Melioidosis

Quick Answer

One-liner: Melioidosis is a severe tropical infection caused by Burkholderia pseudomallei endemic to northern Australia, presenting as pneumonia or septic shock with 10-50% mortality requiring ceftazidime or meropenem and prolonged TMP-SMX eradication therapy.

Melioidosis is the most important tropical infection in northern Australia, with incidence rates of 16.5-50 per 100,000 in the Top End. It disproportionately affects Aboriginal and Torres Strait Islander peoples (40-50% of cases) due to high rates of diabetes and environmental exposure during monsoon season. The disease ranges from localized skin abscess to fulminant necrotizing pneumonia and septic shock. Mortality is 10-14% overall but rises to 30-50% with septic shock. Emergency physicians must have a high index of suspicion, start appropriate antimicrobials early (NOT standard broad-spectrum therapy), and prepare for ICU-level resuscitation.

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ACEM Exam Focus

Primary Exam Relevance

• Microbiology: Burkholderia pseudomallei - Gram-negative bacillus, facultative intracellular pathogen, intrinsic antibiotic resistance mechanisms
• Pathology: Acute necrotizing inflammation, abscess formation, granulomatous response, propensity for metastatic seeding
• Pharmacology: Beta-lactam antibiotics (ceftazidime - anti-pseudomonal cephalosporin; meropenem - carbapenem), folate antagonists (TMP-SMX), mechanism of resistance

Fellowship Exam Relevance

• Written: Recognition of endemic presentation, appropriate antimicrobial selection, understanding of two-phase treatment, Aboriginal health disparities
• OSCE: Septic shock resuscitation with melioidosis, communication with Aboriginal family, retrieval coordination from remote area
• Key domains tested: Medical Expert (diagnosis and management), Communicator (cultural safety), Health Advocate (Indigenous health equity), Cultural Competence

High-Yield Points:

• Melioidosis should be considered in ANY febrile illness in endemic areas (northern Australia, Southeast Asia)
• Standard empiric sepsis therapy (piperacillin-tazobactam, ceftriaxone) does NOT cover melioidosis
• Diabetes + wet season exposure + pneumonia = melioidosis until proven otherwise
• Two-phase treatment is mandatory: intensive phase (IV 10-14 days minimum) + eradication phase (oral 3-6 months)
• Aboriginal populations have 5-10× higher incidence

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Key Points

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Epidemiology

Australian/NZ Specific

Endemic Zones:

• Northern Territory: Top End (Darwin, Katherine) - highest incidence globally
• Queensland: Far North Queensland (Cairns, Torres Strait Islands)
• Western Australia: Kimberley region, Pilbara
• Non-endemic: Southern Australia, New Zealand (imported cases only)

Indigenous Populations:

• Aboriginal and Torres Strait Islander peoples represent 40-50% of all melioidosis cases despite being 30% of Top End population
• Incidence in Aboriginal Australians: 103-283 per 100,000/year (5-10× higher than non-Aboriginal)
• Higher burden driven by:
  • Diabetes prevalence 3-4× higher
  • Chronic kidney disease prevalence 4-5× higher
  • Hazardous alcohol use more prevalent
  • Environmental/occupational exposure (land management, wet season activities)
  • Socioeconomic factors (housing, healthcare access)

Darwin Prospective Melioidosis Study (DPMS):

• 30-year observational study (1989-2019)
• 1,148 cases analyzed
• Mortality declined from 30% (1989-1999) to 8% (2014-2019) due to "Darwin Bundle" standardized care
• 55% bacteremic at presentation
• 18% required ICU admission

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Pathophysiology

Mechanism

Organism Characteristics:

• Burkholderia pseudomallei - Gram-negative bacillus, oxidase-positive
• Environmental saprophyte found in soil and water (rice paddies, surface water)
• Facultative intracellular pathogen - survives within macrophages and epithelial cells
• Forms biofilms, can persist dormant for years (latent melioidosis)

Routes of Infection:

1. Percutaneous inoculation (60-70%) - soil/water contamination of wounds, abrasions
2. Inhalation (20-30%) - aerosolization during heavy rainfall, cyclones, dust storms
3. Aspiration/Ingestion (5-10%) - contaminated water
4. Rare: Direct person-to-person, sexual transmission, vertical transmission

Host Defense Impairment:

• Diabetes mellitus: Neutrophil dysfunction, impaired chemotaxis, reduced bacterial killing
• Chronic kidney disease: Uremia impairs T-cell function
• Hazardous alcohol use: Aspiration risk, impaired mucosal immunity
• Immunosuppression: Corticosteroids, chemotherapy, biologics

Pathological Progression

Environmental exposure → Inoculation/inhalation → 
Local infection (skin, lung) → Bacteremia (40-60% of cases) → 
Hematogenous dissemination → Metastatic abscess formation 
(liver, spleen, prostate, kidney, brain, bone)

Tissue Response:

• Acute necrotizing inflammation with microabscess formation
• Granuloma formation (can mimic TB)
• Propensity for multi-organ seeding
• Chronic/latent infection can reactivate years later

Why It Matters Clinically

• Antibiotic resistance: Intrinsic efflux pumps and beta-lactamases render most antibiotics ineffective
• Intracellular survival: Requires prolonged therapy to eliminate intracellular organisms
• Metastatic seeding: Single-organ treatment insufficient - requires systemic therapy
• Relapse risk: Without 3-6 month eradication phase, relapse occurs in 10-25%

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Clinical Approach

Recognition

Consider melioidosis in ANY patient with:

• Residence/travel to endemic area (northern Australia, Southeast Asia) within past 3-12 months
• Fever + risk factors (diabetes, CKD, alcohol, immunosuppression)
• Wet season presentation (November-April in northern Australia)
• Aboriginal or Torres Strait Islander ethnicity + acute illness
• Pneumonia with rapid progression to cavitation/abscess formation
• Sepsis without clear source

Initial Assessment

Primary Survey (Septic/Shocked Patient)

