has not been proved, it is well known that patients with T2DM have a defect in their host-defense mechanisms, making them more susceptible to infections such as EA. Furthermore, because patients with T2DM are prone to the development of Gram-negative sepsis, organisms such as K pneumoniae would tend to emerge. Patients with poorly controlled T2DM and the presence of an infectious source can be predisposed to infectious aortitis, eventually leading to a gas-forming infection of the aorta.5,7
