Exposure of hospital personnel to Brucella melitensis and occurrence of laboratory-acquired disease in an endemic area.

In 1997, 7 cases of laboratory-acquired Brucella melitensis infections were detected among the hospital personnel of a medical centre serving an endemic area in southern Israel. Although the onset of symptoms in 6 of the 7 patients occurred during a 2-week period, suggesting a point source exposure, biotype analysis showed that the outbreak was caused by 3 different B. melitensis serovars, indicating multiple exposures. Review of the laboratory records showed that during 1997, the microorganism was recovered from 146 blood and synovial fluid cultures, and that during the 2 months in which the laboratory-acquired cases occurred (April and June), 53 of 530 positive aerobic blood culture bottles (10.0%) grew B. melitensis. The epidemiological investigation did not reveal the source of the outbreak, and no noticeable breaches in laboratory safety practices could be demonstrated. It is concluded that in areas endemic for brucellosis, hospital personnel are frequently exposed to Brucella microorganisms. Under these circumstances, significant morbidity may occur despite observance of recommended safety practices. Biotyping of Brucella isolates may contribute to the elucidation of complex epidemiological situations.