Query: NC_016809:389561 Haemophilus influenzae 10810, complete genome
Lineage: Haemophilus influenzae; Haemophilus; Pasteurellaceae; Pasteurellales; Proteobacteria; Bacteria
General Information: A group of organisms that are either obligate parasites or commensal organisms found in animal mucous membranes. Almost all species require the presence of important growth factors found in the blood of their hosts, including either X factor (protoporphyrin IX or heme) or V factor (nicotinamide adenine dinucleotide (NAD or NADP)). This organism was first isolated in the 1890s during an influenza pandemic by Pfeiffer, and was originally thought to be the source of influenza, although later it was shown to be a secondary pathogen and may be synergistic with the influenza virus. This bacterium is one of the leading causes of meningitis in young children, and it may also cause septicemia, otitis media (inflammation of the middle ear), sinusitis (inflammation of the sinus cavity) and chronic bronchitis. It is highly adapted to its human host and typically lives in the nasopharynx and is a major cause of lower respiratory infections in infants and small children in developing countries (type 1b strain), although vaccine use has resulted in the decline of infections. The encapsulated organism can penetrate the blood and avoid both phagocytosis and complement-mediated lysis. All known strains produce neuraminidase and an IgA protease as well as fimbrial adhesins for attachment.
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.