Brucellosis

Question 1

Brucellosis - organism

Answer 1

Brucella sp = small aerobic intracellular gram-negative coccobacilli

4 species associated with disease:
-B suis
-B abortus [assoc with chronic infections]
-B canis
-B melitensis [most severe form, found in sheep, goats and camels]

Question 2

Brucellosis - epidemiology

Answer 2

Commonest bacterial zoonosis worldwide
500,000 cases per year
Only 10-100 bacteria required to caused infection
Found in Southern Europe, Latin America and Arabian countries
M=F 1:1
Children 20-25%
Rate of familial attack = 50%

Can cause severe clinical disease, fever of unknown origin, HSmegaly, cytopenias

Question 3

Brucellosis - transmission

Answer 3

Zoonosis:
-Consumption of unpasteurised milk/dairy/undercooked meat
-Contact - mucous membrane/skin penetration
-Aerolisation during butchery

Question 4

Brucellosis - incubation period

Answer 4

1 week to months

Question 5

Brucellosis - clinical

Answer 5

Non-specific symptoms
Undulant fever
Night sweats
Headache
Migratory arthralgia [30-50%]
Malaise
Hay-smelling odour
Psychiatric symptoms - depression

Question 6

Brucellosis - complications

Answer 6

Epididymo-orchitis
Endocarditis [main cause of death]
Sacroiliitis
Osteomyelitis
Spondylodiscitis
ITP
Relapse in 10%
Death 2%
Rare <1% - acute neurobrucellosis
Rare <2% - skin manifestations

Question 7

Brucellosis - investigations

Answer 7

Clinical exam - often normal

Targeted exam = arthalgia, HSmegaly, lymphadenopathy

FBC - neutropenia
Less frequent = thrombocytopenia, pancytopenia

Elevated = LFTs, CRP, ESR, LDH

Question 8

Brucellosis - diagnosis

Answer 8

Blood culture [gold standard]:
-Bacteraemia is common but transient
-Gram negative coccobacilli = grey, shiny well defined, non-motile, non-spore forming
-Slow growing

PCR:
-BCSP31
-16S-24S rRNA operon

Serum agglutination ELISA:
-Titres >1:160 [or >1:320 in endemic areas]

Rose Bengal test:
-Detects IgM and IgG
-Not useful for B canis, previous brucellosis, relapses

Radiology:
-Pedro pons sign = erosion of anterior superior aspect of lumbar vertebrae with osteophytosis

Question 9

Brucellosis - treatment

Answer 9

Doxycycline for 45 days
AND
IV streptomycin for 15 days or IV gentamicin for 7-10 days

Alternative oral regimen [high relapse rate] = doxycycline + rifampicin for 45 days

Children and pregnant women = co-trimoxazole with an aminoglycoside or rifampicin

Question 10

Brucellosis - prevention

Answer 10

PPE when working with animals
Leading cause of lab personnel transmitted infection
Pasteurise dairy products and adequately cooking meat products
Live attenuated vaccines for animals [B abortus and B melitensis only] = no human vaccine