Background: Brucellosis is a zoonotic disease, endemic in many parts of the world especially the Middle East. It is an important health problem in Egypt. Since the clinical symptoms of human brucellosis are protean and nonspecific, laboratory confirmation by isolation of organism or detection of specific antibodies is necessary for the diagnosis. The objective of this study is to validate a PCR technique for the detection of brucella infection. So, we can differentiate between the true and current infections by this organism from the falsely positive antibodies produced from previous or treated infections.
Methods: This study comprised 97 patients (74 males and 23 females) from different ages experienced the clinical symptoms of brucellosis. This study was carried out at Mansoura University Hospitals. The blood samples collected were subjected to culture, Brucella test and PCR targeting the gene encoding a 31-kDa Brucella abortus (BCSP31).
Results: PCR standardized for the gene encoding a 31-kDa Brucella abortus BCSP31 gene result in specific amplicon of 223-bp. In positive PCR cases of brucella (total 14), a single band of 223bp corresponding to BCSP31 gene was obtained. The PCR assay was found to be highly specific and the true positive brucellosis cases (n = 6) are positive of brucella test, blood culture and /or PCR. PCR was sensitive than blood culture for diagnosis of brucellosis since the sensitivity and specificity of PCR are 87.5% and 98.73% respectively and the sensitivity and specificity of blood culture are 84.62% and 96.15% respectively. There was a significant correlation between brucella titre and blood culture (p = 0.001) in patients with brucella. Furthermore, there was a significant correlation between brucella titre and PCR (p = 0.001) in patients with brucella.
Conclusion: We recommend using PCR as an alternative to blood culture for diagnosis of acute brucellosis. Further studies are required to compare different techniques. We also recommend performance of a large scale study to test this PCR technique for screening for brucellosis in Egypt.
Key words: Brucellosis, Brucella test, blood culture, PCR.