Chemiluminescent optical fiber immunosensor detection of Brucella cells presenting smooth-A antigen

Brucellosis is a worldwide distributed zoonotic re-emerging disease, causing abortions in domesticated animals and Malta fever in humans. Currently, the gold standard for confirmation of the existence of the causative agent genus Brucella is the isolation of the bacteria from body or liquid samples, whereas standard serological tests are used for diagnosis. The need for a rapid point of care identification of Brucella organisms has led us to develop a novel chemiluminescent optical fiber immunosensor. The immunosensor based on a conventional enzyme linked immunoassay (ELISA) technique was implemented on optical fibers and its performance was compared to the standard ELISA method. We show that depending on the detecting antibodies used specificity of the assay is achieved. Brucella cells presenting smooth-A O-chain determinant were detected at a minimal protein concentration of 1.098 ng/ml, correlating to 305 cfu/ml, while smooth-M O-chain cells, rough cells and two gram-negative bacteria other than Brucella sp. produced negative results, confirming the high specificity of the technique.