Case Report: Burkholderia pseudomallei Infection with Sepsis and Aortic Pseudoaneurysm

ABSTRACT.

Burkholderia pseudomallei is a Gram-negative bacterium found predominantly in tropical and subtropical regions. A 49-year-old individual with type 2 diabetes in Hainan, China, with a 4-month history of intermittent fever and 20 days of chest-back pain was diagnosed with aortic pseudoaneurysm through a computerized tomography scan. Burkholderia pseudomallei was identified through bacteriological examination of the patient’s blood. The patient received supportive care, with management of hyperthermia, heart rate, blood pressure, and blood glucose levels. Intravenous meropenem and oral sulfamethoxazole were administered for anti-infection treatment. Within 10 days, the patient’s temperature normalized, vital signs stabilized, chest pain subsided, and blood cultures cleared. This case highlights the potential severity of B. pseudomallei infections, underscoring the critical role of appropriate antibiotics, supportive care, and long-term follow-up in ensuring comprehensive management and preventing further transmission.

INTRODUCTION

Melioidosis, caused by Burkholderia pseudomallei, is a significant health concern in tropical and subtropical areas, with an estimated 165,000 global cases and 89,000 deaths annually.¹ Melioidosis commonly manifests as pneumonia, although infections at other sites are also frequent, and a significant number of patients present with disseminated disease.² The case fatality rate varies depending on the clinical syndrome, with potential rates reaching up to 66% in patients with bacteremia.³ Mycotic aneurysms attributed to B. pseudomallei account for only 1–2% of cases.^4,5 Here, we report a rare instance of melioidosis presenting as sepsis and mycotic aneurysm in Hainan, China, underscoring the significant treatment challenges and epidemiological implications associated with this condition.

THE CASE

On March 28, 2023, a 49-year-old man from Hainan was admitted to the Second Affiliated Hospital of Hainan Medical University. He complained of a 4-month history of intermittent fever with chest-back pain for 20 days. The fever occurred at irregular intervals, typically lasting several days or more than 10 days, and often presented as low-grade fever between 38 and 38.5°C in the afternoon before resolving naturally. The sudden onset of chest-back pain, initially characterized by dull discomfort, could be partially alleviated by rest but worsened in the days leading up to his admission.

The patient, previously diagnosed with type 2 diabetes, showed normal skin and heart/lung signs. Apart from chest and back pain, no joint tenderness, localized pain or swelling, or cardiac murmurs were observed. However, the examination revealed an elevated heart rate of 105/minute and a respiratory rate of 29/minute, both above the normal ranges. The white blood cell (WBC) count was 10.11 × 10⁹/L (RR: 3.5 × 10⁹–9.5 × 10⁹/L) with 9.07 × 10⁹/L neutrophils (NEU, RR: 1.8 × 10⁹–6.3 × 10⁹/L), a hemoglobin (Hb) concentration of 69 g/L (RR: 130–175 g/L), and a procalcitonin (PCT) concentration of 0.43 ng/mL (RR: <0.05 ng/mL). Notably, the patient’s highly sensitive C-reactive protein (hs-CRP) level was significantly high, at 163.85 mg/L, indicating a severe infectious inflammatory response, well above the normal range of 0.2–4 mg/L. Additionally, the patient’s blood glucose concentration was 15.93 mmol/L, significantly higher than the normal range (Table 1). The computed tomography angiography (CTA) examination revealed a pseudoaneurysm on the aortic arch (Figure 1A). In addition, scattered inflammation in both lower lung lobes, bilateral renal lithiasis, pseudoaneurysm on the aortic arch descending part (Figure 1B), and abdominal aortic ulcer were detected by computed tomography scan (Figure 1C).

Table 1.

Abnormal results of routine admission laboratory testing on admission

Parameter	Recorded Value	Standard Value
White blood cell count	10.11 × 109/L	3.5 × 109–9.5 × 109/L
Neutrophils	9.07 × 109/L	1.8 × 109–6.3 × 109/L
Hemoglobin	69 g/L	130–175 g/L
Albumin	28.7 g/L	35–50 g/L
Procalcitonin	0.43 ng/mL	0–0.05 ng/mL
Highly sensitive C-reactive protein	163.85 mg/L	0.2–4 mg/L
Blood glucose	15.93 mmol/L	3.9–6.1 mmol/L
Sodium	128.0 mmol/L	135–145 mmol/L
pCO2	25.8 mm of Hg	32–45 mm of Hg

pCO₂ = partial pressure of carbon dioxide.

