Burkholderia

Question 1

What are the 3 human pathogenic Burkholderia species

Answer 1

•B. cepecia complex (BCC)
•B. mallei
•B. pseudomallei

Question 2

What family is the genus Burkholderia a part of

Answer 2

•Burkholderiaceae
•gram negative, rod bacilli

Question 3

Burkholderia thailandensis

Answer 3

•gram neg, motile bacillus
•soil saprophyte, tropical
•not a human pathogen but opportunistic in immunocompromised

•genetically similar to pseudomallei but differentiated by ability to assimilate L-arabinose

Question 4

BCC

Answer 4

•around 20 species
•found in water, soil, plants, animals, humans
•causes onion rot, plant pathogen
•BCC degrades organic matter, useful in agriculture

Question 5

BCC in cystic fibrosis

Answer 5

•necrotising pneumonia, respiratory failure, bacteremia, cepacia syndrome
•nosocomial
•resistant to aminoglycosides, quinolones, polymyxins, beta lactams

Question 6

What makes BCC pathogenic

Answer 6

•cable pilus for invading epithelium
•biofilm formation

•exopolysaccharide (EPS), cepacian for colonisation and persistence

•intrinsic resistance
•B cepacia epidemic strain marker (BCESM) located on genomic island, genes for metabolism and virulence

Question 7

B mallei

Answer 7

•gram neg, aerobic, non motile, facultative intracellular
•causes glanders
•pathogen of solipeds, horses and donkeys
•nodular lesions in lungs, fever, septicemia, death

Question 8

Glanders

Answer 8

•disease in horses
•mallein can be dropped into horses eyes as a test

Question 9

Glanders

Answer 9

•disease in horses
•mallein can be dropped into horses eyes as a test

Question 10

B mallei as biowarfare

Answer 10

WW1
•glanders spread by Germany to affect Russian horses

WW2
•japan developed glanders as weapon against horses, civilians, POWs

Question 11

B pseudomallei

Answer 11

•melioidosis, ‘glanders like’ disease among morphine addicts
•endemic to SEA and northern Australia
•soil saprophyte

Question 12

Melioidosis

Answer 12

•cutaneous infection
•acute septicemia, chronic infection, latent infection
•risk factors: diabetes, renal disease

Question 13

Melioidosis in Australia

Answer 13

•sheep outbreak, Queensland 1949
•first human case, 32yo diabetic, Townsville 1950
•first NT case was 1960
•2025 FNQ, 26 deaths and 196 cases due to flooding

Question 14

Distinguishing pseudomallei from mallei

Answer 14

•both gram negative bacilli, gram stain shows bipolar safety pin appearance
•both intracellular, mallei is host restricted
•both have 2 chromosomes

•pseudomallei is motile
•mallei is non motile
•pseudomallei has wrinkled appearance on Ashdown agar

Question 15

Burkholderia capsule

Answer 15

•essential for survival and/or replication in macrophages
•reduces opsonisation and phagocytosis
•strains deficient in capsule are highly attenuated

-3-2-O-acetyl 6-deoxy-beta-D-mannose-heptopyranose

Question 16

Burkholderia LPS

Answer 16

•unbranched heteropolymer with repeating d-glucose and l-talose units
•mallei O-antigen is devoid of O-acetyl at 4’ of talose
•O-antigen confers resistance against macrophage killing, prevents killing by complement
•pseudomallei and mallei deficient in O-antigen are attenuated

-3-beta-d-glucopyranose-6-deoxy-alpha-l-talopyranose

Question 17

Burkholderia T3SS

Answer 17

•3 T3SS in pseudomallei
•only T3SS2 and T3SS-3 present in mallei and thailandensis

•T3SS-3 similar to salmonella and shigella
•T3SS-3 required for escape from vacuoles
•required for virulence of pseudomallei and mallei

Question 18

Describe B. pseudomallei lifecycle

Answer 18

1. FliC and PilA, BoaA and BoaB, Sap1- invasion and phagocytosis
2. Sigma factors, catalase, DpsA- phagosome survival
3. T3SS- phagosome escape
4. BimA at one end that promotes Arp2/3 polymerisation of actin cytoskeleton, recruits Ena/VASP
5. T6SS- giant cell formation
6. Host apoptosis and bacterial spread