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 Salmonella in fresh and processed meats. The technique involved overnight enrichment in BPW, extraction of Salmonella cells onto a polycarbonate membrane, followed by detection of the pathogen using anti-Salmonella monoclonal antibody 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 degrees C), heating (2 or 4 min at 56.9 degrees C), low pH (5 or 3.5) or high salt (2 or 4%). The correlation between traditional plate counts and the rapid count varied widely (r2 = 0.98-0.03), depending on the type and level of stress applied to the cells. The reason for the disparity in results obtained, and the potential application of the method as a diagnostic tool, are discussed.
Duffy
G
G
The National Food Centre, Teagasc, Dublin 15, Ireland. g.duffy@nfc.teagasc.ie
Kilbride
B
B
Sheridan
J J
JJ
Blair
I S
IS
McDowell
D A
DA
D000818:Animals; D002417:Cattle; D002645:Chickens; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D005511:Food Handling; D005615:Freezing; D006361:Heating; D006863:Hydrogen-Ion Concentration; D008460:Meat / Q000382:microbiology*; D009930:Organic Chemicals; D012477:Salmonella enteritidis / Q000254:growth & development / Q000276:immunology / Q000302:isolation & purification*; D012965:Sodium Chloride; D013194:Staining and Labeling / Q000379:methods; D014966:Xanthenes
D005456:Fluorescent Dyes; D009930:Organic Chemicals; C402795:SYTOX Green; D014966:Xanthenes; D012965:Sodium Chloride; C034657:Texas red