Chapter 17: Culture Media for Isolating Cronobacter species (Enterobacter sakazakii) Check Access

Cronobacter is a newly proposed genus containing five species and is contaxic with Enterobacter sakazakii. These organisms persist in dry environments, including powdered foods. There is concern about their presence in powdered infant formula, following links between neonatal infections and contaminated formula. Methods for the isolation and detection of Cronobacter have been complicated by the sensitivity of a number of strains to selective agents commonly used in media for Enterobacteriaceae, such as bile salts, dyes and antibiotics. Differentiation of Cronobacter colonies from those of non-target organisms can be achieved using a combination of sucrose fermentation, ornithine decarboxylation and hydrolysis of chromogenic α-D-glucosidase substrates. Development of a horizontal EN ISO standard is currently ongoing and validation of proposed detection methods is being undertaken by AOAC International.