These finding are in agreement with previous reports that showed that genetically closely related S. Enteritidis strains nevertheless presented important metabolic

differences, and that these differences were related to the accumulation of single this website nucleotide Ilomastat polymorphism rather than with differences in gene content [24]. Of note, none of the genes predicted as variant among S. Enteritidis in our work correspond to those described as involved in the ability to survive in the avian reproductive tract [50] or in persistence in egg albumen [51]. Furthermore, the genetic regions related to metabolic functions found as variable in our CGH analysis do not correspond to utilization of the compounds described by Morales et al. in their comparative phenotypic analysis of S. Enteritidis strains [24].

A report has recently been published showing differences in genetic content among S. Enteritidis isolates from prevalent phage types and the non-prevalent phage type 11 [26]. With the exception of the plasmid-encoded genes, all other genes reported as exclusively present Belnacasan cell line in the prevalent phage types, are also present in all the isolates analyzed here. Overall, our study shows that the epidemic of S. Enteritidis in Uruguay between 1995 and 2004 was caused by highly related S. Enteritidis isolates, perhaps comprising a PT4-like clonal population with few whole gene differences. To understand more clearly the link between genotype and phenotype and to differentiate between neutral variation within a population and variations associated directly with defined phenotypes, the whole genome sequences of a large number of isolates are required for association studies. This is our future see more direction. Methods Bacterial isolates A sample set of 266 isolates of S. Enteritidis isolated in Uruguay was defined among strains received at the National Salmonella Centre (Instituto de Higiene, Universidad de la República, Uruguay). Most (218) were isolated during the 9 years from 1995 to 2003 during

which there was a nationwide epidemic of food poisoning caused by S. Enteritidis. These included a selection of 112 isolates from human cases of gastroenteritis (around 15% of all isolates from faecal culture during the epidemic), all recorded isolates from human systemic infection (48 strains) and all isolates from non-human origin (58 strains). The sample set was completed with all isolates available (6 strains) from prior to the beginning of the epidemic, and 42 isolated after the epidemic declined. The description and source of all Uruguayan strains included in this study are shown in Tables 1 and 2. A UK isolate that had been completely sequenced and annotated (S. Enteritidis PT4 P12519, NCTC 13349) was used as the reference in all analyses [27]. S. Enteritidis PT4 P125109 is a human food-poisoning isolate which is highly virulent in newly-hatched chickens. Six S. Enteritidis isolates from other countries were included in CGH analysis.