Comparison of Methods for Determining the Presence of Escherichia coli O157:H7 in Apple Juice
Abstract:Six methods were compared for detection of three strains of Escherichia coli O157:H7 in enrichments of inoculated apple juice. Juice was inoculated at levels varying from 0.1 to 100 CFU/ml and centrifuged after overnight storage at 4°C, and pellets were incubated at 37°C in nonselective enrichment broth. At hourly intervals between 5 and 10 h and at 24 h, the enrichments were tested for E. coli O157:H7 by direct fluorescent antibody (DFA), antibody-direct epifluorescent filter technique (Ab-DEFT), direct selective plating on sorbitol MacConkey agar (SMA), immunomagnetic separation coupled to either selective plating (IMS-SMA) or the polymerase chain reaction (IMS-PCR), and flow cytometry (FC). The most consistent detection of 0.1 CFU/ml of the slowest growing strain of the pathogen was provided by the IMS-SMA and IMS-PCR after 8 h of enrichment. The time required for detection at the level of 0.1 CFU/ml for each assay was Ab-DEFT, 11 h; IMS-PCR, 16 h; FC, 24 h; IMS-SMA, 32 h; and SMA, 48 h. Absolute detection limits (without enrichment) were: IMS-PCR, 103 CFU/ml; Ab-DEFT and IMS-SMA, 104 CFU/ml; SMA, 105 CFU/ml; and DFA, 106 CFU/ml. Recovery of the pathogen (10 CFU/ml) in apple juice after 28 days of 4°C storage was possible by means of an 8-h enrichment and Ab-DEFT, IMS-PCR, or IMS-SMA.
Document Type: Research Article
Affiliations: 1: U.S. Food and Drug Administration, National Center for Food Safety and Technology, Summit-Argo, Illinois 60501, USA 2: Center for Food Safety and Applied Nutrition, Laurel, Maryland 20708, USA
Publication date: November 1, 1998
- IAFP Members with personal subscriptions to JFP Online: To access full-text JFP or JMFT articles, you must sign-in in the upper-right corner using your Ingenta sign-in details (your IAFP Member Login does not apply to this website). The Journal of Food Protection (JFP) is a refereed monthly publication. Each issue contains scientific research and authoritative review articles reporting on a variety of topics in food science pertaining to food safety and quality. The Journal is internationally recognized as the leading publication in the field of food microbiology with a readership exceeding 11,000 scientists from 70 countries. The Journal of Food Protection is indexed in Index Medicus, Current Contents, BIOSIS, PubMed, Medline, and many others.
Print and online subscriptions are available to IAFP Members and institutional subscribers. IAFP Members with a subscription to JFP Online will have access to all available JFP and JMFT content. Online visitors who are not IAFP Members or journal subscribers will be charged on a pay-per-view basis. Membership and subscription information is available at www.foodprotection.org.
- Information for Authors
- Submit a Paper
- Subscribe to this Title
- Membership Information
- Information for Advertisers
- Ingenta Connect is not responsible for the content or availability of external websites