Burkholderia pseudomallei: Difference between revisions

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Burkholderia pseudomallei
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==Background==
==Background==

*Also called '''melioidosis''' or '''Whitmore's disease'''

===Microbiology===
===Microbiology===


*[[Oxidase test::Oxidase-positive]], [[Has indole test::indole-negative]] [[Stain::Gram-negative]] [[Has cell shape::bacillus]] with "'''safety pin'''" appearance (i.e. bipolar staining)
*Oxidase [[Oxidase::positive]], indole [[Indole::negative]] [[Stain::Gram-negative]] [[Shape::bacillus]] with "'''safety pin'''" appearance (i.e. bipolar staining)
*[[Has hemolysis pattern::Non-hemolytic]]
*[[Hemolysis::Non-hemolytic]]
*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
*Inherently resistant to [[Polymixin|polymixins]]
*Inherently resistant to [[Polymixin|polymixins]]
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==Clinical Manifestations==
==Clinical Manifestations==


*Incubation period 9 days (range 1 to 21 days)
*Incubation period [[Usual incubation period::9 days]] (range [[Incubation period range::1 to 21 days]])
*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]]
**[[Pneumonia]] (50%)
**[[Pneumonia]] (50%)
**Genitourinary infection (15%)
**Genitourinary infection (15%)
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**Neuro (3-5%)
**Neuro (3-5%)
**Disseminated infections can involve liver, spleen, lung, and prostate
**Disseminated infections can involve liver, spleen, lung, and prostate
*About 50% of clinical cases have bacteremia, and 20% of cases will develop septic shock
*About 50% of clinical cases have [[Causes::bacteremia]], and 20% of cases will develop [[Causes::septic shock]]
*Can occasionally lay latent and reactivate decades after exposure
*Can occasionally lay latent and reactivate decades after exposure

===Prognosis and Complications===

⚫
*50% mortality even with high-quality care


==Diagnosis==
==Diagnosis==
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**Blood, throat, and urine cultures should be taken from ''all'' patients with suspected melioidosis
**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)
**Grows on blood agar, MacConkey, etc. (i.e. ''not'' a fastidious organism)
**Can use selective colistin or polymyxin B
**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
**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
**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]]
*MALDI-ToF is ''not'' reliable for identifying it
*Other methods
*Other methods
**PCR
**PCR
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*Intrinsic resistance to many antibiotics, including [[colistin]], primarily using efflux pumps
*Intrinsic resistance to many antibiotics, including [[colistin]], primarily using efflux pumps
*Treat with induction followed by eradication therapy
*[[Is treated by::Ceftazidime]]
**Induction: [[Is treated by::ceftazidime]], [[Is treated by::imipenem]], or [[Is treated by::meropenem]] for 10-14 days
⚫
*[[Is treated by::Amoxicillin-clavulanic acid]]
*[[Is treated by::TMP-SMX]]
**Eradication: [[Is treated by::TMP-SMX]] for 3+ months
⚫
*Others: [[Is treated by::amoxicillin-clavulanic acid]]


==Biosafety==
==Prevention==


===Laboratory Safety===
*Lab workers can have aerosol exposure

*[[Biosafety risk groups|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 use disorder|alcohol abuse]], chronic [[Corticosteroids|corticosteroid]] use, [[hematologic malignancy]], [[neutropenia]] or neutrophil dysfunction, [[chronic lung disease]], [[thalassemia]], or other [[immunosuppression]]
*May need prophylaxis in high-risk patients
*May need prophylaxis in high-risk patients
**[[TMP-SMX]] or [[doxycycline]] or [[amoxicillin-clavulanic acid]]
**[[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
*Monitor with serology at baseline, weeks 1 2 4 and 6 post-exposure
**Needs to be sent to CDC via NML
**Needs to be sent to CDC via NML

==Prognosis==

⚫
*50% mortality even with high-quality care
{{DISPLAYTITLE:''Burkholderia pseudomallei''}}
{{DISPLAYTITLE:''Burkholderia pseudomallei''}}
[[Category:Gram-negative bacilli]]
[[Category:Gram-negative bacilli]]

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

Prevention

Laboratory Safety

References

  1. ^  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.

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