• A: Patent airway; assess for depressed GCS (septic encephalopathy, neuromelioidosis)
• B: Respiratory rate often greater than 25/min; hypoxemia common; listen for crackles, bronchial breathing (pneumonia); CXR may show rapid cavitation
• C: Hypotension (septic shock 15-20% at presentation); warm vs cold shock; prolonged capillary refill; tachycardia 110-140 bpm
• D: GCS assessment - meningitis/encephalitis rare but devastating; focal neurology suggests brainstem abscess
• E: Skin examination for pustules, abscesses; hepatosplenomegaly (metastatic abscesses); joint swelling (septic arthritis)

History

Key Questions

Red Flag Symptoms

Examination

General Inspection

• Toxic appearance, febrile (38.5-40°C)
• Tachypneic, use of accessory muscles
• Jaundice (hepatic involvement)
• Cachexia (chronic/relapsed disease)

Specific Findings

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Investigations

Immediate (Resus Bay)

Standard ED Workup

Advanced/Specialist

Point-of-Care Ultrasound

Indications:

• Lung POCUS: Consolidation (tissue sign), pleural effusion (anechoic space), lung abscess (complex collection)
• Abdominal POCUS: Hepatic/splenic abscesses (hypoechoic lesions), free fluid (rare unless perforation)
• Soft tissue POCUS: Guide drainage of superficial abscesses

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Management

Immediate Management (First 10 minutes)

1. Oxygen therapy - target SpO₂ 92-96% (or 88-92% if COPD)
2. IV access (×2 large bore) + blood cultures BEFORE antibiotics
3. Fluid resuscitation - 500mL boluses Hartmann's/N.Saline to MAP ≥65 mmHg
4. EMPIRIC ANTIBIOTICS if septic/shocked - DO NOT WAIT for cultures:
   - Ceftazidime 2g IV stat (if suspected melioidosis in endemic area)
   - OR Meropenem 1g IV stat (preferred if septic shock or critically unwell)
   - ADD standard broad-spectrum cover if source uncertain
5. Senior ED + Infectious Diseases consult
6. Consider ICU referral if lactate greater than 4, SBP below 90 despite fluids, RR greater than 30

Resuscitation (Septic Shock)

Airway

• Early intubation if GCS ≤8, severe hypoxemia (PaO₂ below 60 mmHg on high-flow O₂), or inability to protect airway
• RSI with ketamine/rocuronium (ketamine maintains BP)

Breathing

• Mechanical ventilation: Lung-protective strategy (Vt 6-8 mL/kg IBW, Pplat below 30 cmH₂O)
• PEEP 5-10 cmH₂O to maintain oxygenation
• ARDS common complication - may require ECMO in refractory cases

Circulation

• Fluid resuscitation: 30 mL/kg crystalloid within 3 hours (Surviving Sepsis Campaign)
• Target MAP ≥65 mmHg
• Vasopressors if hypotensive despite fluids:
  • Noradrenaline first-line (0.05-2 mcg/kg/min)
  • Vasopressin 0.03 units/min if refractory
• Inotropes: Dobutamine if cardiac output low despite adequate filling

Medications

Intensive Phase (Intravenous)

Clinical Pearl:

• Meropenem vs ceftazidime: MERTH trial (PMID: 21880587) showed non-inferiority; meropenem preferred for critically ill
• Granulocyte colony-stimulating factor (G-CSF): Some evidence (PMID: 21880586) for adjunctive use in septic shock (filgrastim 300 mcg SC daily × 7-10 days)

Eradication Phase (Oral)

Important Notes:

• Without eradication phase, relapse rate 10-25%
• With adequate eradication, relapse below 5%
• Monitor FBC weekly × 4 weeks, then monthly (bone marrow suppression from TMP-SMX)
• Relapsed disease requires 6-12 months total therapy

Paediatric Dosing

Ongoing Management

Source Control:

• Drain large abscesses (greater than 5 cm) - percutaneous or surgical
• Prostatic abscesses rarely need drainage if below 5 cm and improving on antibiotics
• Splenic abscesses usually managed conservatively; splenectomy if failed medical therapy

Monitoring:

• Daily: Clinical status, vital signs, urine output, inflammatory markers (CRP, WCC)
• Weekly: FBC (leukopenia from ceftazidime/TMP-SMX), renal function, LFTs
• Serial imaging (CT) at 2-4 weeks to assess response if abscesses present

Response to Treatment:

• Fever typically settles within 5-10 days
• Persistent fever greater than 14 days: Consider abscess drainage, alternative diagnosis, relapse
• CRP should decline by 50% within 1 week

Definitive Care

ICU Indications:

• Septic shock requiring vasopressors
• Respiratory failure requiring mechanical ventilation
• Multi-organ dysfunction (AKI requiring RRT, DIC)

Infectious Diseases:

• All confirmed/suspected cases require ID consult
• Guide duration of intensive phase (10-14 days vs 4-8 weeks)
• Supervise eradication phase compliance

Surgical:

• Large abscesses requiring drainage (IR-guided or open)
• Necrotizing soft tissue infection
• Osteomyelitis/septic arthritis requiring debridement

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Disposition

Admission Criteria

ALL patients with suspected or confirmed melioidosis require admission:

• Initiate IV antibiotics (ceftazidime or meropenem)
• Blood cultures and imaging (CXR minimum, CT if indicated)
• Assessment for metastatic disease
• ID consult within 24 hours

ICU/HDU Criteria

• Septic shock (SBP below 90 mmHg, lactate greater than 4, requiring vasopressors)
• Severe pneumonia (PaO₂/FiO₂ below 200, ARDS)
• Altered mental status (GCS below 13)
• AKI requiring RRT
• Multi-organ dysfunction
• Neurological melioidosis (always ICU for extended IV therapy)

Discharge Criteria

After Intensive Phase (Transition to Oral Eradication):

• Afebrile for ≥48 hours
• Clinically improved (resolving tachycardia, tachypnea, normalized BP without support)
• Tolerating oral intake
• Abscess drainage completed or not required
• CRP declining
• Arranged follow-up with ID clinic
• Patient/family education on eradication phase compliance

Contraindications to Discharge:

• Persistent fever
• Unable to tolerate oral TMP-SMX
• Uncontrolled diabetes (HbA1c greater than 9%, recurrent DKA)
• Undrained abscesses
• Concern for non-compliance (homelessness, addiction, cognitive impairment)

Follow-up

Eradication Phase Monitoring:

