Detection of Brucella species by PCR from human blood

Abstract

BACKGROUND: Diagnosis of brucellosis remains a challenge and centers on the isolation of an organism and serologic test results. Molecular methods have been developed for the detection and identification of Brucella to improve diagnostic capabilities.

OBJECTIVES:

1. Detection of Brucella directly from blood using PCR  and culture methods
2. Serodiagnosis of brucellosis based on Standard agglutination test (SAT)
3. Comparison between Culture, Serological and PCR  Methods  with blood culture as the gold standard

STUDY DESIGN: Hospital-based prospective study.

PARTICIPANTS:  100 blood samples from patients with clinical suspicion of Brucellosis.  

METHODS:  Blood collected were subjected for culture, serological testing, and DNA extraction. DNA amplification was done based on genus-specific PCR. SAT was performed using the Tube agglutination Test.

RESULTS: Of a total of 100 blood samples, PCR was performed in 100 samples, SAT in 94, and blood culture only in 36 samples. 29(29%) of PCR-tested samples were positive for Brucella spp. Of the total 94 SAT-tested samples, 44%  were positive for titers with a cutoff of ≥ 1:160. Of the total 36 blood culture tested samples,10(27%) showed growth of Brucella melitensis. Compared to blood culture, sensitivity and specificity of PCR calculated was 60% and 73% respectively and sensitivity and specificity of SAT calculated was 96% and 73% respectively.

CONCLUSIONS:  PCR was found to be Rapid, Sensitive, and specific test for the diagnosis of Brucellosis.

Implications: PCR can be used routinely as an adjunct to conventional methods available in laboratory for diagnosis of brucellosis