Pre_GI: SWBIT SVG BLASTP

Query: NC_017179:2895571 Clostridium difficile BI1, complete genome

Lineage: Peptoclostridium difficile; Peptoclostridium; Peptostreptococcaceae; Clostridiales; Firmicutes; Bacteria

General Information: Clostridium difficile BI1 is a human strain isolated in the United States in 1988. 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. C. difficile infection represents one of the most common nosocomial (originating in a hospital) infections. 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. Cytotoxin B depolymerizes actin, the major protein of the cytoskeleton, and thus aids in destruction of tissues. The combined action of the toxins results in necrosis of superficial epithelium and edema (fluidic swelling) in affected areas of intestine. Proliferation of C. difficile is normally prevented by normal intestinal microflora, which is believed to inhibit attachment of the bacterium and its toxins to intestinal walls. 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.

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Subject: NC_004722:5381208 Bacillus cereus ATCC 14579, complete genome

Lineage: Bacillus cereus; Bacillus; Bacillaceae; Bacillales; Firmicutes; Bacteria

General Information: Soil microorganism that can cause food poisoning. This organism is a soil-dwelling opportunistic pathogen that causes food poisoning in infected individuals. There are two forms of food poisoning that occur, one is rapid onset (emetic) and the other is late onset (diarrheal). The rapid onset is characterized by nausea and vomiting while the late onset is characterized by diarrhea and abdominal pain. The emetic disease is caused by a small stable dodecadepsipeptide cerulide whereas the diarrheal disease is caused by a heat labile enterotoxin. Some strains produce a potent cytotoxin that forms a pore in the membrane of eukaryotic cells and causes necrotic enteritis (death of intestinal epithelial cells) while the unique tripartite membrane lytic toxin hemolysin BL contributes to the diarrheal disease and destructive infections of the eye.