• Week 1-4: Weekly FBC (monitor for cytopenia), renal function, LFTs, clinical review
• Month 2-6: Monthly FBC, clinical review, CRP
• Imaging: Repeat CT at 3 months if abscesses present to confirm resolution

GP Letter Requirements:

• Diagnosis of melioidosis with date of onset
• Intensive phase antibiotic and duration
• Eradication phase: TMP-SMX 320/1600 mg BD + folinic acid 10 mg daily for 3-6 months (specify end date)
• Monitoring: Weekly FBC × 4 weeks, then monthly; cease if WCC below 2.0, neutrophils below 1.0, platelets below 100
• Red flags to return: Fever, new lumps, bone/joint pain, headache, neurological symptoms

Specialist Referral:

• Infectious Diseases: All cases - mandatory for duration and relapse surveillance
• Endocrinology: Uncontrolled diabetes (HbA1c greater than 9%)
• Renal: CKD Stage 4-5
• Addiction Medicine: Hazardous alcohol use

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Special Populations

Paediatric Considerations

• Less common than adults (10-15% of cases)
• Higher proportion of skin/soft tissue infection, parotid abscess
• Dosing: Weight-based (see Paediatric Dosing table)
• Eradication phase challenging due to palatability of TMP-SMX (liquid formulation available)

Pregnancy

• Rare but devastating - maternal mortality 40%, fetal mortality 50%
• Antibiotics:
  • Meropenem preferred over ceftazidime (better safety data)
  • TMP-SMX contraindicated in 1st trimester (neural tube defects) and 3rd trimester (kernicterus)
  • "Alternative eradication: Amoxicillin-clavulanate 875/125 mg TDS × 6 months (higher relapse risk - close monitoring)"
• Delivery: Consider early delivery if maternal deterioration despite antibiotics

Elderly

• Higher mortality (age greater than 60 years independent risk factor)
• Often multiple comorbidities (DM, CKD, COPD)
• Increased risk of AKI from ceftazidime/TMP-SMX - careful fluid balance and dose adjustment
• Cognitive impairment may reduce eradication phase compliance - arrange directly observed therapy (DOT) if needed

Indigenous Health

Important Note: Aboriginal, Torres Strait Islander, and Māori considerations:

Epidemiological Burden:

• Aboriginal and Torres Strait Islander peoples in northern Australia have 5-10× higher incidence (103-283 per 100,000/year vs 16.5 per 100,000 in non-Aboriginal)
• Represent 40-50% of all melioidosis cases in Top End NT
• Higher mortality due to delayed presentation, comorbidities, and social determinants of health

Risk Factor Clustering:

• Type 2 diabetes prevalence: 3-4× higher than non-Aboriginal Australians
• Chronic kidney disease: 4-5× higher, often reaching ESKD at younger age
• Hazardous alcohol use: More prevalent, associated with aspiration pneumonia
• Environmental exposure: Land management activities (burning, hunting), wet season work, overcrowded housing

Cultural Safety:

• Use Aboriginal and Torres Strait Islander Hospital Liaison Officers (AHLOs) for communication
• Family-centered care: Involve extended family in decision-making (with patient consent)
• Explain "long sickness" concept: Melioidosis can stay in body for years and come back
• Address health literacy: Use plain language, visual aids, interpreters if English not first language
• Respect cultural protocols: Same-gender care providers if requested, cultural smoking ceremonies
• Avoid assumptions about alcohol use (sensitive history-taking)

Practical Considerations:

• Eradication phase compliance: 6-month oral therapy challenging if living in remote community
  • Arrange pharmacy services in community (PBS Section 100 Remote Area Aboriginal Health Services)
  • Directly observed therapy (DOT) via local health clinic
  • Cultural education on importance of completing full course
• Follow-up: Telemedicine/RFDS clinic visits if unable to return to tertiary center
• Social determinants: Homelessness, food insecurity, transport - liaise with social work, Aboriginal health services

Māori Considerations (New Zealand - imported cases only):

• Melioidosis not endemic; cases from travel to Australia/SE Asia
• Cultural protocols: Karakia (prayer), whānau involvement, tikanga (customs)
• Health inequity: Māori have higher rates of diabetes, renal disease - same risk factors as Aboriginal Australians

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Pitfalls & Pearls

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Viva Practice

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OSCE Scenarios

Station 1: Acute Management of Melioidosis Septic Shock

Format: Resuscitation Station Time: 11 minutes Setting: ED Resuscitation Bay

Candidate Instructions:

You are the ED registrar in Darwin Hospital. You are asked to review a 55-year-old Aboriginal man who has just arrived by ambulance from a remote community 400 km away. He has been unwell for 3 days with fever, cough, and shortness of breath. The paramedics report: BP 75/40, HR 135, RR 35, SpO₂ 85% on room air, GCS 14 (E4 V4 M6), T 39.9°C. He has type 2 diabetes. It is January (wet season).

Your task: Lead the initial resuscitation of this patient. A nurse is available to assist. You have 8 minutes.

Examiner Instructions:

The candidate should demonstrate a systematic ABCDE approach to managing septic shock in a patient with likely melioidosis. Key actions include:

1. Airway: Assessment, consider intubation given GCS 14 and severe hypoxemia
2. Breathing: High-flow oxygen, prepare for mechanical ventilation
3. Circulation: IV access, bloods including cultures, aggressive fluid resuscitation, early vasopressors
4. Antibiotics: Melioidosis-appropriate empiric therapy (ceftazidime or meropenem) within 60 minutes
5. Senior support: ICU, ID consult
6. Investigations: CXR, CT, blood cultures

The nurse will respond to requests and provide updates. Monitor for closed-loop communication, prioritization, and leadership.

Simulated Patient/Nurse Brief:

You are a nurse assisting in the resus bay. The patient is on the trolley, appearing toxic and dyspneic.

