Polymerase Chain Reaction (PCR) Assay for Rapid Diagnosis and Its Role in Prevention of Human Brucellosis in Punjab, India

OBJECTIVES: Brucellosis is the most common zoonotic disease that has been diagnosed mainly by serological tests and blood culture to some extent. This study was designed to establish a PCR technique for rapid diagnosis to be used in surveillance activities. METHODS: The purpose of this study was firstly explained to the study population and verbal consent was obtained before sample collection. Peripheral blood was collected from 116 occupationally exposed groups with and without pyrexia of unknown origin from various districts of Punjab. Samples were subjected to blood culture, serological tests and DNA extraction was done using conventional laboratory extraction procedure. A primer pair B4/B5 that amplifies a gene encoding a 31 kDa immunogenic outer membrane protein (bcsp31) of Brucella species was used for PCR amplification. RESULTS: The results showed that 8 (7%) of the cases had positive PCR and the detection threshold of primers used in this study were 715 cfu/ml. PCR results were 51.3% accurate for sensitivity of 12.6% and specificity of 100% using STAT as gold standard. CONCLUSIONS: Early-case reporting is possible by rapid tests like PCR. Thus, PCR is a promising diagnostic tool for routine investigation and surveillance of brucellosis which is the key element for management of prevention and control programmes. But patient condition before testing, optimal clinical specimen, sample volume used, simple and efficient DNA extraction protocol are the points of concern for PCR to be used as a routine test in clinical laboratory practice.