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An Allelotyping PCR for Identifying Salmonella enterica serovars Enteritidis, Hadar, Heidelberg, and Typhimurium
Published on: July 22, 2011
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Salmonella Enteritidis phage type 21 outbreak in Austria, 2005.
D Schmid1, S Schandl1, A M Pichler1
1Österreichische Agentur für Gesundheit und Ernährungssicherheit, Vienna, Austria.
Summary
A Salmonella Enteritidis outbreak sickened 85 people at an Austrian fair. Contaminated eggs, used in a potato salad, were identified as the likely source, highlighting risks in traditional food preparation.
Area of Science:
- Foodborne illness epidemiology
- Microbial food safety
Background:
- An annual traditional fair in Austria experienced an outbreak of gastroenteritis.
- The outbreak occurred in May 2005 and was linked to Salmonella Enteritidis PT 21.
Purpose of the Study:
- To investigate the outbreak of gastroenteritis.
- To determine the extent of the outbreak and identify risk factors.
- To identify the source and transmission routes of Salmonella Enteritidis PT 21.
Main Methods:
- Descriptive and analytical epidemiological investigations were conducted.
- Case criteria were established, and a cohort study was performed.
- Stool specimens were collected for salmonella testing.
- Molecular subtyping (pulsed-field gel electrophoresis) was used to compare isolates.
Main Results:
- 85 out of 115 fair attendees became ill (73.9% attack rate).
- Salmonella Enteritidis PT 21 was identified in 20 patient stool specimens.
- Mixed salad containing potatoes was identified as the likely source (RR: 10.4).
- The outbreak strain was isolated from eggs, flock samples, and human cases, showing indistinguishable genetic profiles.
Conclusions:
- Cross-contamination between raw eggs and boiled potatoes in the kitchen likely caused the outbreak.
- Improper storage of peeled potatoes may have facilitated bacterial growth.
- Eggs from small, traditionally kept flocks are not necessarily Salmonella-free and pose a food safety risk.
Keywords:
salmonella
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