Bacteriological safety of cook-chill food at the Royal Free Hospital, with particular reference to Listeria

Abstract

Cook-chill food prepared by the Catering Department of the Royal Free Hospital was examined over an 8-month period commencing October 1989. Total aerobic viable counts (TAVCs) were performed on 200 food specimens which were also examined for Listeria using selective enrichment culture. Ten of 200 food samples tested had TAVCs > 10 5 colony forming units (cfu) g −1, and nine of these were from non-vegetarian (meat) dishes. Although most of the food prepared by cook-chill had microbial loads within the limits recommended by current Department of Health guidelines (i.e. <10 5 cfu g −1), our findings for the non-vegetarian dishes suggest that extra caution is required when preparing such food. Listeria were not isolated from any food sample. In a survey of listeria faecal carriage, Listeria monocytogenes was isolated from only two of 100 faeces specimens obtained from patients.