Figure 1.

Angiography and CT scanning revealed (A) Pseudoaneurysm on aortic arch descending part, (B) Descending aorta false aneurysms (up) and abdominal aortic ulcer(down), (C) Suspicious bacterial plugs.

The patient was initially advised to undergo cross-matching of red blood cell suspension and plasma, along with receiving rehydration support and treatment with esmolol to manage his elevated heart rate. Additionally, a thoracic endovascular aortic repair was recommended for the pseudoaneurysm but was declined by the patient’s family because of financial issues.

Upon admission, the patient consistently experienced recurrent high fevers, reaching 40–41°C. Additionally, on day 1, his heart rate spiked to 160/minute, indicative of sinus tachycardia. The urinary glucose level was measured at 14 (+++) mmol/L, and the partial pressure of CO₂ was 28.00 mm of Hg. Notably, the patient’s blood pressure (BP) declined to 70/35 mm of Hg and fluctuated within the range of 140–70/88–27 mm of Hg in 24 hours, signaling a serious state of sepsis and septic shock. Consequently, therapeutic actions taken on day 1 included the use of a thermostatic blanket and medications to address hyperthermia, administration of sulperazon for anti-infection, and infusion of esmolol to lower the HR, dopamine to increase the BP, and insulin to regulate blood glucose levels. On day 2, the patient’s hemoglobin levels decreased to 64 g/L without any indications of blood in the stool or significant pleural effusion. The concentration of hs-CRP was recorded at 220.58 mg/L, while the WBC count was 12.22 × 10⁹/L. Additionally, the blood glucose concentration was measured at 12.09 mmol/L, and the PCT concentration was 1.61 ng/L. In the entire blood sample, the hemoglobin content (cTHb) was 64 g/L, compared with 53 g/L in arterial blood gas analysis. Red blood cell transfusion and ongoing treatments were administered in response to the critical infection indicators.

On day 3, the temperature stayed below 38°C, the Hb was stable, but the BP fell to 67/47 mm of Hg. The hs-CRP levels rose sharply to 277.16 mg/L, and the WBC count increased to 12.80 × 10⁹/L with NEU at 96.3%. The PCT increased to 1.96 ng/L, whereas the cTHb improved to 77.00 g/L. To stabilize the circulation, norepinephrine was administered, resulting in BP ranging from 126–67/73–39 mm of Hg in 24 hours.

By day 4, the patient’s temperature peaked at 38.5°C, with similar highs maintained through days 5 and 6. The interleukin-6 concentration was measured at 42.50 pg/mL. Throughout the 24-hour period, the BP fluctuated within the range of 142–103/90–48 mm of Hg. The results of the ultrasonic cardiogram and thoracic ultrasound revealed a minor regurgitation of the tricuspid valve, along with slight effusion in the pericardium and bilateral thoracic cavities. Additionally, on day 5, declines in hs-CRP to 160.29 mg/L and WBC count to 11.77 × 10⁹/L, with NEU at 87.5% and PCT at 0.05 ng/L, indicated signs of recovery. Also, the concentration of cTHb increased to 85.00 g/L, while the blood glucose level decreased to 6.79 mmol/L. The results of the blood culture confirmed that the infection was caused by B. pseudomallei. Antibiotic susceptibility testing revealed that the isolate was sensitive to ceftazidime, imipenem, doxycycline, tetracycline, and trimethoprim/sulfamethoxazole. Thus, the antibiotic treatment was adjusted to include intravenous meropenem at 1 g every 8 hours and orally administered compound sulfamethoxazole tablets at 240 mg every 12 hours, with a suggested duration of 4 to 8 weeks.

