Comparison of phenotypic and genotypic characteristics of Salmonella bredeney associated with a poultry-related outbreak of gastroenteritis in Northern Ireland

Abstract

Objectives: To employ a combination of phenotypic and genotypic subspecies typing methods to aid in an epidemiological investigation of an outbreak of Salmonella bredeney involving ten persons.

Methods: Isolates were characterised by employing antibiogram typing, in addition to two genotyping techniques, including pulsed field gel electrophoresis (PFGE), random amplification of polymorphic DNA (RAPD) with two oligonucleotide primers.

Results: An outbreak of gastroenteritis associated with S. bredeney (serovar O:4 H:Lv 1,7) occurred in Belfast, Northern Ireland in November 1997. In total, ten cases were confirmed, of which eight had consumed chicken cooked at local butchers and retailed through one of two local bakeries. One of the remaining cases was secondarily infected within her home and the final case had eaten a product other than cooked chicken from one of the bakeries. Food preparation practices were inadequate in one of the bakeries in question and record keeping and possibly cooking procedures were inadequate in the butchers. S. bredeney was isolated from an uncooked chicken supplied to the butchers confirming that improperly cooked chicken was most likely the source of the outbreak. All outbreak clinical isolates were indistinguishable from each other and were similar to the isolate obtained from the uncooked poultry demonstrating that these DNA-based methods were valuable in the molecular characterization of S. bredeney.

Conclusions: This report emphasises the importance and maintenance of an effective hazard analysis critical control point (HACCP) approach to the processing and retailing of foodstuffs containing chicken in order to help eliminate hazards to public health.