Small gram- negative coco bacillary organism(0.5-0.7um by 0.6-1.5 um)In smear they occurs singly , in pairs or in short chain.Described as having the appearance of sandNon-motile, strictly aerobic and catalase and usually oxidase positive organisms.Growth is often enhanced by the persence of 5% to 10% CO2 and requires complex media.
Human pathogens1.Brucella melintensis2.Brucia abortus3.Brucella suis4.Brucella canisClinical manifestation and pathogenesisBrucella spp. Are intracellular parasite that infect a wide range of animal species and have also been found in some insect and ticks.
Human become infected by:-1. Inhaling the organisms.2. Direct infection with infected materials including - Animal carcasses - Fetal membrane - vaginal discharges - fetuses - skin or mucous membrane - ingestion of unpasturized milk or milk products from infected animals
A common risk factor is consumption of imported cheese made from unpasturized goat’s milkLocal adenopathy often occurs with dissemination and secondary localization in the RES (reticulo endothelial system) and formation of granulomas in the liver, spleen, bone, genitourinary tract, lungs and soft tissue. *Adenopathy (enlargement of glandular tissue specially lymph nodes)
Organisms may be seen within phagocytesSigns and symptoms are often variable and non-specific, with chills, fever, sweats and anorexia.The fever is characteristically (dirulant) undulant.
Most often recovered from blood and bone marrow and less often from material obtained from spleen and liver abcesses. They grow on standard laboratory media. - brucella - blood - chocolate - trypticase soy agar Some strains will grow on mac conkey agar. Can be done serologically (1: 160) Recent brucellosis when a four fold or greater rise in titer occurs during the first month or two of illness.
TreatmentCombination of- tetracycline- Aminoglycosidase- rifampin- trimetheoprin sulfamethoxazole (for prolonged period of time).