Comparison of multiplex real-time polymerase chain reaction with serological tests and culture for diagnosing human brucellosis

Abstract

Objective: Brucellosis is a zoonotic disease with various clinical presentations and early diagnosis is crucial to avoid severe complications. Due to limitations of conventional diagnostic methods, polymerase chain reaction (PCR) based approaches have gained importance in diagnosis.We aimed to evaluate diagnostic value of multiplex real time-PCR (mRT-PCR) in serum samples collected from brucellosis suspected patients by comparision sensitivity of mRT-PCR with those of conventional diagnostic methods. Material and Methods: A total of 249 serum samples collected from the suspected brucellosis patients admitted to the hospitals in three different provinces were analyzed by serological tests, culture and mRT-PCR. In laboratories of the participating hospital, serum samples were tested for the Brucella specific antibody by commercial serological kits including standart tube agglutination test (STAT), Coombs’ test, and immunocapture test (ICT). Blood culture was performed for 153 of the patients in the participating hospital. All serum samples were analyzed for the presence of Brucella DNA by mRT-PCR. Results: According to laboratory test results, 215 of the 249 suspected cases having comparible clinical data were identified as brucellosis cases. Of the 215 brucellosis cases, 36 were diagnosed as definitive cases, the remaning 179 patients were presumptive cases. Sensitivity of mRT-PCR in the samples that were positive by ICT, STAT, Coombs’ test, and blood culture was 70.2%, 77.3%, 83%, and 97.2%, respectively. By using mRT-PCR, additional 17 suspected patients were diagnosed as presumptive cases. Among the mRT-PCR positive serum samples, Brucella abortus was detected in 3 samples (1.9%), the remaining 156 samples (98.1%) had B. melitensis DNA. Conclusion: Our results indicate that mRT-PCR can be considered a useful diagnostic tool in patients who have negative serologic test results, and in detection of Brucella species. Keywords: Brucellosis, Multiplex real-time PCR, Serological diagnosis, Culture