Clinical Presentations of Melioidosis
Melioidosis presents most commonly as severe community-acquired pneumonia with septicemia, but can manifest across a spectrum from asymptomatic infection to fulminant septic shock with disseminated abscesses in multiple organs. 1, 2
Primary Clinical Manifestations
Pulmonary Disease
- Pneumonia is the most common clinical presentation, ranging from progressive pneumonia to necrotizing pneumonia with respiratory distress 1, 3
- Patients may present with severe community-acquired pneumonia that fails to respond to standard empiric therapy 2
Disseminated Disease with Abscesses
- Deep-seated collections or organ abscesses occur frequently, particularly in the liver and spleen 4, 5
- Multiple hepatic and splenic abscesses are characteristic presentations, especially in diabetic and alcoholic patients 5
- Soft tissue infections and localized tissue abscesses can occur 3
Severe Systemic Disease
- Fulminant septicemia with septic shock represents the most severe presentation 1, 3
- Dissemination to multiple organs with characteristic abscess formation 1
Specific Organ Involvement
- Central nervous system infection (neurologic melioidosis) requires extended treatment duration 2, 4
- Osteomyelitis and septic arthritis are recognized complications requiring prolonged therapy 4, 3
- Joint involvement can occur either as a primary source or later in disease course 3
Chronic Presentations
- Chronic localized infection mimicking tuberculosis or other chronic illnesses 1
- Pyrexia of unknown origin in endemic areas should prompt consideration of melioidosis 1
Key Risk Factors to Identify
- Diabetes mellitus is the predominant risk factor, particularly for fatal forms of disease 3
- Alcoholism significantly increases risk, especially when combined with diabetes 5
- Immunocompromised states predispose to more severe manifestations 3
Diagnostic Pitfalls to Avoid
- Physicians frequently misdiagnose melioidosis as tuberculosis, pneumonia, or other pyogenic infections due to protean manifestations 1
- There is no pathognomonic feature specific to melioidosis 1
- B. pseudomallei can be confused with closely related bacteria and dismissed as culture contaminants 2
- The disease may occur beyond traditional endemic boundaries 1
Treatment Algorithm
Intensive Phase (Minimum 14 Days IV)
- For severe melioidosis, meropenem or imipenem are preferred first-line agents with superior clinical outcomes compared to ceftazidime 6, 4
- Ceftazidime (100 mg/kg/day) remains an acceptable alternative if carbapenems are unavailable 6, 7
- Extend intensive phase to 4-8 weeks or longer for:
- Consider adding G-CSF 300 mg IV for 10 days in melioidosis-induced septic shock 6, 7
Eradication Phase (3-6 Months)
- TMP-SMX is the drug of choice for eradication phase to prevent the 13% relapse rate seen over 10 years 4, 6
- Weight-based dosing:
- Add folic acid 0.1 mg/kg up to 5 mg daily to prevent antifolate effects 6
- For CNS involvement: Use higher TMP-SMX dosing at 8/40 mg/kg IV/PO every 12 hours (up to 320/1600 mg) and extend duration to 4-8 weeks or longer 6
Alternative Regimens
- Amoxicillin-clavulanate (20/5 mg/kg every 8 hours, maximum 1500/375 mg every 8 hours) for pregnant women, children, or TMP-SMX intolerance, though significantly less effective 4, 6, 7
- Doxycycline can be used as alternative if TMP-SMX contraindicated 4, 7
Critical Antibiotic Resistance Patterns
- B. pseudomallei is inherently resistant to: penicillin, ampicillin, first- and second-generation cephalosporins, gentamicin, streptomycin, polymyxin, ertapenem, azithromycin, and moxifloxacin 4, 6, 7
- Avoid ceftriaxone and cefotaxime as these are associated with higher mortality rates 6