Isolation of brucella melitensis and brucella abortus from brucellosis patients by conventional culture method and polymerase chain reaction technique

ABSTRACT

Isolation of B. melitensis and B. abortus from brucellosis patients by application of conventional culture and PCR methods and comparison of sensitivity of both techniques in diagnosis of human brucellosis. Infectious diseases Ward, Ahwaz University's hospitals over a period of 9 months [September 2003 to May 2004]. A total of 30 peripheral blood samples were collected from patients with brucellosis referred to infectious Diseases Unit of Ahwaz University's hospitals. The samples were inoculated into Castaneda medium and after 7-30 days, the isolated colonies were identified by inoculation into brucella agar containing thionine and fuschin and by performance of biochemical tests. DNA was extracted from colonies and serum samples and examined by PCR involving specific primers for B. melitensis and B. abortus based on IS 711 in the brucella chromosome. We identified 8 isolates of B. melitensis using culture and biochemical methods. When PCR technique was applied to serum samples, 28 cases were positive for B. melitensis and we were able to isolate more cases compared to culture method and the difference was significant [P<0.05]. The sensitivities of culture and PCR in this study were determined as 26.6% and 93.3% respectively. Neither of examined cultures or sera subjected to PCR were positive for B. abortus. The results of present study showed that PCR assay is a rapid and sensitive technique for diagnosis of brucellosis compared to culture method. However it is more valuable when coupled with conventional methods: