Surgical Management of Ruptured Mycotic Aortic Aneurysm Induced by Klebsiella pneumoniae

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Surgical Management of Ruptured Mycotic Aortic Aneurysm Induced by Klebsiella pneumoniae

Mycotic aortic aneurysms (MAAs)—infected aortic bulges—are rare, accounting for less than 1% of all aortic aneurysms. Yet their rapid progression and high rupture risk make them life-threatening: without prompt treatment, survival rates are dismal. Recently, a team from The Catholic University of Korea shared a unique case of a ruptured MAA caused by Klebsiella pneumoniae—a bacteria rarely linked to this condition—and how they successfully treated it. Here’s what happened.

The Patient: A 63-Year-Old Man with Sudden Abdominal Pain

A 63-year-old man arrived at a local clinic with 1 day of severe, widespread abdominal pain. A CT scan revealed a ruptured abdominal aortic aneurysm (rAAA)—a dangerous bulge in the lower aorta that had burst. He had no history of high blood pressure, diabetes, or infections like hepatitis or pneumonia.

On exam, his blood pressure was low (100/70 mmHg), heart rate fast (105 bpm), and temperature slightly elevated (37.1°C). His abdomen was tender and swollen, with a pulsating 5×5 cm mass in the midsection. Lab tests showed mild anemia (hemoglobin 92 g/L) and elevated inflammation (C-reactive protein 10.24 mg/L)—clues that infection might be involved, though this wasn’t confirmed before surgery.

Emergency Surgery: Debridement, Graft Replacement, and Infection Control

Because the aneurysm had ruptured, the team performed emergency open surgery (the standard for ruptured aneurysms at their hospital). Here’s what they did:

  1. Access and Clamping: They made a midline abdominal incision to reach the ruptured aneurysm and surrounding blood clot. They clamped the aorta below the kidneys and both iliac arteries (the main leg arteries) to stop bleeding.
  2. Infection Discovery: Inside the aneurysm, they found significant infectious material—proof this was a mycotic (infected) aneurysm.
  3. Debridement: They removed all infected tissue, the aneurysm sac, and blood clots—critical to stopping the spread of infection.
  4. Graft Placement: They replaced the damaged aorta with a bifurcated polytetrafluoroethylene (PTFE) graft (a synthetic tube) connecting the aorta to both iliac arteries. To reduce graft infection risk, they covered the graft with an omental flap—fatty tissue from the abdomen that helps heal and protect the area.

Lab Results: Klebsiella pneumoniae as the Culprit

Tests on the infected tissue, blood clot, and aneurysm wall revealed a heavy growth of Klebsiella pneumoniae—a Gram-negative bacteria rarely associated with MAAs. The bacteria was sensitive to most antibiotics except ampicillin.

The team followed their protocol:

  • Pre-op/Post-op Antibiotics: They started third-generation cephalosporins (a strong antibiotic class) before surgery and continued IV doses for 4 weeks. They added metronidazole for the first 5 days to cover other bacteria.
  • Oral Antibiotics: After 4 weeks, the patient switched to oral cephalosporins for 2 more weeks (total 6 weeks of treatment—recommended for MAA to prevent recurrence).

Follow-up tests were clean: A blood culture at 3 weeks was negative, and a 6-month CT scan showed the PTFE graft was open (patent) with no sign of infection. The patient recovered without complications.

Why This Case Matters: Rare Cause, Standard (But Tailored) Treatment

MAAs are most often caused by Staphylococcus aureus (worldwide) or Salmonella (East Asia). Klebsiella is a rare trigger—but its Gram-negative status makes it particularly virulent: it can invade healthy artery walls and cause early rupture.

The gold standard for MAA treatment is combining:

  1. Adequate Antibiotics: At least 6 weeks of therapy to kill remaining bacteria.
  2. Surgical Resection: Removing all infected tissue to prevent spread.
  3. Graft Replacement: Replacing the damaged aorta with a synthetic or biological graft.

In this case, the team couldn’t use a cryopreserved allograft (a frozen donor aorta, which has lower reinfection rates) because it wasn’t available. Instead, they relied on:

  • Extensive Debridement: Removing as much infected tissue as possible.
  • PTFE Graft: Their preferred synthetic graft for ruptured aneurysms, as it may have better long-term outcomes (less enlargement, lower reinfection) than Dacron.
  • Omental Flap: A simple way to protect the graft and promote healing.

Key Takeaways for Patients and Providers

  1. Early Diagnosis Saves Lives: MAAs progress fast—sudden abdominal pain, a pulsating mass, or elevated inflammation should trigger urgent testing (like CT scans).
  2. Prompt Surgery Is Critical: Ruptured MAAs require emergency open surgery (endovascular therapy—less invasive—is an option for non-infected cases if anatomy allows).
  3. Long Antibiotics Are Non-Negotiable: 6 weeks of antibiotics (IV + oral) are needed to prevent infection recurrence.

The team’s success—no post-op infection, a patent graft, and a healthy patient at 6 months—highlights that even rare MAAs can be treated effectively with a rigorous, patient-centered approach.

Sang Dong Kim, Jeong Kye Hwang, In Sung Moon, Sun Cheol Park
Department of Surgery, Division of Vascular and Transplant Surgery, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea

The patient provided written consent for the publication of their case and images.

References

  1. Luo Y, Zhu J, Dai X, et al. Endovascular treatment of primary mycotic aortic aneurysms: a 7-year single-center experience. J Int Med Res 2018;46:3903–3909. doi:10.1177/0300060518781651
  2. Guo Y, Bai Y, Yang C, et al. Mycotic aneurysm due to Salmonella species: clinical experiences and review of the literature. Braz J Med Biol Res 2018;51:e68641-9. doi:10.1590/1414-431X20186864
  3. Kim HH, Kim DJ, Joo HC. Outcomes of open repair of mycotic aortic aneurysms with in situ replacement. Korean J Thorac Cardiovasc Surg 2017;50:430–435. doi:10.5090/kjtcs.2017.50.6.430
  4. Park SC, Moon IS, Koh YB. Tuberculous pseudoaneurysm of the descending thoracic aorta. Ann Vasc Surg 2010;24:417.e11-13. doi:10.1016/j.avsg.2009.05.019
  5. Aoki C, Fukuda W, Kondo N, et al. Surgical management of mycotic aortic aneurysms. Ann Vasc Dis 2017;10:29–35. doi:10.3400/avd.oa.16-00117

Original study published in Chinese Medical Journal 2019;132(1):89–91. doi:10.1097/CM9.0000000000000021

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