Person with necrotizing fasciitis. The left leg shows extensive redness and necrosis. Necrotizing fasciitis ˈnɛkrəˌtaɪzɪŋ ˌfæʃiˈaɪtɪs/ or /ˌfæs- or NF, commonly known as flesh-eating disease, flesh-eating bacteria or flesh-eating bacteria syndrome,[1] is a rare infection of the deeper layers of skin and subcutaneous tissues, easily spreading across the fascial plane within the subcutaneous tissue. The most consistent feature of Necrotizing Fasciitis was first described in 1952 as necrosis of the subcutaneous tissue and fascia with relative sparing of the underlying muscle.[2] Necrotizing fasciitis progresses rapidly, having greater risk of developing in the immunocompromised due to conditions such as diabetes or cancer. It is a severe disease of sudden onset and is usually treated immediately with surgical debridement and high doses of intravenous antibiotics,[3] with delay in surgical treatment being associated with higher mortality. Many types of bacteria can cause necrotizing fasciitis (e.g., Group A streptococcus ( Streptococcus pyogenes Staphylococcus aureus, Clostridium perfringens, Bacteroides fragilis, Aeromonas hydrophila[4]). The disease is classified as Type I (polymicrobial, due to a number of different organisms) or Type II (monomicrobial, due to a single infecting organism). The majority of cases of necrotizing fasciitis are polymicrobial, with 25-45% of cases being Type II.[5] Such infections are more likely to occur in people with compromised immune systems secondary to chronic disease.[6] Historically, most cases of Type II infections have been due to group A streptococcus and staphylococcal species. Since as early as 2001, a particularly difficult to treat form of monomicrobial necrotizing fasciitis has been observed with increasing frequency[7] caused by methicillin-resistant Staphylococcus aureus ( MRSA). Contents 1 Possible sources 2 Signs.
Nylon-eating bacteria are a strain of Flavobacterium that is capable of digesting certain byproducts of nylon 6 manufacture. This strain of Flavobacterium, Sp. KI72, became popularly known as nylon-eating bacteria, and the enzymes used to digest the man-made molecules became collectively known[clarification needed ( Popularly or scientifically?)] as nylonase. Contents 1 Discovery 2 Later research 3 Role in evolution teaching 4 See also 5 Notes 6 References Discovery[edit] Chemical structure of 6-aminohexanoic acid In 1975 a team of Japanese scientists discovered a strain of Flavobacterium, living in ponds containing waste water from a nylon factory, that was capable of digesting certain byproducts of nylon 6 manufacture, such as the linear dimer of 6-aminohexanoate. These substances are not known to have existed before the invention of nylon in 1935. Further study[clarification needed ( In the same paper, as implied by the position of the reference note?)] revealed that the three enzymes the bacteria were using to digest the byproducts were significantly different from any other enzymes produced by other Flavobacterium strains (or, for that matter, any other bacteria and not effective on any material other than the manmade nylon byproducts.[1] Later research[edit] This discovery led geneticist Susumu Ohno in a paper published in April 1984 to speculate that the gene for one of the enzymes, 6-aminohexanoic acid hydrolase, had come about from the combination of a gene duplication event with a frameshift mutation.[2] Ohno suggested that many unique new genes have evolved this way. A 2007 paper that described a series of studies by a team led by Seiji Negoro of the University of Hyogo, Japan, suggested that in fact no frameshift mutation was involved in the evolution of the 6-aminohexanoic acid hydrolase.[3] However, many other genes have been discovered which did evolve.
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