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Brucella are facultative intracellular gram negative staining bacilli capable of producing the disease "brucellosis" in humans. Human disease likely is acquired by contact with animals infected with the organism (Brucella abortus, Brucella suis, Brucella melitensis, and occasionally Brucella canis) either by direct contact or by ingestion of meat or milk. The signs and symptoms associated with brucellosis may include fever, night sweats, chills, weakness, malaise, headache, and anorexia. The physical examination may reveal lymphadenopathy and hepatosplenomegaly. A definitive diagnosis of brucellosis is made by recovering the organism from blood, fluid (including urine), or tissue specimens.
Diagnosis of brucellosis
Isolation of a Brucella species indicates infection.
Cultures of blood and/or bone marrow are positive in 70% to 90% of acute Brucella infections, but much less so in subacute or chronic infections. In these latter instances, culture yield is highest from the specific tissue involved, or serology may be necessary to establish diagnosis.
Although Brucella are relatively resistant to adverse environmental conditions, excessive delay in the transport of material for culture to the laboratory may result in a lower yield.
Mayo Medical Laboratories does not perform species identification of Brucella; these isolates should be submitted to the State Health Department laboratory.
If a significant delay is expected, specimens should be refrigerated.
Negative (reported as positive or negative)
1. Mandell GL, Bennett JE, Dolin R: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Fourth edition. New York, Churchill Livingstone, 1995, pp 2053-2060
2. Koneman, EW: Miscellaneous Fastidious Gram-Negative Bacilli. In Color Atlas and Textbook of Diagnostic Microbiology. Sixth edition. Philadelphia, Lippincott Williams and Wilkins, 2006, pp 482-491