1,721,721 research outputs found
Bacillus Calmette-Guerin
No full textApproximately one third of the world population is infected by Mycobacterium
tuberculosis, and a greater and continuing factor that is bolstering the ongoing
tuberculosis (TB) epidemic is the human immune deficiency virus (HIV). Further
complicating the issue, multidrug resistance (MDR) has arisen worldwide, and by
early 2010, 58 countries had reported at least one case of extensively drug resistant
TB . For all these reasons, TB prevention through vaccination is a key global
health priority.
Various vaccines have been shown to reduce the risk of disease and mortality
due to TB in man, but only one has been used in global immunization programs:
the M. bovis bacillus Calmette-Guérin (BCG). BCG is an attenuated live vaccine
administered at birth to children in most countries where TB is endemic. It is the
vaccine most widely used all over the world, and an estimated three billion doses
have been administered to date. Despite having reduced the burden of TB in
many zones, the BCG has various limitations and so the development of more efficacious
vaccines against TB is an extremely urgent issue. The ideal vaccine
should prevent both the initial tubercle infection and the development of active
disease, or reactivation in previously infected healthy hosts as well as in particularly
vulnerable populations (HIV-infected and other immunocompromised individuals)
Mycobacterium ulcerans infection
No full textMycobacterium ulcerans is the causative agent of a new emerging infectious disease,
which has been reported in at least 33 countries worldwide with tropical, subtropical
and temperate climates.
Classified by the WHO as one of the 17 neglected tropical diseases,
M. ulcerans infection is the third most common mycobacterial disease in the world,
after tuberculosis and leprosy. In East Africa, where it is endemic and thousands of
cases are observed annually, the infection is the second most important mycobacterial
disease after tuberculosis.
Buruli ulcer disease (the name adopted for this infection worldwide) is often
referred to as the “mysterious disease” because the mode of transmission remains
unclear, although several hypotheses have been proposed. It is a serious necrotizing
infection due to a toxin, mycolactone, produced by the bacilli, that necrotizes
the subcutaneous tissue leading to deep ulceration. This is the most severe
form of the disease. Early detection before ulceration is therefore the key to
prompt cure; otherwise, if diagnosed late, the infection may leave patients with
disabling sequelae, such as scarring contractures and possible bone destruction
requiring amputation
Mycobacterium scrofulaceum infection
No full textMycobacterium scrofulaceum is a member of the Runyon class II scotochromogen
acid-fast bacilli. It is widely present in nature, but is now an infrequent human
pathogen. It was first described in the 1950s and the name likely derives from
its isolation from cervical lymph nodes
Mycobacterium bovis skin infection
No full textThe bovine tubercle bacillus must firstly be placed in context among the other
agents of tuberculosis. In the early decades of the twentieth century, bacteriologists
recognized four varieties of tubercle bacilli (human, bovine, avian and
cold-blooded), depending on the life forms from which they were isolated. By the
middle of the century, only two varieties were still recognized as agents of human
and bovine tuberculosis (TB), namely Mycobacterium tuberculosis and M. bovis, respectively.
In the 1960s, another TB agent was isolated in Africa, and named M. africanum, but this was later seen to include two varieties. Finally, in the 1980s it was
found that two varieties of M. tuberculosis itself could also be distinguished: classical
and Asian. This group of organisms, to which M. microti, M. pinnipedii,
M. canettii, and M. caprae were later added, is denominated the M. tuberculosis
complex . The bacillus Calmette-Guérin (BCG) was classed with M.
bovis. The avian and cold-blooded tubercle bacilli were then classified separately:
the first, that includes M. avium and M. intracellulare, is included in the M.
avium complex (together with M. lepraemurium and M. paratuberculosis), while
the second includes M. chelonae and M. fortuitum
Dermatitis caused by algae and bryozoans
No full textAlgae and Bryozoans can cause various clinical pictures. Algae are found in all aquatic environments. Some species of Cyanophyceae (“blue-green algae”) and Dinophyceae classes, present in salt and freshwater, produce one or more toxins, some of which are strongly neurotoxic or hepatotoxic, while others provoke gastroenteritis and skin disorders. The skin toxicity can manifest in humans with irritant and allergic reactions. A particular alga of the Cyanophyceae, present in various localities of Australia, Florida and Hawaii, periodically induces the so-called swimmer’s itch, a dermatitis whose onset occurs a few minutes after bathing, with intense itching and burning sensations, followed after 3-8 h by blisters leaving painful erosions in the areas covered by the swimming costume. Skin protothecosis is another infection induced by seaweed, that mainly affects immunocompromised subjects, triggering various clinical pictures. The affliction, reported in various parts of the world, is difficult to diagnose. The lesions can persist for years and there is no known elective treatment. Bryozoans (moss), belonging to the animal kingdom, can cause quite a disabling contact dermatitis in fishermen, featuring dry, fissuring and exudative lesions of the hands and forearms. The complaint, that may also be of an allergic nature, can become generalized
Dermatitis caused by sponges
No full textIt has long been known that sponges, the most primitive pluricellular organisms, are not entirely innocuous. Some species can, in fact, cause serious skin reactions, induced by the spicules on the horny skeleton or by the toxins present on their surface or secreted into the water. Clinical manifestations due to stings of sponges may be immediate or delayed. A few minutes after the contact, prickling, stinging or burning occur, followed by pain, erythema, swelling and stiffness. The dermatitis progresses to papulo-vesicular or bullous eruptions with a serous or purulent exudate. The onset of the affliction may occur even many days after the contact. Some species of sponges can also provoke much more violent reactions, and unless they are adequately treated such complaints may persist for several months. Apart from the above-mentioned contact dermatitis from chemical agents, some sponges can induce traumatic dermatitis after contact with the spicules, which penetrate the skin and cause foreign-body reactions. The spicules of fresh water sponges float in suspension in the water and provoke a generalized erythematous papular eruption, that can result in possible blindness in some cases. It is important to bear in mind that subjects with early signs of a reaction immediately after the contact should be warned of the risk of delayed effects as well
