Burkholderia pseudomallei: Difference between revisions
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Burkholderia pseudomallei
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===Microbiology=== |
===Microbiology=== |
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*[[Oxidase test::Oxidase-positive]], [[Has indole test::indole-negative]] Stain::Gram-negative]] [[Has cell shape::bacillus]] with "'''safety pin'''" appearance |
*[[Oxidase test::Oxidase-positive]], [[Has indole test::indole-negative]] Stain::Gram-negative]] [[Has cell shape::bacillus]] with "'''safety pin'''" appearance (i.e. bipolar staining) |
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*[[Has hemolysis pattern::Non-hemolytic]] |
*[[Has hemolysis pattern::Non-hemolytic]] |
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*Colonies |
*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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*Inherently resistant to [[Polymixin|polymixins]] |
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===Epidemiology=== |
===Epidemiology=== |
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*Incubation period 9 days (range 1 to 21 days) |
*Incubation period 9 days (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 |
*Presentations can vary from asymptomatic, skin ulcers, abscesses, latent infection, chronic pneumonia (similar to TB), or fulminant shock[[CiteRef::diemert2010th]] |
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**Pneumonia (50%) |
**[[Pneumonia]] (50%) |
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** |
**Genitourinary infection (15%) |
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**Skin (15%) |
**Skin infection (15%) |
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**Primary bacteremia (10%) |
**Primary bacteremia (10%) |
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**Septic arthritis/OM (3-5%) |
**Septic arthritis/OM (3-5%) |
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**Neuro (3-5%) |
**Neuro (3-5%) |
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*About |
*About 50% of clinical cases have bacteremia, and 20% of cases will develop septic shock |
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*Can occasionally lay latent and reactivate decades after exposure |
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==Diagnosis== |
==Diagnosis== |
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*Culture |
*Culture |
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**Blood, throat, and urine cultures from all patients with suspected melioidosis |
**Blood, throat, and urine cultures should be taken from ''all'' patients with suspected melioidosis |
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**Grows on blood agar, MacConkey, etc. (i.e. ''not'' a fastidious organism) |
**Grows on blood agar, MacConkey, etc. (i.e. ''not'' a fastidious organism) |
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**Can use selective colistin or polymyxin B |
**Can use selective colistin or polymyxin B |
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==Management== |
==Management== |
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*Intrinsic resistance to many antibiotics, |
*Intrinsic resistance to many antibiotics, including [[colistin]], primarily using efflux pumps |
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*[[Is treated by::Ceftazidime]] |
*[[Is treated by::Ceftazidime]] |
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*[[Is treated by::Amoxicillin-clavulanic acid]] |
*[[Is treated by::Amoxicillin-clavulanic acid]] |
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**Needs to be sent to CDC via NML |
**Needs to be sent to CDC via NML |
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== Prognosis == |
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* 50% mortality even with high-quality care |
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{{DISPLAYTITLE:''Burkholderia pseudomallei''}} |
{{DISPLAYTITLE:''Burkholderia pseudomallei''}} |
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[[Category:Gram-negative bacilli]] |
[[Category:Gram-negative bacilli]] |
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Revision as of 02:13, 22 July 2020
Background
Microbiology
- Oxidase-positive, indole-negative Stain::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 shock1
- Pneumonia (50%)
- Genitourinary infection (15%)
- Skin infection (15%)
- Primary bacteremia (10%)
- Septic arthritis/OM (3-5%)
- Neuro (3-5%)
- About 50% of clinical cases have bacteremia, and 20% of cases will develop septic shock
- Can occasionally lay latent and reactivate decades after exposure
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
- 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 is not reliable for identifying it
- Other methods
- PCR
- Immunofluorescence and latex agglutination
- Serology (acute/convalescent)
Management
- Intrinsic resistance to many antibiotics, including colistin, primarily using efflux pumps
- Ceftazidime
- Amoxicillin-clavulanic acid
- TMP-SMX
Biosafety
- Lab workers can have aerosol exposure
- May need prophylaxis in high-risk patients
- Monitor with serology at baseline, weeks 1 2 4 and 6 post-exposure
- Needs to be sent to CDC via NML
Prognosis
- 50% mortality even with high-quality care
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.
