Cronobacter (former Enterobacter sakazakii) spp.: its effect in dairy product safety, quality and trade

Cronobacter spp. (Enterobacter sakazakii) is a recently described genus that is made up of six species. These bacteria are opportunistic pathogens and are linked with life-threatening infections in neonates. Clinical symptoms of Cronobacter infection include necrotising enterocolitis, bacteremia, and meningitis, with case fatality rates of up to 80% being reported. Cronobacter are regarded as ubiquitous organisms having been isolated from a variety of environments, as well as foods, but so far only contaminated powdered infant formula has been epidemiologcally linked with infections. Recently, infections among immunocompromised adults, mainly elderly, have also been reported. Several features exhibited by these organisms, such as a high tolerance to osmotic and dry stress, as well as the ability to form capsules and biofilms containing exopolysacharides possibly conferring protection against environmental stresses may contribute to survival of Cronobacter spp, in the processing environment as well as in the products. Two possible routes have been described by which the organisms may be disseminated into the production lines/products: • organisms attached to soil/dust entering the product at a point after drying (e.g. filling stage); and • the use of dry ingredients that are added to the product without an additional heating step. Controlling the organisms in the production environment, thereby reducing dissemination, necessitates the existance of reliable diagnostic tools. Advances in cultural/molecular detection and subtyping techniques have significantly improved the identification and characterisation of Cronobacter spp. Continuous research (e.g. on the whole genome level) will help to gain a deeper insight into this opportunistic pathogen.