• If candidate requests oxygen: "I've applied 15L via non-rebreather, SpO₂ now 90%"
• If candidate requests IV access: "I've inserted two 16G cannulae in the ACF bilaterally"
• If candidate requests bloods: "What bloods would you like?" (expect: blood cultures, VBG, FBC, UEC, CRP, glucose)
• If candidate orders fluids: "500 mL Hartmann's running wide open. BP now 85/50"
• If candidate orders antibiotics: "Which antibiotics?"
  • If ceftazidime/meropenem: "Yes, I'll get that now"
  • If piperacillin-tazobactam/ceftriaxone: "Are you sure? We're in Darwin during wet season, and he's a diabetic Aboriginal man" (prompt candidate to reconsider melioidosis)
• If candidate requests CXR: "Portable CXR shows right upper lobe consolidation with early cavitation"
• If candidate requests ICU: "ICU reg is on their way"

Marking Criteria:

Expected Standard:

• Pass: ≥6/11
• Key discriminators:
  • Recognition of melioidosis as primary differential given epidemiological context
  • Appropriate antibiotic choice (ceftazidime or meropenem) - failure to choose correct antibiotic is a critical fail
  • Early ICU referral given septic shock

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Station 2: Communication - Explaining Melioidosis Diagnosis and Long-Term Treatment

Format: Communication Station Time: 11 minutes Setting: ED Consultation Room

Candidate Instructions:

You are the ED registrar. You have just admitted a 42-year-old Aboriginal woman from Katherine with melioidosis (bacteremic pneumonia). She has completed 14 days of IV ceftazidime and is now ready for discharge on oral eradication therapy. She has type 2 diabetes and lives in a remote community 300 km from Darwin. She has limited English proficiency (Kriol is her first language).

Your task: Explain the diagnosis, the need for 3 months of oral antibiotics, and arrange follow-up. An Aboriginal Health Liaison Officer is present to assist with interpretation.

Simulated Patient Brief:

You are a 42-year-old Aboriginal woman from Katherine region. You have been in hospital for 2 weeks with pneumonia and received IV antibiotics. You are feeling much better now and want to go home to your community to be with your family. You are worried about taking tablets for 3 months - that seems like a very long time. You have had bad experiences with hospitals in the past (felt rushed, not listened to) and are a bit mistrustful of doctors. You have limited English proficiency and prefer to speak Kriol.

Questions/Concerns to Raise:

• "Why do I need tablets for 3 months? I'm feeling better now."
• "What happens if I stop early?"
• "Can I get the tablets in my community?"
• "Will I have to come back to Darwin for check-ups?"
• (Through AHLO): "My Aunty says melioidosis is a 'land sickness' and I should see traditional healer"

Aboriginal Health Liaison Officer Brief:

You are present to assist with interpretation and cultural safety. You know this patient and her family. You can clarify medical terms in Kriol and advocate for culturally appropriate care. Prompt the candidate if they use jargon or speak too quickly.

Marking Criteria:

Expected Standard:

• Pass: ≥6/11
• Key discriminators:
  • Uses plain language, not medical jargon
  • Demonstrates cultural safety (respects traditional healing, involves AHLO)
  • Addresses practical barriers to compliance (community access to medications)

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Station 3: History - Febrile Returned Traveler with Possible Melioidosis

Format: History Taking Time: 11 minutes Setting: ED Cubicle

Candidate Instructions:

You are the ED registrar in a Melbourne hospital. A 32-year-old man presents with 5 days of fever, headache, and myalgia. He returned from a 3-week holiday to Thailand 10 days ago. Triage notes: T 38.9°C, BP 125/75, HR 105, RR 18, SpO₂ 97% RA.

Your task: Take a focused history to determine the cause of fever in this returned traveler. You have 8 minutes.

Simulated Patient Brief:

You are a 32-year-old IT worker who just returned from a 3-week holiday to Thailand (Bangkok, Chiang Mai, Phuket). You have had fever (feeling very hot, sweats at night) for 5 days, along with headache, muscle aches, and general fatigue. You feel quite unwell. You have no past medical history and take no medications. You have not had any vaccines before travel (you didn't think you needed them).

Travel Details (volunteer if asked):

• Stayed in budget hotels and guesthouses
• Ate street food frequently (pad thai, mango sticky rice)
• Swam in rivers and waterfalls in Chiang Mai
• Rode a motorbike and had a small fall, scraping your left shin (didn't seek medical attention, cleaned it with water)
• Did not use mosquito repellent consistently
• No sexual contacts during travel
• Returned to Australia 10 days ago

Symptoms (if asked directly):

• Fever: Yes, high fevers every evening, sweating at night
• Cough: Mild dry cough started yesterday
• Headache: Yes, frontal headache, continuous
• Rash: No
• Diarrhea: One episode of loose stools 2 weeks ago (in Phuket), resolved
• Abdominal pain: No
• Joint pain: Generalized myalgia, no specific joint swelling

Marking Criteria:

Expected Standard:

• Pass: ≥6/11
• Key discriminators:
  • Identifies wound exposure + freshwater exposure in Thailand as risk for melioidosis
  • Constructs broad differential (dengue, typhoid, leptospirosis, melioidosis, malaria - though Thailand travel areas often low malaria risk)
  • Asks about time since return (10 days - within incubation period for melioidosis which is typically 1-21 days)

Examiner Notes:

The key history features pointing to melioidosis are:

• Travel to endemic area (Thailand)
• Freshwater exposure (swimming in rivers/waterfalls)
• Wound contamination (motorbike fall, shin scrape, cleaned with water - likely contaminated)
• Incubation period 10 days since return (melioidosis incubation 1-21 days, average 9 days)
• Fever + mild respiratory symptoms (early pneumonic melioidosis)

Differential diagnoses should include:

• Melioidosis (wound + water exposure)
• Dengue fever (mosquito-borne, common in Thailand)
• Typhoid fever (food/water-borne)
• Leptospirosis (freshwater exposure)
• Malaria (if traveled to border regions, but low risk in Bangkok/Chiang Mai/Phuket)
• Chikungunya (mosquito-borne, less common than dengue)

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SAQ Practice

Question 1: Antibiotic Selection (6 marks)

Stem: A 50-year-old man with type 2 diabetes presents to Darwin ED with 2 days of fever and cough. CXR shows right lower lobe consolidation. You suspect melioidosis.

Question: List SIX classes of antibiotics to which Burkholderia pseudomallei is intrinsically resistant, and state the TWO antibiotic classes that ARE effective for treating melioidosis.

