Isolation of Brucella from blood culture of hospitalized brucellosis patients

Brucellosis is a zoonotic disease that is endemic in Iran. Appropriate and rapid diagnosis has a vital role in public health improvement. Low isolation rate of the organism has reported frequently in various reports. The present study was conducted to determine the isolation rate of organism in culture from collected specimens of hospitalized patients who were not under antibiotic therapy. Meanwhile, comparing the direct inoculation to biphasic media with lysis method was also determined. Twenty-five hospitalized brucellosis patients diagnosed on the basis of clinical manifestations and positive serologic tests were included. Blood samples were provided and cultured either as direct inoculation into biphasic media or lysis method by washing with distilled water before culture on solid media. Brucella was isolated in 4 samples (16%). Further studies revealed all these four cases to be B. melitensis. Washing method did not differ in isolation rate with direct inoculation; however, Brucella was isolated in a shorter period in washing method. Higher isolation rate when compared with prior studies indicates an appropriate sampling time and technique, rapid inoculation to the media, and the lack of antibiotic therapy before sampling. Washing method has the preference of shorter isolation time to direct inoculation; however, it is faced with a higher risk of contamination.