Journal of Methods Microbiological Journal of Microbiological Methods 39 (1999) 33–43 www.elsevier.com / locate / jmicmeth Isolation and detection of Listeria spp, Salmonella spp and Yersinia spp using a simultaneous enrichment step followed by a surface adhesion immunofluorescent technique a, a a b b * Orla M. Cloak , Geraldine Duffy , J.J. Sheridan , I.S. Blair , D.A. McDowell a The National Food Centre, Teagasc, Dunsinea, Castleknock, Dublin 15, Ireland b University of Ulster, Jordanstown, Newtownabbey, Co. Antrim, Northern Ireland BT37 OQB, UK Received 4 March 1999; received in revised form 12 July 1999; accepted 23 July 1999 Abstract The use of a rapid surface adhesion immunofluorescent (SAIF) technique for the isolation of three pathogens using a single enrichment step from broth and enriched meat cultures was investigated. Buffered peptone water (BPW, 225 ml) was 21 inoculated with Listeria monocytogenes, Salmonella enteritidis and Yersinia enterocolitica to a level of 10 cfu ml and 21 incubated overnight at 308C. Minced beef samples (25 g) were inoculated with the three pathogens to a level of 100 cfu g and incubated overnight at 308C in BPW (225 ml). Pathogens were isolated by surface adhesion to a polycarbonate membrane which was immersed in the enriched culture. The pathogens were detected using membrane counts (rinse and immunofluorescent) and standard plate counts. It was noted that the attachment of the three pathogens to the membrane was considerably enhanced when compared with single inoculum experiments and the reasons and implications of this for the rapid method are discussed. A small selection of naturally contaminated retail samples ( n 5 60) was tested for the presence of L. monocytogenes and S. enteritidis using a simultaneous enrichment step with SAIF detection and a standard cultural 2 method of detection. A good correlation was found between both methods for L. monocytogenes ( r 5 0.91, RSD50.26) and 2 S. enteritidis (r 5 0.89, RSD50.28). This indicates that simultaneous analysis of these two pathogens could be carried out using the SAIF assay.  1999 Published by Elsevier Science B.V. All rights reserved. Keywords: Listeria; SAIF technique; Salmonella; Yersinia 1. Introduction monella spp, Listeria spp and Yersinia spp have been implicated in outbreaks associated with a wide Over the past decade, there has been a marked variety of foods including fish, dairy products, increase in the reported incidence of foodborne vegetables, meat and meat products (Tacket et al., illness due to the bacterial contamination of foods 1984; Linnan et al., 1988; Bean and Griffin, 1990; (Todd, 1994). Among the pathogenic bacteria, Sal- McLauchlin et al., 1991). Traditional cultural methods used to isolate and identify these pathogens are slow, taking up to 4–5 *Corresponding author. Tel.: 1353-1-805-9500; fax: 1353-1- days to obtain a presumptive positive result and a 805-9550. E-mail address: o.cloak@nfc.teagasc.ie (O.M. Cloak) further 1–2 days to confirm and speciate organisms 0167-7012 / 99 / $ – see front matter  1999 Published by Elsevier Science B.V. All rights reserved. PII: S0167-7012(99)00095-0