Assay of Salmonella in enrichment cultures of foods, feeds and environmental samples by the polymyxin-cloth enzyme immunoassay.
A variety of foods, animal feeds and environmental samples were analyzed for the presence of Salmonella using the polymyxin-cloth enzyme immunoassay (p-CEIA) system. Salmonella lipopolysaccharide (LPS) antigens were captured from test samples on polymyxin-coated polyester cloth, followed by immunoenzymatic detection of bound antigens using a monoclonal antibody recognizing an LPS common core oligosaccharide. Dairy and egg products, animal feeds and environmental samples from food processing plants were pre-enriched for 24 h, followed by selective enrichment for a further 24 h in either tetrathionate brilliant green (TBG), selenite cystine (SC) or brain-heart infusion broth containing 0.5% yeast extract, 0.5% cholate and 0.3% selenite (BYCS). The samples were assayed by the p-CEIA after each stage of enrichment. After selective enrichment, the p-CEIA gave results which were in complete agreement with the standard culture technique in the analysis of all foods examined. On the other hand, a combination of selective enrichment and the p-CEIA out-performed the Modified Semi-Solid Rappaport Vassiliadis (MSRV) method in screening pre-enrichment cultures of feeds and environmental samples. Use of the new selective medium BYCS prior to performing the p-CEIA gave the highest recovery of Salmonella from feeds and environmental samples.
Blais
B W
BW
Laboratory Services Division, Canadian Food Inspection Agency, Ottawa, Ontario, Canada.
Chan
P L
PL
Phillippe
L M
LM
Brooks
B W
BW
Hayashi
S
S
Yamazaki
H
H
D000821:Animal Feed / Q000382:microbiology*; D000942:Antigens, Bacterial / Q000032:analysis; D004783:Environmental Microbiology; D005516:Food Microbiology; D007124:Immunoenzyme Techniques; D011113:Polymyxins; D012475:Salmonella / Q000302:isolation & purification*
D000942:Antigens, Bacterial; D011113:Polymyxins