Time: 3 minutes

Model Answer:

Intrinsically resistant (6 marks - 1 mark each):

1. Penicillins (including anti-pseudomonal penicillins like piperacillin)
2. First-generation cephalosporins (e.g., cephazolin)
3. Second-generation cephalosporins (e.g., cefuroxime, cefoxitin)
4. Aminoglycosides (e.g., gentamicin, tobramycin)
5. Macrolides (e.g., azithromycin, clarithromycin)
6. Polymyxins (e.g., colistin) - accept fluoroquinolones as alternative

Effective antibiotic classes (2 bonus marks if both correct):

1. Third-generation anti-pseudomonal cephalosporins (ceftazidime)
2. Carbapenems (meropenem, imipenem)

Examiner Notes:

• Accept: "Beta-lactams" for #1 if candidate qualifies that NOT all beta-lactams are ineffective (ceftazidime/carbapenems work)
• Accept: "Cephalosporins" if candidate specifies 1st/2nd generation
• Accept: Fluoroquinolones as 6th resistant class (variable susceptibility, not recommended for monotherapy)
• Do NOT accept: "Broad-spectrum antibiotics" (too vague)
• Must specify ceftazidime OR carbapenems as effective classes

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Question 2: Two-Phase Treatment (8 marks)

Stem: A 45-year-old Aboriginal woman from Katherine is diagnosed with bacteremic melioidosis causing pneumonia. She has no abscesses on CT imaging.

Question: Outline the two-phase treatment regimen for uncomplicated melioidosis, including drug names, doses, routes, and durations.

Time: 4 minutes

Model Answer:

Intensive Phase (4 marks):

• Drug: Ceftazidime (1 mark)
• Dose: 2g (or 50 mg/kg) (0.5 mark)
• Route: Intravenous (0.5 mark)
• Frequency: Every 6-8 hours (0.5 mark)
• Duration: Minimum 10-14 days (0.5 mark)
• Alternative: Meropenem 1g IV Q8h (1 mark for mentioning alternative)

Eradication Phase (4 marks):

• Drug: Trimethoprim-sulfamethoxazole (TMP-SMX / co-trimoxazole) (1 mark)
• Dose: 320/1600 mg (two double-strength tablets) (0.5 mark)
• Route: Oral (0.5 mark)
• Frequency: Twice daily (0.5 mark)
• Duration: 3 months for uncomplicated disease (1 mark)
• Adjunct: Folinic acid 10 mg daily (0.5 mark)
• Note: 6 months if bone/joint/CNS involvement (0.5 mark bonus)

Examiner Notes:

• Accept: Co-trimoxazole, Bactrim, Septrin as TMP-SMX
• Accept: "Leucovorin" instead of folinic acid
• Must specify duration for both phases to get full marks
• Must state "minimum" 10-14 days for intensive phase (can be extended to 4-8 weeks)
• Deduct marks if candidate does not mention need for 3 months oral therapy (common error)

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Question 3: Indigenous Health Disparities (8 marks)

Stem: Aboriginal and Torres Strait Islander peoples in northern Australia have a disproportionately high burden of melioidosis.

Question: List FOUR reasons why the incidence of melioidosis is higher in Aboriginal and Torres Strait Islander populations, and describe TWO strategies to improve adherence to the 3-6 month eradication phase in remote communities.

Time: 4 minutes

Model Answer:

Four reasons for higher incidence (4 marks - 1 mark each):

1. Higher prevalence of type 2 diabetes (3-4× higher than non-Aboriginal Australians)
2. Higher prevalence of chronic kidney disease (4-5× higher, often reaching ESKD at younger age)
3. Greater environmental exposure to B. pseudomallei (land management activities, wet season work, living in endemic areas)
4. Hazardous alcohol use (more prevalent, associated with aspiration pneumonia)

Accept also:

• Socioeconomic factors (overcrowded housing, poverty, limited healthcare access)
• Delayed presentation to healthcare due to remoteness, transport barriers
• Occupational exposure (farming, construction, outdoor work)

Two strategies to improve eradication phase adherence (4 marks - 2 marks each):

1. Directly Observed Therapy (DOT): Arrange for patient to take daily TMP-SMX at local community health clinic or via Aboriginal Health Worker under supervision to ensure compliance
2. Cultural safety and health literacy: Use Aboriginal and Torres Strait Islander Health Liaison Officers, plain language education, involve family/whānau, use visual aids/medication calendars, provide culturally appropriate counseling on importance of completing full course

Accept also:

• Remove cost barriers (PBS Section 100 - medications free for Aboriginal and Torres Strait Islander peoples)
• Telemedicine follow-up with ID clinic to reduce need for long-distance travel
• Address side effects proactively (folinic acid, antiemetics)
• Phone/SMS medication reminders
• Community-based case management with Aboriginal Health Workers

Examiner Notes:

• Must identify diabetes/CKD as risk factors to get marks (these are most important)
• Must give specific, actionable strategies for adherence (not just "educate patient")
• Award 2 marks per strategy if candidate explains HOW it works (not just lists it)
• Do NOT accept vague answers like "improve access to healthcare" without specifics

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Question 4: Neurological Melioidosis (8 marks)

Stem: A 52-year-old man with confirmed melioidosis develops severe headache, diplopia, and ataxia on day 5 of IV ceftazidime therapy. MRI brain shows a 3 cm ring-enhancing lesion in the pons.

Question: Describe FOUR key differences in the management of neurological melioidosis compared to non-CNS melioidosis.

Time: 4 minutes

Model Answer:

Four key differences (8 marks - 2 marks each):

1. Antibiotic choice: Meropenem 1g IV Q8h preferred over ceftazidime due to better CNS penetration (20-30% vs 10-20%) (2 marks)

2. Duration of intensive phase: 6-12 months of IV antibiotics (not 10-14 days) due to difficulty eradicating intracellular bacteria from CNS tissue and high relapse risk if treated with standard duration (2 marks)

3. Total treatment duration: 12-18 months total therapy (6-12 months IV + 6 months oral TMP-SMX eradication) compared to 3-6 months total for non-CNS disease (2 marks)

4. Monitoring and imaging: Serial MRI brain every 4-6 weeks to assess abscess response; consider neurosurgical drainage if abscess enlarging despite appropriate antibiotics (though brainstem location makes surgery high-risk) (2 marks)

Accept also (2 marks each):

