Conclusions Here we have used Expectation Maximization clustering to divide strains of Cronobacter into groups of pathogenic and non-pathogenic strains based on the results of diagnostic biochemical tests. The clustering assignments showed

promise, clearly dividing the data into two clusters containing obviously pathogenic and non-pathogenic strains, based on the source of isolate and the MLST type of the strain. However, further experiments characterising the pathogenicity of Cronobacter strains are required to confirm the accuracy of the classification. Nevertheless, our results demonstrated a clear association between pathogenic strains and inositol fermentation, supported by genomic proximity of putative virulence factors to the gene coding for inositol monophosphatase. Methods Sources of bacterial strains A total of 98 BTSA1 research buy selleckchem Cronobacter strains were analyzed in this study. Strains were from diverse food, clinical and environmental sources worldwide. The following species of Cronobacter were included:

C. sakazakii NCTC 11467T, C. malonaticus LMG 23826T, C. turicensis LMG 23827T, C. muytjensii ATCC 51329T, C. dublinensis LMG 23823T, C. universalis NCTC 9529T. Strains were kindly donated by the following organizations: Health Products and Food Branch (Health Canada); CDC(Atlanta, USA); Children’s Hospital (Los Angeles CA, USA); Northern Foods (UK); Oxoid ThermoFisher Ltd. (Basingstoke,

UK); Hospital Cèské Budéjovice (Czech Republic); Institut fûr Tierärztliche Nahrungsmittelkunde Milchwissenschaften (Justus-Liebig-Universität Gießen, Germany); Nottingham City Hospital Trust (Nottingham, UK) and the Department of Medical Microbiology, aminophylline Radboud (Nijmegen, Netherlands). All other strains were food and environmental isolates from the culture collection at Nottingham Trent University (Nottingham, UK) [19]. Dataset We examined results from four sets of diagnostic tests carried out on a total of 98 strains encompassing six species of Cronobacter. For a complete list of strains used in this work and their details see Additional File 1 and references [[1–3, 15, 18] and [20–28]]. Each test comprises a series of enzyme assays which produce a colour change recorded by the user. Bacterial species can then be identified by a characteristic series of changes in colour. All tests were carried out in accordance with the manufacturers’ instructions and replicated three times; biotyping was performed as in [1]. The tests were those commonly used in the identification of Cronobacter species, and in taxonomic descriptions of the genus [2, 3, 12, 19]. The four tests were: Test 1 API 20 E (bioMérieux; SA, Marcy-l’Etoile, France) [29] consists of 20 enzyme assays scored as positive or negative.