Conditions · Infectious and tropical diseases

Melioidosis !

Melioidosis is a serious infection by a tropical soil and water bacterium. It causes pneumonia, abscesses and sepsis, mostly in people with diabetes.

Updated 2026-11-01

Structures involved

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Microorganisms that cause it

Burkholderia cepacia complex and Burkholderia pseudomallei

Why it happens

What it is

An infection by Burkholderia pseudomallei, a Gram-negative bacillus living in soil and surface water in the tropics. It ranges from skin infection and pneumonia to abscesses in spleen, liver and prostate and fulminant sepsis, and can relapse or reactivate years later.

Who gets it

Highly endemic in Southeast Asia and northern Australia, and increasingly recognised in the Americas. Colombia reports cases acquired locally, on the Caribbean coast and in the Andean region, and is one of the South American countries with the most reports after Brazil. In a case series from Valledupar, most patients had diabetes and bacteraemic pneumonia was the main form. It is probably underdiagnosed because laboratories can misidentify the organism, and cases rise after heavy rains and floods.

Causes

Burkholderia pseudomallei, an environmental Gram-negative bacillus intrinsically resistant to many antibiotics
Infection through skin cuts in contact with soil or water, inhalation of dust or droplets, or ingestion
Incubation usually 1–3 weeks, but latent infection can activate months or years later

Risk factors

Diabetes mellitus, the strongest risk factor
Heavy alcohol use and chronic liver disease
Chronic kidney disease and chronic lung disease
Thalassaemia, cancer, corticosteroid use or other immunosuppression
Farming, rice cultivation or other work in wet soil; rainy season, floods and storms

Pathophysiology

The bacterium survives and multiplies inside phagocytes and epithelial cells and can spread directly from cell to cell, which helps it evade immune defences. From the entry site it reaches the blood and seeds organs, forming multiple small abscesses. Impaired neutrophil function in diabetes and alcohol use favours severe disease. Organisms can persist dormant for years, explaining late activation and relapse.

Classification

Pulmonary melioidosis: acute pneumonia or chronic cavitating disease resembling tuberculosis
Bacteraemic or septicaemic melioidosis, with or without a focus
Localized: skin ulcer or abscess, parotid abscess (children), prostatic, splenic, hepatic, bone or joint infection
Neurological melioidosis (encephalomyelitis, brain abscess), rare

Symptoms and signs

Fever, often high, with rigors
Cough, sputum and pleuritic chest pain in pneumonia
Weight loss and chronic cough in chronic forms resembling tuberculosis
Abdominal pain from splenic or liver abscesses; urinary symptoms with prostatic abscess
Skin ulcers, nodules or abscesses; bone or joint pain
Confusion, headache or seizures in neurological forms

Diagnosis

Clinical: Suspected in a person with diabetes or other risk factors, from or returning from an endemic area, who has pneumonia, sepsis or abscesses, especially after rains or contact with soil and water. Its varied picture leads to confusion with tuberculosis and other infections.
Tests: Culture of blood, sputum, pus, urine and throat swabs is the gold standard; the laboratory must be warned, because automated systems may misidentify it as other Burkholderia or Pseudomonas species. Confirmation by a reference laboratory and molecular methods is recommended. Serology is of limited value in endemic areas.
Imaging: Chest X-ray or CT for pneumonia and cavities; abdominal ultrasound or CT to look for splenic, liver and prostatic abscesses, which are routinely sought.

Differential diagnosis

Pulmonary tuberculosis
Other bacterial community-acquired pneumonia and sepsis
Typhoid fever
Pyogenic or amoebic liver abscess
Leptospirosis

Goal of treatment

Control the acute infection with intensive intravenous antibiotics, drain abscesses, then give prolonged oral eradication therapy to prevent relapse.

Treatment

Medical: Intensive phase: intravenous ceftazidime or a carbapenem (meropenem) for at least two weeks, longer for deep infection, bone or brain involvement.
Medical: Eradication phase: oral trimethoprim-sulfamethoxazole for several months; completing the whole course is essential to prevent relapse.
Procedure: Drainage of large abscesses, such as prostatic, liver or joint collections; splenic and small liver abscesses often resolve with antibiotics.
Follow-up: Glucose control in diabetes, repeat imaging of abscesses, follow-up for relapse, and notification so the laboratory confirms the isolate.

Complications

Septic shock and multiorgan failure
Multiple organ abscesses
Septic arthritis and osteomyelitis
Relapse after incomplete eradication therapy
High mortality in bacteraemic disease

Prognosis

Mortality is high, especially with bacteraemia and septic shock and where diagnosis is delayed, and falls with early appropriate antibiotics and intensive care. Relapse occurs in a minority, mostly when eradication therapy is short or incomplete.

Prevention

Waterproof boots and gloves for work in soil and water, especially for people with diabetes
Covering skin wounds and avoiding contact with floodwater
Drinking treated or boiled water in endemic areas

Test yourself

Think of the answer, then tap the question to see it.

Which bacterium causes melioidosis and where does it live?

Burkholderia pseudomallei, a Gram-negative bacillus found in soil and surface water in tropical regions.

What is the main risk factor for melioidosis?

Diabetes mellitus.

Which chronic infection can melioidosis mimic in the lungs?

Pulmonary tuberculosis, with cavitating upper-lobe disease and weight loss.

What are the two phases of melioidosis treatment?

An intensive intravenous phase (ceftazidime or a carbapenem) followed by months of oral eradication therapy (trimethoprim-sulfamethoxazole).

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: About Melioidosis | Melioidosis | CDC (Centers for Disease Control and Prevention, 2024); Case Series Study of Melioidosis, Colombia (Emerging Infectious Diseases (CDC), 2019).

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Representative model, for educational purposes only.

Spleen highlighted on the Durgical 3D model