Denudation (medicine)

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In medicine, denudation refers to the loss of surface layers, such as the epithelium. Denudation coupled with peeling and cracking of skin gives rise to a "crazy pavement dermatosis" pattern seen in Kwashiorkor or Kwashiorkor-Marasmus complex.

In occupational asthma, the denudation of the bronchial mucosa can occur in the setting of nonimmunologic exposures (i.e., chemical spill, chlorine, ammonia), causing irritation.

Clostridioides difficile is known to cause formation of pseudomembranes in the intestines that is formed by denuded epithelium, neutrophilic infiltrate, fibrin, and bacteria due to the effects of its toxins: Toxin A (TcdA) and Toxin B (TcdB), which disrupt cellular cytoskeletons and tight junctions leading to cell death. [1]

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<span class="mw-page-title-main">Kwashiorkor</span> Severe protein malnutrition

Kwashiorkor is a form of severe protein malnutrition characterized by edema and an enlarged liver with fatty infiltrates. It is thought to be caused by sufficient calorie intake, but with insufficient protein consumption, which distinguishes it from marasmus. Recent studies have found that a lack of antioxidant micronutrients such as β-carotene, lycopene, other carotenoids, and vitamin C as well as the presence of aflatoxins may play a role in the development of the disease. However, the exact cause of kwashiorkor is still unknown. Inadequate food supply is correlated with occurrences of kwashiorkor; occurrences in high income countries are rare. It occurs amongst weaning children to ages of about five years old.

<i>Clostridioides difficile</i> infection Disease caused by C. difficile bacteria

Clostridioides difficile infection , also known as Clostridium difficile infection, is a symptomatic infection due to the spore-forming bacterium Clostridioides difficile. Symptoms include watery diarrhea, fever, nausea, and abdominal pain. It makes up about 20% of cases of antibiotic-associated diarrhea. Antibiotics can contribute to detrimental changes in gut microbiota; specifically, they decrease short-chain fatty acid absorption which results in osmotic, or watery, diarrhea. Complications may include pseudomembranous colitis, toxic megacolon, perforation of the colon, and sepsis.

<span class="mw-page-title-main">Colitis</span> Inflammation of the colon (large intestine)

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<span class="mw-page-title-main">Clostridia</span> Class of bacteria

The Clostridia are a highly polyphyletic class of Bacillota, including Clostridium and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them. Species of the class Clostridia are often but not always Gram-positive and have the ability to form spores. Studies show they are not a monophyletic group, and their relationships are not entirely certain. Currently, most are placed in a single order called Clostridiales, but this is not a natural group and is likely to be redefined in the future.

<span class="mw-page-title-main">Rifaximin</span> Antibiotic medication

Rifaximin, is a non-absorbable, broad spectrum antibiotic mainly used to treat travelers' diarrhea. It is based on the rifamycin antibiotics family. Since its approval in Italy in 1987, it has been licensed in over more than 30 countries for the treatment of a variety of gastrointestinal diseases like irritable bowel syndrome, and hepatic encephalopathy. It acts by inhibiting RNA synthesis in susceptible bacteria by binding to the RNA polymerase enzyme. This binding blocks translocation, which stops transcription. It is marketed under the brand name Xifaxan by Salix Pharmaceuticals.

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Streptolysins are two hemolytic exotoxins from Streptococcus pyogenes. Types include streptolysin O, which is oxygen-labile, and streptolysin S, which is oxygen-stable.

<span class="mw-page-title-main">Clostridium difficile toxin B</span>

Clostridium difficile toxin B is a cytotoxin produced by the bacteria Clostridioides difficile, formerly known as Clostridium difficile. It is one of two major kinds of toxins produced by C. difficile, the other being a related enterotoxin. Both are very potent and lethal.

<span class="mw-page-title-main">Clostridium difficile toxin A</span>

Clostridium difficile toxin A (TcdA) is a toxin generated by Clostridioides difficile, formerly known as Clostridium difficile. It is similar to Clostridium difficile Toxin B. The toxins are the main virulence factors produced by the gram positive, anaerobic, Clostridioides difficile bacteria. The toxins function by damaging the intestinal mucosa and cause the symptoms of C. difficile infection, including pseudomembranous colitis.

