View source for Burkholderia pseudomallei

==Background==

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

===Microbiology===

*Oxidase [[Oxidase::positive]], indole [[Indole::negative]] [[Stain::Gram-negative]] [[Shape::bacillus]] with "'''safety pin'''" appearance (i.e. bipolar staining)
*[[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
*Inherently resistant to [[Polymixin|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 [[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]][[CiteRef::meumann2011cl]]
**[[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 [[Causes::bacteremia]], and 20% of cases will develop [[Causes::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: [[Is treated by::ceftazidime]], [[Is treated by::imipenem]], or [[Is treated by::meropenem]] for 10-14 days
**Eradication: [[Is treated by::TMP-SMX]] for 3+ months
*Others: [[Is treated by::amoxicillin-clavulanic acid]]

==Prevention==

===Laboratory Safety===

*[[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
**[[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
{{DISPLAYTITLE:''Burkholderia pseudomallei''}}
[[Category:Gram-negative bacilli]]