MALDI-TOF MS identification of citrobacter youngae isolated from food

Salmonella-like bacteria, such as certain species of the Citrobacter genus are sometimes isolated from food and feed. By testing their biochemical and, partially, serological characteristics (according to the regulations given in the ISO 6579-1:2017 Standard) it is impossible to completely reject their affiliation to the Salmonella genus. In addition to this, the food microbiology laboratories usually lack diagnostic tools and procedures for precise identification of these isolates to the species level. Thus, it is considered useful to describe the identification of Citrobacter youngae species using MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry). Besides differential diagnostic criteria for distinguishing between Salmonella spp. and Citrobacter youngae, in this communication the relevant data on Citrobacter spp., the emerging opportunistic pathogenic member of Enterobacteriaceae family were presented.