Detection of Brucella militensis in the Serum of Patients Suspected of Brucellosis by the Omp31 Gene Amplification, Compared to the Serological Diagnostic Tests

Background and Objectives: Brucellosis is one of the most common infectious diseases with a global spread. It has a high prevalence in Iran. This study aims to diagnose brucellosis caused by Brucella melitensis in the serum of patients by the amplification of omp31 gene, compared to the serological tests. Methods: Blood samples were collected from 200 people suspected of brucellosis. The samples were evaluated by serological tests including Rose Bengal test, Wright test, Coombs-Wright test, gel agglutination test, and 2-mercaptoethanol (2ME) test. DNA extraction was done by the phenol/chloroform extraction method. Molecular detection with polymerase chain reaction (PCR) method was done using the specific primers of the Omp31 gene. Data were analyzed in SPSS software, version 23 using the analysis of variance. Results: Of 200 patients, 122 were female and 78 were male with a mean age of 45.17±17.43 years. The results of PCR test for the omp31 gene were positive in 14.5% of cases, which was consistent with the results of serological tests (13.8%). The sensitivity of Wright, Coombs-Wright, 2ME, and gel agglutination tests, compared to PCR, was 89.7, 75.9, 55.2 and 55.2%, respectively. Most of the affected people were housekeepers (41.5%) and urban residents (75.5%). Muscle pain (68%) and leg pain (62.3%) were the most common symptoms. Consumption of non-pasteurized dairy products was the highest risk factor (17%). Conclusion: The diagnosis of brucellosis by the omp31 gene amplification has higher sensitivity and accuracy compared to the serological tests. Considering the importance of rapid and timely diagnosis of brucellosis to control its clinical complications, the molecular diagnosis method is recommended as a diagnostic method.