Burkholderia pseudomallei: Difference between revisions
From IDWiki
Burkholderia pseudomallei
(→) |
m (Text replacement - " Stain::Gram" to " [[Stain::Gram") |
||
| Line 2: | Line 2: | ||
===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 test::Oxidase-positive]], [[Has indole test::indole-negative]] [[Stain::Gram-negative]] [[Has cell shape::bacillus]] with "'''safety pin'''" appearance (i.e. bipolar staining) |
||
*[[Has hemolysis pattern::Non-hemolytic]] |
*[[Has hemolysis pattern::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 |
||
Revision as of 00:51, 29 July 2020
Background
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 shock1
- 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
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.
