A membrane-immunofluorescent-viability staining technique for the detection of Salmonella spp. from fresh and processed meat samples

A direct staining technique was investigated for the detection of viable Sa lmonella in fresh and processed meats. The technique involved overnight enr ichment in BPW, extraction of Salmonella cells onto a polycarbonate membran e, followed by detection of the pathogen using anti-Salmonella monoclonal a ntibody coupled with an antibody linked-fluorescent stain (Texas Red) and a viability stain (Sytox Green). The technique was applied to the detection of Salm. enteritidis inoculated into broth culture or minced beef and then subjected to a variety of stresses including freezing (- 20 degreesC), heat ing (2 or 4 min at 56.9 degreesC), low pH (5 or 3.5) or high salt (2 or 4%) . The correlation between traditional plate counts and the rapid count vari ed widely (r(2) = 0.98-0.03), depending on the type and level of stress app lied to the cells. The reason for the disparity in results obtained, and th e potential application of the method as a diagnostic tool, are discussed.