Technical Abstract: Recent advances in nucleic acid microarray technology now make it possible to directly compare PT13a S. enteritidis in DNA-DNA hybridization assays to the complete genomes of Salmonella typhimurium LT2 and Salmonella enteritidis PT4 in order to detect how phage type correlates with genomic organization. These proceedings are a first report on bacteriophage content of S. enteritidis phage types 4 and 13a, which are representative members of the two main phage lineages of this important cause of food borne illness. Results were that phage specific to each of the lineages were identified. This research was made possible by collaboration between the Wellcome Trust Sanger Center, the Sidney Kimmel Cancer Institute and USDA.