Melioidosis

Clinical History

This 38-years-old man was admitted with a one month history of fatigue, variable fever, polyuria and polydipsia. He had lost 7 kilograms in weight. No past medical history or prescribed medications. With the exception of several erythematous papules in the epigastric region examination was unremarkable.

Imaging Findings

Ultrasound abdomen demonstrated multiple abscesses in both the right and left lobes of the liver, in multiple segments.

CT chest, abdomen and pelvis was performed, which identified multiple cystic lesions of variable size in the right upper lobe, right middle lobe and left upper lobe (Fig. 1). No evidence of mediastinal lymphadenopathy. Within the liver, multiple cystic lesions were identified, ranging up to 7 cm in size. These had enhancing walls, with multiple septae, giving a 'honeycomb' appearance (Figs. 2, 3, 4). The appearances were consistent with multiple abscesses. In addition several smaller, less well defined cystic lesions were present within the spleen consistent with splenic abscesses (Fig. 5).

Discussion

Background

Melioidosis is an infectious disease caused by a Gram-negative bacterium, Burkholderia pseudomallei, found in wet soil and water. The main endemic regions are Southeast Asia and Northern Australia [1].

Burkholderia pseudomallei is normally found in soil and surface or 'standing' water so a history of contact with soil/standing water is usual. The vast majority of individuals who have contact with soil containing Burkholderia pseudomallei suffer no effect; however, those with co-existing disease, in particular diabetes mellitus, are more susceptible. It is transferred to humans through inhalation of contaminated dust or by direct contact between breached skin and contaminated soil. Other predisposing conditions include chronic renal failure, haematological disorders, alcoholism, those on immunosuppressive therapies and in Australia the regular consumption of kava [2].

Clinical Perspective

The manifestations of melioidosis can be broadly classified into six types: disseminated septic, non-septic disseminated, localised, transient bacteraemic, probable, and sub-clinical forms [3].

Burkholderia pseudomallei has a greater predisposition for certain organs, which may be single or multiple organ in nature. The lungs, liver, spleen, muscle, bone and prostate are the most commonly affected sites, with pulmonary involvement being most common of all. Presentation may be variable with everything from outright sepsis to latent infection with no clinical symptomatology.

Diagnosis is on the basis of clinical acumen, laboratory findings and imaging appearances. Few full proof laboratory tests are available to detect the antigens and antibodies to Burkholderia pseudomallei. Therefore cultures from the affected sites are ideally collected to isolate the organism, which often requires imaging guided aspiration, such as from focal liver or splenic lesions.

Imaging Perspective

In many respects the imaging findings are non-specific in all organ systems, with no described pathognomonic signs, although a 'honeycomb' in appearance to liver and splenic abscesses has been documented, as well illustrated in this case [4]. Appearances are similar to other infectious or inflammatory conditions or in some circumstances may mimic malignant pathology, such as focal liver lesions.

The detection of multiple, discrete abscesses in the visceral organs, especially the spleen, should raise the suspicion of this disease in parts of the world where it is endemic. Ultrasound of the abdomen is recommended in all patients presenting with septicemia or fever of unknown origin with CT for detailed delineation of the multisystem disease extent [5].

Outcome

In our patient blood cultures isolated Burkholderia pseudomallei. The patient was treated with our institution's approved antibiotic regime consisting of intravenous Co-Amoxiclav and Ceftazidime for four weeks followed by co-trimoxazole 960 mg twice daily for at least six months. Alternatively carbapenum for 4-6 monotherapy may be administered.

Antimicrobial therapy is the mainstay of therapy with a 3 phase approach recommended. Initial acute phase (Phase 1) treatment, subsequent eradication (Phase 2) therapy and post-exposure prophylaxis (Phase 0). Eradication therapy typically requires 3-6 months of therapy [6].

Take Home Message

- In a poorly controlled diabetic presenting with sepsis in endemic areas, always consider melioidosis.

- Melioidiosis is a multisystem disorder, but a splenic abscess should always prompt suspicion of this diagnosis.

Differential Diagnosis List

Final Diagnosis

Melioidosis: Multisystem infectious diseaseSecondary: Newly diagnosed diabetes mellitus

URL:	https://www.eurorad.org/case/9076
DOI:	10.1594/EURORAD/CASE.9076
ISSN:	1563-4086