Brucella

Causes Brucellosis (undulant fever)

Characteristics/Epidemiology

Primarily animal pathogen

Localise in reproductive organs

Causes sterility and abortion in animal.

Pathogenesis/Transmission

Transmission

Transmission to human - direct contact with infected reproductive tissues (rarely, meat) or ingestion of unpasteurised milk or milk products.

Pathogenesis

Enters through cuts and abrasions in skin or through GI tract or through inhalation.

Organisms are carried to and multiply in reticuloendothelial system.

Survive and multiply inside phagocytes

Lipopolysaccharide - major virulence factor/major cell wall antigen

Clinical significance

Incubation - 5 days to several months (typically several weeks)

Symptoms - nonspecific, flu-like

• Malaise
• Fever (undulant - repeatedly rise then fall)
• Sweats
• Anorexia
• GI symptoms
• Headache
• Back pains
• ?Depression

Onset can be abrupt or insidious.

Subclinical infections can occur.

Laboratory identification

Features

Aerobic, facultative

Intracellular parasite

Unencapsulated

Diagnostic test

Serologic tests for agglutinating antibodies

Culture - require 1 month before declared negative

Treatment

First line: Doxycycline and gentamicin (or streptomycin)

Prolonged treatment - 6 weeks necessary to prevent relapse and complication.

 

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