Therefore we designated the cluster with the largest number of ST 4 strains as pathogenic. Since it is reasonable to check details assume that similar MLST types will have similar levels of pathogenicity, the spectrum of MLST types in each cluster is a good indicator of
the accuracy of the assignment, and takes into account factors such as differences between species of Cronobacter. To date only a few plausible virulence features have been identified, such as ompA, adhesins, and iron-uptake mechanisms, many of which are distributed across the seven Cronobacter species . Consensus clustering Consensus clustering was carried out to combine the results generated by the four tests. It was hypothesised that the consensus clustering will result in a more accurate classification of strains in the appropriate cluster. The four clustering assignments were combined by way of each assignment having one vote with the
majority determining the cluster assignment of each strain. Any tie (i.e. two of four votes for each cluster) in the voting resulted in the strain being placed in the pathogenic cluster; this decreased the probability of missing a pathogenic strain while increasing the risk of finding a false positive. However, this was accepted as a good compromise, since missing a pathogenic strain has more serious consequences than misidentifying a negative strain. The consensus clustering was carried out on the 48 strains for which data for all four diagnostic tests is available. Acknowledgements The authors thank Nottingham Trent University for the funding of this project. Electronic CP-690550 supplementary material Additional File 1: Cronobacter strains. Strains used in this study including source of isolation, MLST Type, references and which experiments they were used in. (XLS 48 KB) References 1. Farmer JJ, Asbury MA, Hickman FW, Brenner DJ, The Enterobacteriaceae study group: Enterobacter sakazakii : a new species Sinomenine of “” Enterobacteriaceae “” isolated from clinical specimens. Intl J System Bacteriol
1980, 30:569–584.CrossRef 2. Iversen C, Mullane N, McCardell B, Tall B, Lehner A, Fanning S, Stephan R, Joosten H: Cronobacter gen. nov., a new genus to accommodate the biogroups of Enterobacter sakazakii , and proposal of Cronobacter sakazakii gen. nov., comb. nov., Cronobacter malonaticus sp. nov., Cronobacter turicensis sp. nov., Cronobacter muytjensii sp. nov., Cronobacter dublinensis sp. nov., Cronobacter genomospecies 1, and of three subspecies, Cronobacter dublinensis subsp. dublinensis subsp. nov., Cronobacter dublinensis subsp. lausannensis subsp. nov. and Cronobacter dublinensis subsp. lactaridi subsp. nov. Intl J System Evol Microbiol 2008, 58:1442–1447.CrossRef 3. Joseph S, LY2835219 Cetinkaya E, Drahovska H, Levican A, Figueras M, Forsythe SJ: Cronobacter condimenti sp. nov.