Contamination and persistence of pathogenic microorganisms on food can lead to outbreaks of foodborne illness. Investigating the food source that caused the illness, identifying how the pathogen entered the food production environment, and how the pathogen survived in the food product are important for preventing future outbreaks. Here we define foodborne illness outbreaks, traceback investigations, and apply basic microbial growth principles to a foodborne outbreak of salmonellosis linked to peanut butter.

Salmonella contamination in dry and low-moisture food processing environments is a food safety concern recognized by the FDA. For a microorganism to grow in a food processing environment, there must be enough available moisture for the organism to use. In a dry or low-moisture processing environment, there are typically not enough consistent sources of moisture for microorganisms to grow; however, Salmonella has shown the ability to adapt to this low-moisture stress and survive for long periods of time through accumulation of osmoprotectants, up-regulation of outer membrane porins, alteration of gene expression, rRNA degradation, entering a viable but not culturable state, filamentation, and biofilm formation.