Chocolate bars contaminated with Salmonella napoli: An infectivity study

Abstract

As a consequence of publicity a box of Rocky Junior milk chocolate bars was surrendered voluntarily by a market stallholder. The retailer was also the source of Rocky Junior bars which had been eaten by two local patients suffering from S napoli infection. S napoli was isolated from some of the bars. Preliminary investigations suggested that the number of salmonellae present in each chocolate bar was very small. As chocolate is a microbiologically stable product we decided to attempt to establish the probable infective dose by examining individual chocolate bars for S napoli. The results indicate a average of 1.6 S napoli organisms per gram. The mean weight of the individual bars was 16.6 g (range 12.3-18.4 g). Of the 42 bars containing salmonellae, 28 contained fewer than 10 S napoli and 12 contained 10-40 S napoli. S napoli was isolated from 42 of the 48 Rocky Junior chocolate bars examined.