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_007168:2631535 Staphylococcus haemolyticus JCSC1435, complete genome

Lineage: Staphylococcus haemolyticus; Staphylococcus; Staphylococcaceae; Bacillales; Firmicutes; Bacteria

General Information: Staphylococcus haemolyticus JCSC1435 was isolated from a Japanese inpatient at Juntendo Hospital, Tokyo, in 2000. This strain is a highly resistant strain which has been shown to generate spontaneous antibiotic sensitive mutants. Causes opportunistic infections in humans. Staphylcocci are generally found inhabiting the skin and mucous membranes of mammals and birds. Some members of this genus can be found as human commensals and these are generally believed to have the greatest pathogenic potential in opportunistic infections. Staphylococcus haemolyticus was originally isolated from human skin and traditionally considered to be a nonpathogenic commensal. Recently this organism has been recognized as a pathogen in animals and humans. It is known to be involved in opportunistic infections associated with the implantation of foreign bodies, paticularly in those with compromised immune systems. Resistance to multiple antibiotics has been observed in clinical isolates and it is possible S. haemolyticus could serve a donor or resistance genes to other more virulent staphlococci.