Burkholderia pseudomallei: Difference between revisions
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Burkholderia pseudomallei
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===Microbiology=== |
===Microbiology=== |
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*Oxidase [[Oxidase::positive]], indole [[Indole::negative]] [[Stain::Gram-negative]] [[ |
*Oxidase [[Oxidase::positive]], indole [[Indole::negative]] [[Stain::Gram-negative]] [[Shape::bacillus]] with "'''safety pin'''" appearance (i.e. bipolar staining) |
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*[[Hemolysis::Non-hemolytic]] |
*[[Hemolysis::Non-hemolytic]] |
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*Colonies start small, smooth, cream-coloured with a metallic sheen, but become dry and wrinkly after 1 to 2 days of incubation |
*Colonies start small, smooth, cream-coloured with a metallic sheen, but become dry and wrinkly after 1 to 2 days of incubation |
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*Incubation period [[Usual incubation period::9 days]] (range [[Incubation period range::1 to 21 days]]) |
*Incubation period [[Usual incubation period::9 days]] (range [[Incubation period range::1 to 21 days]]) |
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*Presentations can vary from asymptomatic, skin ulcers, abscesses, latent infection, chronic pneumonia (similar to TB), or fulminant shock[[CiteRef::diemert2010th]] |
*Presentations can vary from asymptomatic, skin ulcers, abscesses, latent infection, chronic pneumonia (similar to TB), or fulminant shock[[CiteRef::diemert2010th]][[CiteRef::meumann2011cl]] |
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**[[Pneumonia]] (50%) |
**[[Pneumonia]] (50%) |
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**Genitourinary infection (15%) |
**Genitourinary infection (15%) |
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Latest revision as of 13:36, 25 May 2021
Background
- Also called melioidosis or Whitmore's disease
Microbiology
- Oxidase positive, indole negative Gram-negative bacillus with "safety pin" appearance (i.e. bipolar staining)
- Non-hemolytic
- Colonies start small, smooth, cream-coloured with a metallic sheen, but become dry and wrinkly after 1 to 2 days of incubation
- Inherently resistant to polymixins
Epidemiology
- Humans and animals
- Important cause of death in south-east Asia and northern Australia
- Up to 80% seroprevalence in Thailand, mostly asymptomatic
- More cases during the rainy season
- Sporadic cases elsewhere, including the Middle East, Africa, and the Americas
- May have latent disease with reactivation much later
- Acquired by percutaneous inoculation, inhalation (esp. lab workers), and ingestion
- Risk factors for clinical disease
- Diabetes
- Heavy alcohol use
- Chronic lung disease
- Chronic kidney disease
- Treatment with glucocorticoids
- Cancer
- Thalassemia
Clinical Manifestations
- Incubation period 9 days (range 1 to 21 days)
- Presentations can vary from asymptomatic, skin ulcers, abscesses, latent infection, chronic pneumonia (similar to TB), or fulminant shock12
- Pneumonia (50%)
- Genitourinary infection (15%)
- Skin infection (15%), with ulcers, nodules, or abscesses
- Primary bacteremia (10%)
- Septic arthritis/OM (3-5%)
- Neuro (3-5%)
- Disseminated infections can involve liver, spleen, lung, and prostate
- About 50% of clinical cases have bacteremia, and 20% of cases will develop septic shock
- Can occasionally lay latent and reactivate decades after exposure
Prognosis and Complications
- 50% mortality even with high-quality care
Diagnosis
- Culture
- Blood, throat, and urine cultures should be taken from all patients with suspected melioidosis
- Grows on blood agar, MacConkey, etc. (i.e. not a fastidious organism)
- Can use selective colistin or polymyxin B, since it is inherently resistant
- On sheep blood agar, grows as small, smooth, cream-coloured colony with metallic sheen
- May develop a dry and wrinkled appearance after 1 to 2 days of incubation
- MALDI-ToF may misidentify it as Burkholderia thailandensis, and automated biochemical tests may misidentify it as Chromobacterium violaceum
- Other methods
- PCR
- Immunofluorescence and latex agglutination
- Serology (acute/convalescent)
Management
- Intrinsic resistance to many antibiotics, including colistin, primarily using efflux pumps
- Treat with induction followed by eradication therapy
- Induction: ceftazidime, imipenem, or meropenem for 10-14 days
- Eradication: TMP-SMX for 3+ months
- Others: amoxicillin-clavulanic acid
Prevention
Laboratory Safety
- Biosafety risk group 3
- Lab workers can have aerosol exposure if aerosol-generating procedure done outside of a BSC, bite/scratch from infected lab animals, or needlestick/percutaneous exposure
- Those at higher risk include: not wearing proper PPE, diabetes, chronic liver disease, chronic kidney disease, alcohol abuse, chronic corticosteroid use, hematologic malignancy, neutropenia or neutrophil dysfunction, chronic lung disease, thalassemia, or other immunosuppression
- May need prophylaxis in high-risk patients
- TMP-SMX or doxycycline or amoxicillin-clavulanic acid
- TMP-SMX DS 2 tablets (>60 kg) or SS 3 tablets (40-60 kg) or DS 1 tablet (<40 kg) PO bid
- Amoxicillin-clavulanic acid 20/5 mg/kg/dose PO tid
- Duration: 21 days
- Monitor with serology at baseline, weeks 1 2 4 and 6 post-exposure
- Needs to be sent to CDC via NML
References
- ^ Bart J. Currie, Linda Ward, Allen C. Cheng. David Joseph Diemert. The Epidemiology and Clinical Spectrum of Melioidosis: 540 Cases from the 20 Year Darwin Prospective Study. PLoS Neglected Tropical Diseases. 2010;4(11):e900. doi:10.1371/journal.pntd.0000900.
- ^ E. M. Meumann, A. C. Cheng, L. Ward, B. J. Currie. Clinical Features and Epidemiology of Melioidosis Pneumonia: Results From a 21-Year Study and Review of the Literature. Clinical Infectious Diseases. 2011;54(3):362-369. doi:10.1093/cid/cir808.
