DTMH revision- Meliodosis

DTMH revision- Meliodosis

By AMIRAH amir

Multiple Select

Choose the correct statement regarding melioidosis.

• It is caused by Burkholderia mallei

• The agent is a gram negative aerobic bacteria

• Bipolar staining of the aetiological agent gives the so called

  ‘safety-pin’ appearance

• The most common form of melioidosis is pulmonary infection

Meliodosis

• Caused by the Gram-negative bacillus Burkholderia pseudomallei, found in contaminated water and soil

• Infections occur mainly in South East Asia and northern Australia.

• ‘Great mimicker’: presents with a wide spectrum of disease including isolated cutaneous/pulmonary disease, primary bacteraemia, visceral abscesses or fulminant fatal septicaemia.

• Risk factors: diabetes mellitus, hazardous alcohol use and chronic kidney disease. Less clearly defined independent risk factors include chronic lung disease, malignancy and systemic corticosteroid use​​

• Diagnosis: Culture (blood, urine and other sources which include joint fluid, sputum, cerebrospinal fluid, pus and tissue), Serology (not useful in endemic area. useful to monitor disease activities and relapse)

• CXR, Abdominal U/S, Abdominal/pelvic CT

• Treatment is difficult, and relapses are common.

• Initial treatment may be with intravenous ceftazidime (there are other regimens), followed by a combination of doxycycline and co-trimoxazole for 20 weeks.

• Despite adequate treatment, septicaemic meliodosis has a high mortality rate (up to 50%).​

Gram stain demonstrating “safety pin” appearance

Multiple Select

The following statements are true regarding epidemiology of melioidosis:

• It is common in tropical countries

• It is more common in males than females

• It is more common in children than adults

• A history of physical injury is common among patients with melioidosis

• Alcoholism is the commonest predisposing factor in most of the endemic countries

• Burkholderia pseudomallei is a common soil and fresh water saprophyte in tropical and subtropical regions.

• Melioidosis is a disease involving all age groups, commonly between 40 to 60 years and is related to farming. It is less common in the paediatric age group.

• More common in males. This may be due to more males being exposed in soil related occupations

• The postulated mode of infection (MOI) is direct entry of the organism into the blood stream via very minor wounds or skin abrasions. A definite history of injury is uncommon.

• The second commonest MOI is inhalation of contaminated dust.

• Other common MOI: drowning, MVA, via breast milk, perinatal transmission and human-to-human transmission

• In adults, diabetes mellitus is the commonest underlying disease

​

• Alcoholism and the consumption of kava (an extract of the root of the plant consumed by the Aboriginal people in Australia in place of alcohol) seem to be a major factor associated with melioidosis in Australia.​

​

• Other underlying diseases thought to be associated with melioidosis are chronic renal failure, renal calculi, chronic lung disease (especially cystic fibrosis in Australia), human immunodeficiency virus (HIV) infection, intravenous drug abuse, malignancy, systemic lupus erythematosus and corticosteroid therapy.

Multiple Select

The following statements on the clinical manifestation of melioidosis are true:

• Liver abscess is the commonest presentation

• Liver abscess is usually single

• Haemoptysis is common in patients with acute fulminant pneumonia

• Unilateral suppurative parotitis is the commonest form of localised melioidosis in adults

• Blood cultures are positive in 40% or more of cases

• Acute form: septicaemia and is associated with very high mortality​

• Chronic form: long-standing suppurative focal abscesses with fever and wasting and is associated with a good prognosis​

• ​In endemic areas, 88-90% of cases present with the acute form of melioidosis

• Pneumonia is the commonest clinical manifestation and is present in half of the cases (cough, fever) Haemoptysis is rare in acute disease but may be present in up to 31% of patients with the chronic form of the disease.

• Skin and subcutaneous involvement is the second commonest presentation

• Liver abscesses are frequently multiple (less likely to cause right upper quadrant pain and tenderness compared to other pyogenic abscesses)

• Localised infection is common in childhood, especially involving the head and neck region.

• Unilateral suppurative parotitis has been reported to account for 40% of localised melioidosis in Thailand

• Burkholderia pseudomallei can be cultured from blood in only a proportion of patients with melioidosis, as bacteremia is thought to occur in 40–60%, with other patients having localized disease. Blood culture has an estimated sensitivity of approximately 60% for melioidosis

Multiple Select

The following factors have been associated with an increased risk of relapse in melioidosis:

• Patients treated with ceftazidime during intensive therapy

• Patients with localised infection

• Patients treated with 8 weeks of maintenance therapy

• Diabetes mellitus

• Doxycycline monotherapy

Higher risk of relapse:

• septicaemia

• disseminated infection

• short course of maintenance therapy

• intensive therapy with antibiotics other than ceftazidime had higher risk of relapse

• poor adherence to the eradication therapy

• doxycycline monotherapy​

• Initial treatment should be with parenteral ceftazidime or a carbopenem for a minimum of 10 days.

• Several weeks of intravenous therapy may be needed to produce clinical improvement in patients with visceral abscesses.

• Oral maintenance therapy is required following completion of parenteral therapy to prevent relapse

• The combination of doxycycline and co-trimoxazole is cheap and effective if compliance can be maintained.

• 20 weeks’ therapy is advocated to reduce the relapse rate to less than 10%.

• Abscesses should be surgically drained when feasible.​

Multiple Select

The following factors are associated with a higher mortality in melioidosis:

• Bacteremia

• Presence of pneumonia

• A longer duration of fever

• Disseminated infection

• A low platelet count

Mortality due to melioidosis is extremely high especially in the bacteraemic form

​

Other possible factors associated with high mortality include

• a shorter duration of fever

• lower platelet count

• higher blood urea

• presence of pneumonia

• multi-organ involvement

• septicaemia of unknown source​

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