Laboratory diagnostics of Brucella infection – risk of laboratory infection

Abstract number: 1134_01_181

Steinbakk M., Evjen N., Tjade T., Hellum K.B., Jonassen T.O.


Brucellosis is a rare disease in Norway. Brucellosis is caused by Brucella, a small, non-motile, Gram-negative aerobic coccobacillus. The genus Brucella comprises the six species B. melitensis, B. abortus, B. suis, B. ovis, B. neotomae and B. canis. Even though Brucella is divided in different species based on host specificity and biochemical characteristics, they may be regarded as one species based on DNA sequence information. Here we present a case of laboratory-acquired brucellosis.


Brucella is oxydase- and catalase-positive, and how fast they become urease-positive is used as a phenotypic criterion of differentiation. Brucella grows slowly in Bactec aerobic blood culture medium, but more than 95% of the positive cultures are positive in less than seven days. In subculture Brucella grows on blood agar in less than two days. When conventional methods are insufficient for identification of a bacterium, sequencing of the 16S rDNA will give the correct genus and often also the species.


Case 1 is a 54-year-old man who was admitted to the Department of Neurology after one day of acute lumbago ultimo July 2003. Seven days later the patient in addition to severe back pain got fever and was transferred to the Department of Infectious Diseases. After three days small Gram-negative rods grew out in aerobic blood cultures. The microbe was identified as Brucella sp based on standard bacteriological techniques and sequencing of 16S rDNA. The patient had not been abroad the last two years, and had no known exposure to Brucella. Case 2 is a 30-year-old woman who had worked with the blood culture isolate from case 1. From January 10th 2004 she had undulating fever, initially regarded as an influenza-like illness. She was admitted to the Department of Infectious Diseases ultimo January 2004 under the diagnosis: ‘Fever of unknown origin, Brucella?’ Aerobic blood culture taken at the time of admission was positive after three days of incubation, and also in this case Brucella sp was identified. The patient had no other risk of brucellosis than her work in the laboratory five months earlier.


During bacteriological identification of the blood culture isolate from case 1, parts of the identification work (catalase reaction) was done on open bench. After the identification of this isolate as Brucella, all bacteriological diagnostic work that can produce infectious aerosol, are done in biological safety cabinets.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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