Query: NC_004917:946550 Helicobacter hepaticus ATCC 51449, complete genome
Lineage: Helicobacter hepaticus; Helicobacter; Helicobacteraceae; Campylobacterales; Proteobacteria; Bacteria
General Information: This organism was found to be linked to an increasing incidence of liver tumors in mouse colonies at the National Cancer Institute in 1992. Normally it resides in the lower intestines, but it can cause chronic hepatitis. This organism has a similar urease gene cluster and cytolethal distending toxin as compared to Helicobacter pylori, but lacks other virulence factors such as the vacuolating cytotoxin and the cag pathogenicity island. However, it does contain a pathogenicity island that encodes proteins similar to those found in a type IV secretion system. Causes liver disease. This genus consists of organisms that colonize the mucosal layer of the gastrointestinal tract or are found enterohepatically (in the liver). This species was associated with an increase in liver tumors. It can cause active chronic hepatitis and typhlitis (inflammation of a region at the beginning of the large intestine), hepatocellular tumors, and gastric bowel disease in various mice strains.
Subject: NC_009089:1 Clostridium difficile 630, complete genome
Lineage: Peptoclostridium difficile; Peptoclostridium; Peptostreptococcaceae; Clostridiales; Firmicutes; Bacteria
General Information: This strain is the epidemic type X variant that has been extensively studied in research and clinical laboratories. It produces both toxin A, and B. Causative agent of pseudomembranous colitis. This genus comprises about 150 metabolically diverse species of anaerobes that are ubiquitous in virtually all anoxic habitats where organic compounds are present, including soils, aquatic sediments and the intestinal tracts of animals and humans. This shape is attributed to the presence of endospores that develop under conditions unfavorable for vegetative growth and distend single cells terminally or sub-terminally. Spores germinate under conditions favorable for vegetative growth, such as anaerobiosis and presence of organic substrates. It is believed that present day Mollicutes (Eubacteria) have evolved regressively (i.e., by genome reduction) from gram-positive clostridia-like ancestors with a low GC content in DNA. Some species are capable of producing organic solvents (acetone, ethanol, etc,), molecular hydrogen and other useful compounds. This species is now recognized as the major causative agent of pseudomembranous colitis (inflammation of the colon) and diarrhea that may occur following antibiotic treatment. This bacterium causes a wide spectrum of disease, ranging from mild, self-limiting diarrhea to serious diarrhea and, in some cases, complications such as pseudomembrane formation, toxic megacolon (dilation of the colon) and peritonitis, which often lead to lethality among patients. The bacteria produce high molecular mass polypeptide cytotoxins, A and B. Some strains produce only one of the toxins, others produce both. Toxin A causes inflammatory reaction involving hypersecretion of fluid and hemorrhagic necrosis through triggering cytokine release by neutrophils. Alteration of intestinal microbial balance with antibiotic therapy and increased exposure to the bacterium in a hospital setting allows C. difficile to colonize susceptible individuals. Moreover, it has been shown that subinhibitory concentrations of antibiotics promote increased toxin production by C. difficile.