Project description:<p>Traveler's diarrhea (TD) is caused by enterotoxigenic Escherichia coli (ETEC), other pathogenic gram-negative pathogens, norovirus and some parasites. Nevertheless, standard diagnostic methods fail to identify pathogens in more than 30% of TD patients, so it is predicted that new pathogens or groups of pathogens may be causative agents of disease. A comprehensive metagenomic study of the fecal microbiomes from 23 TD patients and seven healthy travelers was performed, all of which tested negative for the known etiologic agents of TD in standard tests. Metagenomic reads were assembled and the resulting contigs were subjected to semi-manual binning to assemble independent genomes from metagenomic pools. Taxonomic and functional annotations were conducted to assist identification of putative pathogens. We extracted 560 draft genomes, 320 of which were complete enough to be enough characterized as cellular genomes and 160 of which were bacteriophage genomes. We made predictions of the etiology of disease in individual subjects based on the properties and features of the recovered cellular genomes. Three subtypes of samples were observed. First were four patients with low diversity metagenomes that were predominated by one or more pathogenic E. coli strains. Annotation allowed prediction of pathogenic type in most cases. Second, five patients were co-infected with E. coli and other members of the Enterobacteriaceae, including antibiotic resistant Enterobacter, Klebsiella, and Citrobacter. Finally, several samples contained genomes that represented dark matter. In one of these samples we identified a TM7 genome that phylogenetically clustered with a strain isolated from wastewater and carries genes encoding potential virulence factors. We also observed a very high proportion of bacteriophage reads in some samples. The relative abundance of phage was significantly higher in healthy travelers when compared to TD patients. Our results highlight that assembly-based analysis revealed that diarrhea is often polymicrobial and includes members of the Enterobacteriaceae not normally associated with TD and have implicated a new member of the TM7 phylum as a potential player in diarrheal disease. </p>
| phs001352 | dbGaP
Project description:Genome sequencing and assembly of Gram-negative bacterial pathogens associated with nosocomial infections
Project description:To explore the circulating miRNA expression after subcutaneous injection of Gram negative and positive bacteria in the mice The recombinant specific Gram negative pathogens Escherichia coli (xen14) and Gram positive pathogens Staphyllococcus aureus (xen29) were purchased from the Caliper (Caliper, Princeton, NJ, USA). 1M-CM-^W108 Escherichia coli or Staphyllococcus aureus pathogen in 100 M-NM-<l PBS was injected subcutaneously with Fr. 25 needle into the back of the mice to cause bacterial infection of the mice. An extra group of animals was inoculated with PBS to serve as a negative control. The mice had access to food and water ad libitum both before and after bacteria injection. The mice were killed at the indicated time points (4, 8, and 24 h) after the bacteria injection, and whole blood was drawn.