• Adjunctive corticosteroids: Consider dexamethasone 4-8 mg IV Q6h to reduce cerebral edema and mass effect (controversial - may impair immune response)
• ICU admission: Neurological melioidosis requires ICU-level monitoring due to risk of brainstem herniation, respiratory depression, raised ICP
• Prognosis: 15% mortality even with appropriate treatment; higher relapse risk; neurological sequelae (cranial nerve palsies, cognitive impairment) common

Examiner Notes:

• Must specify DURATION changes (6-12 months IV) to get full marks - this is the most important difference
• Must mention meropenem preference for CNS penetration
• Award marks for any 4 correct differences (candidate can choose which 4)
• Do NOT award marks for generic answers like "more aggressive treatment" without specifics

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Australian Guidelines

Therapeutic Guidelines Australia

Antibiotic (eTG complete):

• Melioidosis - Intensive phase: Ceftazidime 50 mg/kg up to 2g IV Q6-8h OR meropenem 25 mg/kg up to 1g IV Q8h for 10-14 days (extend to 4-8 weeks for severe disease, CNS, bone/joint, extensive abscesses)
• Melioidosis - Eradication phase: Trimethoprim + sulfamethoxazole 160/800 mg (1 double-strength tablet) to 320/1600 mg (2 double-strength tablets) PO BD for 3 months (uncomplicated) or 6 months (bone/joint/CNS)
• Adjunct: Folinic acid (leucovorin) 5-10 mg PO daily during eradication phase to reduce bone marrow toxicity

Northern Territory Guidelines

NT Centre for Disease Control (CDC) - Melioidosis Management:

• All suspected melioidosis in Top End should have blood cultures, sputum culture, urine culture, wound swabs
• Empiric therapy for septic patient with risk factors: Ceftazidime 2g IV Q6-8h (do not wait for cultures)
• Notify NT CDC within 5 business days (notifiable disease)
• Darwin "Bundle of Care" (responsible for mortality reduction from 30% to 8%):
  1. Early recognition and appropriate antibiotics
  2. Aggressive resuscitation (30 mL/kg fluids, vasopressors)
  3. Source control (drain abscesses greater than 5 cm)
  4. Prolonged IV therapy (minimum 10-14 days, extend as needed)
  5. Supervised eradication phase (monthly FBC, ID clinic)
  6. Long-term surveillance for relapse

Queensland Health Guidelines

Queensland Melioidosis Management Protocol:

• Melioidosis is endemic in Far North Queensland (Cairns, Torres Strait)
• All febrile patients during wet season (November-April) with diabetes or risk factors should have melioidosis considered
• Empiric antibiotics in septic patient: Ceftazidime or meropenem
• Notifiable disease - notify local Public Health Unit

Western Australia Guidelines

WA Health - Melioidosis in Kimberley Region:

• Endemic in Kimberley; incidence 20-30 per 100,000 in Broome area
• High index of suspicion in Aboriginal patients with diabetes + wet season exposure
• Retrieval protocols for remote patients to Broome or Perth for ICU care

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Remote/Rural Considerations

Pre-Hospital

Ambulance/Retrieval:

• Paramedics in endemic areas (Top End, FNQ, Kimberley) should consider melioidosis in septic patients with diabetes during wet season
• Pre-hospital management: Oxygen, IV access, fluid resuscitation
• Early notification to receiving hospital: "Diabetic patient from [remote community], septic shock, wet season - suspect melioidosis" triggers ED to prepare ceftazidime/meropenem
• Intubation pre-hospital if GCS ≤8 or severe respiratory distress

Royal Flying Doctor Service (RFDS):

• RFDS is primary retrieval service for remote/rural northern Australia
• Melioidosis is a common reason for RFDS retrieval from remote communities during wet season
• RFDS aircraft carry ceftazidime and meropenem for in-flight administration
• Retrieval priorities: Stabilize (ABCs), IV antibiotics, transfer to tertiary center (Darwin, Cairns, Broome)

Resource-Limited Setting

Remote Health Clinics:

• Limited diagnostic capacity: No blood cultures, no CT scanning
• Clinical diagnosis based on: Fever + diabetes + wet season + endemic area = treat as melioidosis
• Antibiotic availability: Ceftazidime and meropenem may not be stocked - call RFDS for retrieval
• If antibiotics available: Start ceftazidime 2g IV Q8h, arrange urgent retrieval
• Telemedicine: Use telehealth to consult with ID physician in Darwin/Cairns for advice

Modified Approach:

• Cannot confirm diagnosis (no cultures) - must treat empirically
• Cannot monitor response (no CRP, imaging) - clinical assessment only
• Cannot manage complications (no ICU) - early retrieval essential

Retrieval

Criteria for Retrieval to Tertiary Center:

• All suspected melioidosis cases from remote areas should be retrieved for:
  • Diagnostic confirmation (blood cultures)
  • IV antibiotics (ceftazidime/meropenem)
  • Imaging (CXR, CT to screen for abscesses)
  • ICU-level care if needed
  • Infectious Diseases specialist input

RFDS Coordination:

• RFDS Central Operations: 1800 625 800 (NT/SA/QLD)
• RFDS Western Operations: 1300 367 707 (WA/VIC/TAS)
• Retrieval flight time: Remote community to Darwin typically 1-3 hours
• In-flight care: Ventilation, vasopressors, IV antibiotics

Pre-Retrieval Stabilization:

1. Airway: Intubate if GCS ≤8, SpO₂ below 90% despite high-flow O₂
2. Breathing: Mechanical ventilation, target SpO₂ 92-96%
3. Circulation: IV access, fluid resuscitation (30 mL/kg), vasopressors (noradrenaline) if MAP below 65 despite fluids
4. Antibiotics: Ceftazidime 2g IV or meropenem 1g IV if available
5. Glucose: Check BSL, manage DKA if present (common comorbidity)
6. Monitoring: Continuous vital signs, urine output (IDC)

Telemedicine

Remote Consultation:

• NT Telehealth: Remote health clinics can consult with Darwin ID physicians via video link
• Advice on: Antibiotic choice, duration, need for retrieval, follow-up planning
• Monthly eradication phase monitoring can be done via telemedicine (clinical review + local FBC)

Applications:

• Initial management advice for remote clinic staff
• Follow-up during eradication phase (monthly ID clinic via video)
• Education for Aboriginal Health Workers on melioidosis recognition

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References

Guidelines

1. Australian Government Department of Health and Aged Care. National Notifiable Diseases Surveillance System (NNDSS) - Melioidosis case definition. 2023. Available from: https://www.health.gov.au/diseases/melioidosis
2. Therapeutic Guidelines. eTG complete: Antibiotic - Melioidosis. Therapeutic Guidelines Ltd; 2024.
3. Northern Territory Centre for Disease Control. Melioidosis Fact Sheet and Management Guidelines. NT Health; 2022.
4. Queensland Health. Melioidosis Management Protocol. QLD Health; 2021.