Dermatitis caused by fish
No full textMany species of fish are venomous and poisonous to man. Venomous fish produce toxic substances that can be inoculated during stings or bites. Some fish with a cartilaginous skeleton (stingrays) live on sandy bottoms and most injuries occur when bathers, waders, or fishermen accidentally step on their bodies, when they will arch their tails and project the spine violently against the victim’s legs. Local pain is immediate and very severe: it is acute, throbbing or piercing and lasts 1-2 days. General symptoms, involving the cardiocirculatory, gastroenteric and muscle systems, can even be fatal. Weeverfish, that have spines on various parts of the body, are among the most dangerous venomous fishes. Accidental contact with these fish causes a very severe reaction that may be fatal due to cardiac arrest. Contact with the spines of scorpionfish, among the most numerous and geographically widespread toxic fishes, also causes anguishing pain and very serious systemic symptoms, that can again be fatal. The bites of moray eels, too, cause intense local pain and serious systemic signs; occasionally, when harpooned, the battle between the fisherman and a large animal can have fatal consequences. The possible shock due to contact with a fish with an electric apparatus is not generally strong enough to cause skin or nerve lesions, apart from a state of stupor that could be dangerous during emersion procedures. Passively toxic fish, that do not produce toxins but acquire them from the environment, are poisonous only when eaten and can cause various serious poisoning syndromes (ciguatera fish, tetrodotoxic and scombrotoxic poisonings)
Mycobacterium marinum skin infection
No full textMycobacterium marinum lives in aquatic environments, where it causes disease in
many poikilodermic fish species living in fresh or saltwater; the organism has a
wide geographic distribution in the water world. The first report of a mycobacterium
isolated in fish (very likely M. marinum) is attributed to Bataillon and Coll,
who isolated acid-fast bacilli, named M. piscium, in 1897, from a tuberculous
lesion of a common carp (Cyprinus carpio). Then in 1926 it was isolated and
identified by Aronson from tubercles in various organs of marine fish found dead
in the Philadelphia Aquarium. Initially M. marinum was thought to infect fishes
only and was named accordingly, but it is now known to be a ubiquitous species.
The original freshwater isolate of M. piscium was quite possibly a variant of
M. marinum. Other marine Mycobacterium species have been described in the literature,
such as M. platypoecilus, M. anabanti, and M. balnei; however, comparative
cultural, morphological, and pathogenic data suggest that they were all
synonymous with M. marinum.
M. marinum was identified as a causal agent of human disease only in 1951, when
it was identified from skin lesions in swimmers in a contaminated swimming pool in
the city of Orebro, Sweden. The term “swimming pool granuloma” was coined to
denote these lesions and the causal agent was classified as M. balnei but then,
when the two mycobacteria were later seen to be identical, as M. marinum
Dermatitis caused by coelenterates
No full textThe phylum of Coelenterata (Cnidaria), animals that have a worldwide distribution, includes four toxic classes: Anthozoa (sea anemones, true hard and soft corals and sea pens), Scyphozoa (true jellyfish), Hydrozoa (physalia and fire corals: not true corals), and Cubozoa (box jellyfish). Highly specialized cells (nematocytes) are present on the surface of Coelenterata, and associated with the venom discharged during stings. An organ synthesized by the nematocytes, the nematocyst, is expelled in a harpoon-like fashion during a nanosecond process, and injects different active toxic substances into the prey. Injuries caused by cnidarians are of two pathogenic orders, toxic (the most common mechanism) and allergic (of immediate or delayed type). Different clinical pictures can arise after Cnidarians envenomations, featuring skin and systemic reactions that can even be fatal. True jellyfish induce a great number of accidents in the world, although they are generally less severe than those caused by box jellyfish and physaliae. Box jellyfish are among the most significant toxic marine animals, and their envenomation usually presents as a medical emergency. Sea anemones can cause cutaneous and systemic manifestations, including seabather’s eruption, characterized by pruriginous papulous lesions that persist for 1-4 weeks. True corals provoke skin lesions through toxic and traumatic mechanisms. Physaliae stings are usually painful and severe, and go together with systemic manifestations that can involve various organs. Reactions to fire corals are also very severe. A correct diagnosis and appropriate treatment are essential in cases of cnidarian envenomations, particularly because specific antivenoms are lacking
Dermatitis caused by echinoderms
No full textThere are about 80 species of toxic or venomous Echinoderms. In particular, sea urchins, with their spine-covered bodies, are poisonous and can induce various types of reaction in man both when eaten as seafood and when they sting. In the first case, because of the toxins present in their gonads, the symptoms, although rarely fatal, will include gastrointestinal disorders and allergic reactions. Contact with the spines, that are sharp and very fragile, induces immediate and delayed reactions. Penetration of the spines into the skin causes immediate, burning pain, followed by erythema and edema, and there may be abundant bleeding from the affected part. Systemic symptoms can also develop, including nausea, muscle cramps, and respiratory distress. These symptoms can last up to 1-2 weeks, provided that the spines are immediately and completely removed. Delayed reactions are notoriously nodular granulomatous lesions, mostly considered to be non immunological reactions to a foreign body. Starfish can induce an urticarial clinical picture due to their toxins released in the water, as well as nodular granulomatous lesions after contact with the spines, that can be associated with very severe systemic symptoms. Again as a result of a toxic substance released into the water, seacucumbers can induce an irritant contact dermatitis and ocular lesions that can even end in blindness
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