Occurrence of Salmonella Enteritidis phage type 29 in Austria: an opportunity to assess the relevance of chicken meat as source of human Salmonella infections.

Assuming that the various phage types of Salmonella Enteritidis (S. Enteritidis) are largely equally virulent, the importance of certain foods as sources of infection for human salmonellosis can be deduced from differences in the distribution of phage types in human and non-human samples. In 2002, S. Enteritidis phage type 29 (PT29) was first isolated from non-human test samples in Austria. S. Enteritidis PT29 accounted for 44 (27.7%) of 159 S. Enteritidis strains, derived from veterinary samples of chicken (e.g. meat, giblets) or chicken habitations (e.g. swabs from the coop and excrement). At the food retail level (chicken meat, chicken liver), five (13.1%) of 38 S. Enteritidis isolates were PT29. The proportion of S. Enteritidis PT29 in human samples was much lower. Only 0.4% (30 human primary isolates) of all S. Enteritidis isolates in the year 2002, and 0.33% (23 human primary isolates) of all human S. Enteritidis strains in 2003 were PT29. In our opinion, the discrepancy between the high prevalence of S. Enteritidis PT29 in broilers and chicken meat and the low number of PT29 cases in humans indicates that chicken meat of Austrian origin is currently only a minor source of human S. Enteritidis infections.