Key Evidence - Epidemiology

5. Birnie E, Virk HS, Savelkoel J, Spijker R, Bertherat E, Dance DAB, Limmathurotsakul D, Wiersinga WJ, Devleesschauwer B, Haagsma JA. Global burden of melioidosis in 2015: a systematic review and data synthesis. Lancet Infect Dis. 2019;19(8):892-902. PMID: 31227327

6. Currie BJ, Ward L, Cheng AC. The epidemiology and clinical spectrum of melioidosis: 540 cases from the 20 year Darwin prospective study. PLoS Negl Trop Dis. 2010;4(11):e900. PMID: 21152057

7. Currie BJ, Mayo M, Anstey NM, Donohoe P, Haase A, Kemp DJ. A cluster of melioidosis cases from an endemic region is clonal and is linked to the water supply using molecular typing of Burkholderia pseudomallei isolates. Am J Trop Med Hyg. 2001;65(3):177-179. PMID: 11561701

8. Limmathurotsakul D, Golding N, Dance DA, Messina JP, Pigott DM, Moyes CL, Rolim DB, Bertherat E, Day NP, Peacock SJ, Hay SI. Predicted global distribution of Burkholderia pseudomallei and burden of melioidosis. Nat Microbiol. 2016;1(1):15008. PMID: 26877885 [Correction: PMID: 26916619]

9. Parameswaran U, Baird RW, Ward LM, Currie BJ. Melioidosis at Royal Darwin Hospital in the big 2009-2010 wet season: comparison with the preceding 20 years. Med J Aust. 2012;196(5):345-348. PMID: 22432675

10. Stewart JD, Smith S, Binotto E, McBride WJ, Currie BJ, Hanson J. The epidemiology and clinical features of melioidosis in Far North Queensland: implications for patient management. PLoS Negl Trop Dis. 2017;11(3):e0005411. PMID: 28288649

Key Evidence - Indigenous Health

11. Currie BJ, Fisher DA, Howard DM, Burrow JN, Selvanayagam S, Snelling PL, Anstey NM, Mayo MJ. The epidemiology of melioidosis in Australia and Papua New Guinea. Acta Trop. 2000;74(2-3):121-127. PMID: 10674638

12. Stephens DP, Thomas JH, Ward LM, Currie BJ. Melioidosis causing critical illness: a review of 24 years of experience from the Royal Darwin Hospital ICU. Crit Care Resusc. 2016;18(4):243-247. PMID: 27903207

13. Ralph A, McBride J, Currie BJ. Transmission of Burkholderia pseudomallei via breast milk in northern Australia. Pediatr Infect Dis J. 2004;23(12):1169-1171. PMID: 15626959

14. Gibney KB, Cheng AC, Currie BJ. Cutaneous melioidosis in the tropical top end of Australia: a prospective study and review of the literature. Clin Infect Dis. 2008;47(5):603-609. PMID: 18652553

Key Evidence - Clinical Presentation

15. Currie BJ, Fisher DA, Howard DM, Burrow JN, Lo D, Selva-Nayagam S, Anstey NM, Huffam SE, Snelling PL, Marks PJ, Stephens DP, Lum GD, Jacups SP, Krause VL. Endemic melioidosis in tropical northern Australia: a 10-year prospective study and review of the literature. Clin Infect Dis. 2000;31(4):981-986. PMID: 11049780

16. Chaowagul W, White NJ, Dance DA, Wattanagoon Y, Naigowit P, Davis TM, Looareesuwan S, Pitakwatchara N. Melioidosis: a major cause of community-acquired septicemia in northeastern Thailand. J Infect Dis. 1989;159(5):890-899. PMID: 2708842

17. Currie BJ, Fisher DA, Anstey NM, Jacups SP. Melioidosis: acute and chronic disease, relapse and re-activation. Trans R Soc Trop Med Hyg. 2000;94(3):301-304. PMID: 10974013

18. Cheng AC, Currie BJ, Dance DAB, Funnell SGP, Limmathurotsakul D, Simpson AJH, Peacock SJ. Clinical definitions of melioidosis. Am J Trop Med Hyg. 2013;88(3):411-413. PMID: 23382159

Key Evidence - Neurological Melioidosis

19. Currie BJ, Jacups SP, Cheng AC, Fisher DA, Anstey NM, Huffam SE, Krause VL. Melioidosis epidemiology and risk factors from a prospective whole-population study in northern Australia. Trop Med Int Health. 2004;9(11):1167-1174. PMID: 15548312

20. Suntornsut P, Kasemsup N, Silairatana S, Wongsuvan G, Chaowagul W, Limmathurotsakul D, Chierakul W, Peacock SJ, Day NPJ, Chetchotisakd P. Improvement of survival in patients with melioidosis in northeast Thailand. Am J Trop Med Hyg. 2013;89(3):568-570. PMID: 23836571

21. Wasana P, Somsri M, Krairojananan P, Dejsirilert S, Migler R, Thavirot P, Chetchotisakd P. Neurological melioidosis in northeastern Thailand. Trans R Soc Trop Med Hyg. 2004;98(5):283-286. PMID: 15044798

Key Evidence - Diagnostics

22. Limmathurotsakul D, Jamsen K, Arayawichanont A, Simpson JA, White LJ, Lee SJ, Peacock SJ, Titball RW, Bancroft GJ, Vanaporn M, Wuthiekanun V, Day NP, Chantratita N. Defining the true sensitivity of culture for the diagnosis of melioidosis using Bayesian latent class models. PLoS One. 2010;5(8):e12485. PMID: 20830192

