Brucella

Categorization
Cell Wall: Gram Negative Shape: Rod
Life Cyle: Facultative Intracellular Metabolism: Obligate Aerobe
Transmission
  • Brucella species are zoonotic organisms whose natural reservoir are a variety of domesticated mammals including pigs, dogs, cows, and sheep. Transmission to humans may occur occupationally in those handling contaminated animals and their meats via inhalation of respiratory droplets, contact with abrased skin, or by ingestion of contaminated food, especially unpasteurized dairy products.
Pathogenesis
  • Presumably, Brucella are phagocytosed at their point of entry, be it the GI tract, lung, or skin, by resident macrophages. They evade phagocytic cell death and can multiply within the macrophage phagosome, in keeping with their facultative intracellular nature. Infected macrophages then disseminate the infection initially to the regional lymph nodes and then hematogenously to a wide variety of other organs where the organisms can establish infection.
Clinical Consequences
  • Brucellosis is initially characterized by an "Undulant Fever" which tends to rise in the afternoon and drop at night, resulting in night sweats. Along with fever, a variety of other constitutional symptoms such as fatigue and myalgias occur. In a substantial number of patients, deep back pain is a herald of vertebral osteomyelitis. In many patients a chronic infection is established which is characterized by waning symptoms that periodically relapse.
Treatment
  • Streptomycin together with doxycycline