RAPID ASSAY FOR PATHOGENIC SALMONELLA ORGANISMS BY IMMUNOFLUORESCENCE FLOW-CYTOMETRY

Multi-parameter dow cytometry was investigated for the rapid detection of specific serotypes of salmonellas (S. typhimurium and S. montevideo) labelled with fluorescent monoclonal antibodies, both in pure culture and in a typical food matrix (full-fat milk). In all cases, the method was accurate: to levels of below 10(4) target cells per mi for a total assay time of about 30min. After 6h non-selective enrichment in the presence: of a 10000-fold excess of competing micro-organisms (Escherichia coli) the corresponding detection limit was about 20 cells ml(-1). These results suggest that now cytometry has significant potential for the detection of pathogenic micro-organisms in the food industry.