Survival of Brucella spp. in mineral water, milk and yogurt

Knowledge of the number of organisms in a food product at the time of consumption is crucial to assess the risk from a deliberate contamination of food samples with Brucella. To date, very little data on the survival times of Brucella in different food matrices is available. This study was conducted to assess the survival times of Brucella spp. in water, milk and yogurt. These food products were inoculated with bacteria, serial dilutions of the food samples plated and the number of surviving bacteria counted. Under normal storage conditions Brucella survived in UHT milk for 87 days, for 60 days in water and less than a week in yogurt. Also, when milk was inoculated with low bacterial numbers, Brucella multiplied by five log units within three weeks. Further we could not confirm that a high fat content in food has a protective effect on Brucella survival. Brucella survived in 3.5% and 10.0% fat yogurt for four and two days, respectively. These results show that appropriate methods for the rapid detection of this pathogen from food matrices are required.