Bacteria 6 (gram -ve): Brucellosis

Question 1

Which type of bacterium is brucella?

Answer 1

Intracellular Gram-negative coccobacillus

Question 2

What species of brucella are there?

Answer 2

Question 3

How do humans acquire the infection?

Answer 3

Long incubation period - weeks to months

Over 500,000 people/yr infected, mostly in agrarian societies. Animal public health control key

Question 4

What are the symptoms of brucellosis (in humans and in animals)?

Answer 4

Humans (rarely fatal):

Recurrent prolonged bouts of fever

Specific to brucellosis: focal MSK symptoms - in endemic areas feverish personw ith difficulty walkin = brucellosis until proven otherwise

Sweating (it is a ddx in any person with TB)

Neuropsychiatric symptoms such as depression

Animals:

Orchitis, epidydymitis, infertility and abortion

Question 5

How quickly do symptoms of brucellosis come on?

Answer 5

B. melitensis -> more acute

B. abortus -> more insidious

B. suis -> acute, complicated by focal deep tissue abscesses

Question 6

How do you diagnose brucellosis?

Answer 6

Bloods: low WCC, low plts, deranged LFTs

Blood Culture: most reliable method but have to culture for up to 6 weeks, best for B. melitensis

Serology: old test called Wright’s standard agglutination test

PCR

Xray changes are usually late, CSF can show lymphocytosis and histology may show non-caseating granuloma

Bottom line: Diagnostic “cut-off’s for serological tests need to be set higher in endemic areas than in non-endemic areas, Serologic testing is the most commonly used method of diagnosing brucellosis. , Blood culture is the most reliable method of confirming the diagnosis

Question 7

How do you treat brucellosis?

Answer 7

At least two anti-microbials one of which is normally doxycyline

Question 8

How do you prevent brucellosis?

Answer 8

Currently no vaccine in humans

Question 9

How do you differentiate between TB and brucellosis?

Answer 9

TB - caseating

Brucellosis - non-caseating