Detection and isolation of Salmonella from naturally contaminated alfalfa seeds following an outbreak investigation

Naturally contaminated alfalfa seeds, epidemiologically linked to foodborne disease outbreaks in Oregon and British Columbia, were tested for the pres ence of Salmonella. Ten sample units from the suspected lot were sprouted a nd grown for 4 days. After enrichment of the grown sprouts, an enzyme immun oassay (EIA) and culture method (modified procedure of the Food and Drug Ad ministration Bacteriological Analytical Manual) were used for the detection and isolation of Salmonella. Four of the 10 sample units were positive wit h the ELA; however, 5 of the 10 sample units were culture positive (four we re positive for Salmonella serotype Newport and a fifth was positive for Sa lmonella serotype Albany and serotype Schwarzengrund). The positive alfalfa seed sample units were further tested after shredding, soaking, and washin g before culturing. Results suggest that sprouting and shredding methods ma y yield greater detection and recovery rates of Salmonella, but more resear ch with a larger sample size is warranted.