<span class="mw-page-title-main">AB toxin</span>

The AB toxins are two-component protein complexes secreted by a number of pathogenic bacteria, though there is a pore-forming AB toxin found in the eggs of a snail. They can be classified as Type III toxins because they interfere with internal cell function. They are named AB toxins due to their components: the "A" component is usually the "active" portion, and the "B" component is usually the "binding" portion. The "A" subunit possesses enzyme activity, and is transferred to the host cell following a conformational change in the membrane-bound transport "B" subunit. These proteins consist of two independent polypeptides, which correspond to the A/B subunit moieties. The enzyme component (A) enters the cell through endosomes produced by the oligomeric binding/translocation protein (B), and prevents actin polymerisation through ADP-ribosylation of monomeric G-actin.

Clostridium novyi (oedematiens) a Gram-positive, endospore- forming, obligate anaerobic bacteria of the class Clostridia. It is ubiquitous, being found in the soil and faeces. It is pathogenic, causing a wide variety of diseases in man and animals.

Colitis X, equine colitis X or peracute toxemic colitis is a catchall term for various fatal forms of acute or peracute colitis found in horses, but particularly a fulminant colitis where clinical signs include sudden onset of severe diarrhea, abdominal pain, shock, and dehydration. Death is common, with 90–100% mortality, usually in less than 24 hours. The causative factor may be Clostridium difficile, but it also may be caused by other intestinal pathogens. Horses under stress appear to be more susceptible to developing colitis X, and like the condition pseudomembranous colitis in humans, an association with prior antibiotic use also exists. Immediate and aggressive treatment can sometimes save the horse, but even in such cases, 75% mortality is considered a best-case scenario.

Shigatoxigenic Escherichia coli (STEC) and verotoxigenic E. coli (VTEC) are strains of the bacterium Escherichia coli that produce Shiga toxin. Only a minority of the strains cause illness in humans. The ones that do are collectively known as enterohemorrhagic E. coli (EHEC) and are major causes of foodborne illness. When infecting the large intestine of humans, they often cause gastroenteritis, enterocolitis, and bloody diarrhea and sometimes cause a severe complication called hemolytic-uremic syndrome (HUS). Cattle is an important natural reservoir for EHEC because the colonised adult ruminants are asymptomatic. This is because they lack vascular expression of the target receptor for Shiga toxins. The group and its subgroups are known by various names. They are distinguished from other strains of intestinal pathogenic E. coli including enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAEC), and diffusely adherent E. coli (DAEC).

Bezlotoxumab, sold under the brand name Zinplava, is a human monoclonal antibody designed for the prevention of recurrence of Clostridioides difficile infections.

<i>Clostridioides difficile</i> Species of bacteria

Clostridioides difficile is a bacterium that is well known for causing serious diarrheal infections, and may also cause colon cancer. It is known also as C. difficile, or C. diff, and is a Gram-positive species of spore-forming bacteria. Clostridioides spp. are anaerobic, motile bacteria, ubiquitous in nature and especially prevalent in soil. Its vegetative cells are rod-shaped, pleomorphic, and occur in pairs or short chains. Under the microscope, they appear as long, irregular cells with a bulge at their terminal ends. Under Gram staining, C. difficile cells are Gram-positive and show optimum growth on blood agar at human body temperatures in the absence of oxygen. C. difficile is catalase- and superoxide dismutase-negative, and produces up to three types of toxins: enterotoxin A, cytotoxin B and Clostridioides difficile transferase (CDT). Under stress conditions, the bacteria produce spores that are able to tolerate extreme conditions that the active bacteria cannot tolerate.

The Clostridial Cytotoxin (CCT) Family is a member of the RTX-toxin superfamily. There are currently 13 classified members belonging to the CCT family. A representative list of these proteins is available in the Transporter Classification Database. Homologues are found in a variety of Gram-positive and Gram-negative bacteria.

The Clostridium difficile TcdE Holin Family is a group of transporters belonging to the Holin Superfamily IV. A representative list of its members can be found in the Transporter Classification Database.

References

  1. Di Bella S, Ascenzi P, Siarakas S, Petrosillo N, di Masi A (May 2016). "Clostridium difficile Toxins A and B: Insights into Pathogenic Properties and Extraintestinal Effects". Toxins. 8 (5): 134. doi: 10.3390/toxins8050134 . PMC   4885049 . PMID   27153087.