23. Cheng AC, Ward L, Godoy D, Norton R, Mayo M, Gal D, Spratt BG, Currie BJ. Genetic diversity of Burkholderia pseudomallei isolates in Australia. J Clin Microbiol. 2008;46(1):249-254. PMID: 17989198

24. Peacock SJ, Schweizer HP, Dance DA, Smith TL, Gee JE, Wuthiekanun V, DeShazer D, Steinmetz I, Tan P, Currie BJ. Management of accidental laboratory exposure to Burkholderia pseudomallei and B. mallei. Emerg Infect Dis. 2008;14(7):e2. PMID: 18598616

Key Evidence - Treatment

25. Cheng AC, Stephens DP, Anstey NM, Currie BJ. Adjunctive granulocyte colony-stimulating factor for treatment of septic shock due to melioidosis. Clin Infect Dis. 2004;38(1):32-37. PMID: 14679445

26. Cheng AC, McBryde ES, Wuthiekanun V, Chierakul W, Amornchai P, Day NP, White NJ, Peacock SJ. Dosing regimens of cotrimoxazole (trimethoprim-sulfamethoxazole) for melioidosis. Antimicrob Agents Chemother. 2009;53(10):4193-4199. PMID: 19596869

27. Chetchotisakd P, Porramatikul S, Mootsikapun P, Anunnatsiri S, Thinkhamrop B. Randomized, double-blind, controlled study of ceftazidime or ceftazidime plus trimethoprim-sulfamethoxazole for the treatment of severe melioidosis. Clin Infect Dis. 2001;33(1):29-34. PMID: 11389491

28. Chierakul W, Winothai W, Wattanawaitunechai C, Wuthiekanun V, Rugtaengan T, Rattanalertnavee J, Jitpratoom P, Chaowagul W, Singhasivanon P, White NJ, Day NP, Peacock SJ. Melioidosis in 6 tsunami survivors in southern Thailand. Clin Infect Dis. 2005;41(7):982-990. PMID: 16142663

29. Chaowagul W, Suputtamongkol Y, Dance DA, Rajchanuvong A, Pattara-arechachai J, White NJ. Relapse in melioidosis: incidence and risk factors. J Infect Dis. 1993;168(5):1181-1185. PMID: 8228352

30. Dance DAB, Limmathurotsakul D, Currie BJ, Peacock SJ. Burkholderia pseudomallei: challenges for the clinical microbiology laboratory. J Clin Microbiol. 2023;61(5):e0018322. PMID: 36656031

31. Inglis TJJ, Rolim DB, Rodriguez JLN. Clinical guideline for diagnosis and management of melioidosis. Rev Inst Med Trop Sao Paulo. 2006;48(1):1-4. PMID: 16547570

32. Suputtamongkol Y, Chaowagul W, Chetchotisakd P, Lertpatanasuwun N, Intaranongpai S, Ruchutrakool T, Budhsarawong D, Mootsikapun P, Wuthiekanun V, Teerawatasook N, Lulitanond A. Risk factors for melioidosis and bacteremic melioidosis. Clin Infect Dis. 1999;29(2):408-413. PMID: 10476750

33. Suputtamongkol Y, Hall AJ, Dance DA, Chaowagul W, Rajchanuvong A, Smith MD, White NJ. The epidemiology of melioidosis in Ubon Ratchatani, northeast Thailand. Int J Epidemiol. 1994;23(5):1082-1090. PMID: 7860160

34. White NJ, Dance DA, Chaowagul W, Wattanagoon Y, Wuthiekanun V, Pitakwatchara N. Halving of mortality of severe melioidosis by ceftazidime. Lancet. 1989;2(8665):697-701. PMID: 2570956

Key Evidence - G-CSF Adjunct

35. Cheng AC, Limmathurotsakul D, Chierakul W, Getchalarat N, Wuthiekanun V, Stephens DP, Day NP, White NJ, Chaowagul W, Currie BJ, Peacock SJ. A randomized controlled trial of granulocyte colony-stimulating factor for the treatment of severe sepsis due to melioidosis in Thailand. Clin Infect Dis. 2007;45(3):308-314. PMID: 17599307

36. Cheng AC, Stephens DP, Anstey NM, Currie BJ. Adjunctive granulocyte colony-stimulating factor for treatment of septic shock due to melioidosis. Clin Infect Dis. 2004;38(1):32-37. PMID: 14679445

Key Evidence - Meropenem vs Ceftazidime

37. Chetchotisakd P, Chierakul W, Chaowagul W, Anunnatsiri S, Phimda K, Mootsikapun P, Wuthiekanun V, Peacock SJ, Limmathurotsakul D, Day NP, White NJ. Trimethoprim-sulfamethoxazole versus trimethoprim-sulfamethoxazole plus doxycycline as oral eradicative treatment for melioidosis (MERTH): a multicentre, double-blind, non-inferiority, randomised controlled trial. Lancet. 2014;383(9919):807-814. PMID: 24284287

38. Cheng AC, Fisher DA, Anstey NM, Stephens DP, Jacups SP, Currie BJ. Outcomes of patients with melioidosis treated with meropenem. Antimicrob Agents Chemother. 2004;48(5):1763-1765. PMID: 15105135

39. Pitman MC, Luck T, Marshall CS, Anstey NM, Ward L, Currie BJ. Intravenous therapy duration and outcomes in melioidosis: a new treatment paradigm. PLoS Negl Trop Dis. 2015;9(3):e0003586. PMID: 25803844

Key Evidence - Relapse and Long-Term Outcomes

40. Limmathurotsakul D, Peacock SJ. Melioidosis: a clinical overview. Br Med Bull. 2011;99:125-139. PMID: 21558159

41. Wiersinga WJ, Virk HS, Torres AG, Currie BJ, Peacock SJ, Dance DAB, Limmathurotsakul D. Melioidosis. Nat Rev Dis Primers. 2018;4:17107. PMID: 29388572

42. Currie BJ. Melioidosis: evolving concepts in epidemiology, pathogenesis, and treatment. Semin Respir Crit Care Med. 2015;36(1):111-125. PMID: 25643275

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This topic was generated using the ACEM Emergency Medicine skill with evidence-based content from PubMed and Australian clinical guidelines. Last updated: 2026-01-24.