Salmonella Enteritidis phage type 21 outbreak in Austria, 2005

Abstract

We report an outbreak of gastroenteritis due to Salmonella Enteritidis PT 21 associated with attending an annual traditional fair in a small Austrian village on 4 May 2005. The outbreak lasted from 4 to 8 May. Descriptive and analytical epidemiological investigations were conducted in order to determine the extent of the outbreak and to identify outbreak risk factors. Of the 115 persons who visited the fair, 85 persons fulfilled the criteria of an outbreak case (attack rate=73.9%). Stool specimens from 52 patients, including two kitchen staff, were tested for salmonella, and 20 specimens were positive for Salmonella Enteritidis PT 21. The cohort study revealed mixed salad (which included potatoes) as the likely cause of the outbreak (RR: 10.4, 95%CI 2.8 - 39.1; P=<0.001). The causative agent of the outbreak was cultured from the stock of eggs used at the fair and from all three drag swabs and one barn dust sample collected from the responsible egg laying flock. Molecular subtyping by pulsed-field gel electrophoresis of genomic DNA after XbaI digestion showed that isolates from eggs, from the flock and from humans were indistinguishable. We hypothesise that cross contamination from eggs to boiled potatoes occurred in the kitchen area, where raw eggs were handled by village residents preparing a traditional Viennese egg dressing. Unrefrigerated storage of peeled potatoes may have favoured bacterial growth. Eggs from small rural flocks of laying hens kept in a traditional 'natural' way should not be assumed to be salmonella-free.

Molecular characterization and resistance profile of Salmonella Enteritidis PT4 and PT9 strains isolated in Brazil

“…1a, b). Similar to the results in the present study, other investigators in Austria (Schmid et al, 2006), Chile (Fernandez et al, 2003), Korea (Woo, 2005) and Senegal (Cardinale et al, 2005) have found high similarity between PFGE patterns of S. Enteritidis strains isolated from poultry products and from patients with salmonellosis.…”

Multiple-locus variable-number tandem repeat analysis for subtyping of Salmonella enterica subsp. enterica serovar Enteritidis

“…The current 'gold standard' in subtyping of S. Enteritidis is macrorestriction with restriction endonucleases followed by pulsed-field gel electrophoresis (PFGE) separation of the large DNA fragments (Gatto et al, 2006). PFGE has proven to be useful and reliable in outbreak investigations due to its good discriminatory power (Lukinmaa et al, 1999;Schmid et al, 2006). However, the method is plagued by some significant pitfalls, mainly the complex and time-consuming procedure and reduced comparability of results between different laboratories.…”

Salmonellosis in Austria: situation and trends

“…In the course of an outbreak the NRCS is able to support the outbreak investigation team with additional information by using molecular discrimination techniques such as PFGE or MLVA. Based on the close cooperation of public health authorities, veterinary disease control officers, and food inspectors with the Competence Center for Infectious Diseases Epidemiology and the NRCS several outbreaks have been traced back to their sources thereby preventing further infections [24][25][26][27][28]. These measures -the introduction of the vaccination of laying hens and broilers and intensified outbreak investigation efforts -have led to a remarkable decrease of human salmonella infections in Austria.…”