On day 7, the patient’s temperature normalized, allowing the patient to leave the intensive care unit based on stable vitals and no chest pain. Subsequent ward test results indicated that the patient’s mental condition, temperature, and hemogram had all improved. The use of venous vasoactive drugs was then discontinued, while the antibiotic pulse treatment was continued. On day 10, the patient opted to continue treatment at a local hospital. The blood cultures taken on April 7, 2023, the day of discharge, returned negative on April 12, signifying clearance of the infection from the bloodstream. The whole treatment timeline for the patient in our case is summarized in Figure 2. In the latest follow-up, it was confirmed that the patient remained stable and adhered to the prescribed regimen of sulfamethoxazole taken twice daily after discharge. However, 2 months later, he independently discontinued the medication due to improvements in his health. Our hospital recently recommended a comprehensive examination, including aortic CTA, to monitor his current physical condition and plan his treatment, but due to financial constraints, the patient did not follow through.

Figure 2.

Timeline of the patient’s treatment process.

DISCUSSION

Burkholderia pseudomallei, the causative agent of melioidosis, has seen an increase in reported cases in tropical and subtropical regions, particularly in Southeast Asia and southern China.^6–8 Notably, Hainan Island in China has reported a high concentration of cases, with recent studies highlighting the clinical and epidemiological aspects of the disease in the region. There were approximately 20–30 confirmed cases of melioidosis at Hainan People’s Hospital during the 2010’s.⁸ Recently, Wu et al.⁶ conducted a retrospective examination of 159 bacteremic melioidosis patients in Hainan Province, China, while Fang et al.⁷ described the clinical and epidemiological characteristics of 170 melioidosis cases across three general hospitals in Hainan from 2002 to 2013. Given the increasing number of cases reported in Southern China, it is crucial for medical professionals and diagnostic laboratories to be vigilant for this condition and its varied clinical manifestations.

Patients typically present with symptoms such as neck pain, odynophagia, fever, and elevated CRP levels, all of which were observed in this case. Pneumonia and septicemia emerged as the most prevalent presentations, and diabetes was frequently observed as a predisposing factor.⁷ This case underscores melioidosis in a diabetic patient leading to sepsis and aortic pseudoaneurysm, highlighting the critical need for early diagnosis and treatment because of the potential for severe vascular complications.⁹ Pseudoaneurysms are common vascular abnormalities that represent the disruption of the continuity of the arterial wall, allowing blood to flow into the tissue and form a perfused sac surrounding the damaged artery with persistent communication with the arterial lumen.¹⁰ A 20-year northern Australian study of melioidosis found pseudoaneurysms to be rare, with only two patients having mycotic pseudoaneurysms.¹¹ However, it may not be rare in Hainan, being far more common than previously realized and occurring in up to 5.0% of the bacteremic cases reported by Wu et al.⁶

Mycotic aortic aneurysm due to melioidosis remains a challenging disease to manage. Delayed diagnosis or treatment can lead to severe complications, including deep tissue infection, esophageal or tracheal perforation, mediastinitis, and severe sepsis. Treatment guidelines recommend a course of parenteral antibiotics to effect cure and a prolonged course of oral therapy to minimize relapse, which occurs in approximately 4% of cases.¹² In our case, an intensive phase with intravenous meropenem followed by a prolonged eradication phase with oral sulfamethoxazole was used for antibiotic therapy, which is also the recommended therapeutic regimen in Australia.¹³ Our previous research also suggests that lytic phage therapy might be effective against B. pseudomallei.¹⁴ As for other serious bacterial infections, the overall mortality rate after treatment of melioidosis is often due to subsequent infections and macrovascular diseases, particularly in individuals with preexisting risk factors. Modifiable risk factors such as diabetes should be aggressively managed in these patients. The patient refused the surgery because of financial constraints in our case. However, surgical intervention to repair pseudoaneurysm is critical in reducing the mortality rate from this disease.

In conclusion, this case report demonstrates the potential of B. pseudomallei to cause sepsis and mycotic aneurysm in areas where the bacterium is endemic. It highlights the critical role of timely antibiotic therapy and comprehensive supportive care in managing acute symptoms of B. pseudomallei infection and preventing its spread. Continuous long-term follow-up is essential to monitor for potential relapse.