Comparison of Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) and Agglutination Assays in Diagnosis of Brucellosis in Golestan Province, North of Iran

Abstract

Introduction: Brucellosis is one of the most common zoonotic infections worldwide. The clinical symptoms of brucellosis are similar to a wide range of diseases; hence, reliable diagnostic and laboratory methods are required to identify the causative agent. Iran is an endemic region of brucellosis, and many patients are misdiagnosed due to the nature of the infection. In this study, we aimed to evaluate and compare the use of the conventional Wright test and quantitative polymerase chain reaction (qPCR) for the diagnosis of brucellosis. Methods: Diagnosis of brucellosis was performed using serological tests and PCR amplification of a gene encoding 31-kDa immunogenic Brucella abortus protein (BCSP31). Data were analyzed using the Chi-square test. Results: Brucellosis was diagnosed in 45 (69.23%) and 22 (38.8%) patients using the Wright test and qRT-PCR, respectively. The results of Wright and qRT-PCR assays were consistent in patients with negative results (90%). Moreover, qRT-PCR detected brucellosis in 25% of patients with Wright test titers <1/160, while 55.2% of the patients were positive with titers ≥1/160. No significant association was detected between positive PCR results and age, gender, and clinical symptoms. Conclusion: qRT-PCR showed a reliable diagnostic method capable of detecting the infection in suspected individuals with negative Wright results or with Wright test titers <1/160. Also, the positive qRT-PCR assays were in agreement with the Wright test titer. Regarding the financial and availability issues as well as technical problems, the agglutination test remains the preferred method in Iran.

Comparison of the Polymerase Chain Reaction Method with Serological Tests in the Diagnosis of Human Brucellosis

“…Differences in the sensitivity and specificity of PCR samples in studies can be due to differences in PCR kits, the disease stage, and the method of DNA extraction from serum or whole blood samples of patients. False negatives in the PCR sample can be attributed to technical errors, the inefficiency of the chemicals used, low DNA content in the serum sample, and previous use of antibiotics (17,(28)(29)(30). The current study showed that the PCR method has high accuracy, specificity, and sensitivity, promoting the importance of using this method as a reliable early diagnostic test in human brucellosis, especially in suspected patients with seronegative tests.…”