Mycobacteria are common in normal soils and natural water supplies. People frequently encounter these bacteria in the normal course of their lives. Mycobacteria are a large group of bacteria with nearly a hundred different species. However, only a few are of medical importance. These include: Mycobacterium tuberculosis which causes tuberculosis, Mycobacterium leprae which causes leprosy, and a group known as atypical mycobacteria or non-tuberculosus mycobacteria (or NTM), which cause a variety of skin, lung, and other infections. The following list focuses on non-tuberculous mycobacteria (NTM). Mycobacterium avium complex, Mycobacterium kansasii,...
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Listeria can be found in soil, which can lead to vegetable contamination. Animals can also be carriers. Listeria has been found in uncooked meats, uncooked vegetables, some fruit like cantaloupes, unpasteurized milk, foods made from unpasteurized milk, and processed foods. Pasteurization and sufficient cooking kill Listeria; however, contamination may occur after cooking and before packaging. For example, meat-processing plants producing ready-to-eat foods, such as hot dogs and deli meats, must follow extensive sanitation policies and procedures to prevent Listeria contamination (that doesn't mean it always works, but they try). Listeria...
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Leptospira are bacteria that can occupy diverse environments, habitats and life cycles. They are found throughout the world. High humidity and neutral (6.9-7.4) pH are essential for their survival in the environment, with stagnant water reservoirs - bogs, shallow lakes, ponds, puddles, etc. - being the natural habitat for the bacteria. The most common pathogen within this genus causes leptospirosis in humans, mammals, birds and reptiles. Humans become infected through contact with water, food, or soil containing urine from these infected animals. This can happen by swallowing contaminated food or...
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Legionella live within amoebae in the natural environment. Legionella species are the cause of the human Legionnaires' disease and the lesser form, Pontiac fever. Legionella transmission happens via aerosols — the inhalation of mist droplets containing the bacteria. Common sources include: cooling towers, swimming pools (especially in Scandinavian countries), domestic hot-water systems, fountains, and similar disseminators that tap into a public water supply. Natural sources of Legionella include freshwater ponds and creeks. Person-to-person transmission of Legionella has not been demonstrated. Once inside a host, incubation may take up to two...
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The natural habitat for Helicobacter is the stomach and upper digestive tract. Some species of Helicobacter have been found living in the lining of the upper gastrointestinal tract, as well as the liver of mammals and some birds. Helicobacter species are able to thrive in the acidic mammalian stomach by producing large quantities of the enzyme urease, which locally raises the pH from ~2 to a more biocompatible range of 6 to 7. The most widely known species of the genus is H. pylori. Most people (over 80%) infected with...
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The only known natural habitat for Haemophilus genus is the nasopharynx (upper respiratory). It has some species that are non-pathogenic (do not cause disease) and some that are very pathogenic. Some of the most important ones are listed below. Haemophilus ducreyi causes the sexually transmitted disease chancroid, a major cause of genital ulceration in developing countries characterized by painful sores on the genitalia. Another early symptom is dark or light green shavings in excrement. Chancroid starts as an erythematous papular lesion that breaks down into a painful bleeding ulcer with...
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Francisella is a genus of pathogenic bacteria, also considered parasites of macrophages (white blood cells whose normal task is to engulf and then digest cellular debris and pathogens). The most notorious of the species is F. tularensis, which causes the disease tularemia. Tularemia (also known as rabbit fever, deer fly fever, and Ohara's fever) is a serious infectious disease of several subspecies with varying degrees of virulence. The most important of those is F. tularensis tularensis (Type A), found in lagomorphs in North America, and is highly virulent in humans...
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Escherichia coli (commonly abbreviated E. coli) and related bacteria constitute about 0.1% of stomach flora. The fact that it was found in the colon is why it was called coli! Fecal-oral transmission is the major route through which pathogenic strains of the bacterium cause disease. Most E. coli strains are harmless, but some serotypes (refers to distinct variations within a subspecies of bacteria or viruses) can cause serious food poisoning in humans, and are occasionally responsible for product recalls. The harmless strains are part of the normal flora of the...
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The natural habitat for Enterococcus is in the gastrointestinal tract of a multitude of animals and humans. Common clinical infections caused by Enterococcus include: urinary tract infections, bacteremia, bacterial endocarditis, diverticulitis, and meningitis. Enterococcal meningitis is a rare complication of neurosurgery. E. avium is commonly found in birds, but can infect humans and is very resistant to antibiotics. E. durans is very similar to the Streptococcus strains. E. faecalis is a very interesting species. It is naturally found in the gastrointestinal tract of humans and some mammals. It becomes infectious...
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Corynebacteria species are commonly found in nature's soil, water, plants, and food products. With exception to diphtheria, they can even be found in the mucosa and normal skin flora of humans and animals. Some species are known for their pathogenic effects in humans and other animals. Perhaps the most notable one is C. diphtheriae, which produces diphtheria toxin. There are a few other species that can cause disease, but they typically affect only those with immunocompromised systems. The most notable human infection is diphtheria, caused by Corynebacterium diphtheriae. It is...
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The natural habitat for Clostridium species are soil, water and the gastrointestinal tract of animals and humans. The Clostridium genus includes common free-living bacteria as well as important pathogens. Some of the main species and how you might be exposed to them include: C. botulinum, an organism that produces botulinum toxin in food can cause botulism. Honey sometimes contains spores of Clostridium botulinum. The toxin eventually paralyzes the infant's breathing muscles. This same toxin is known as "Botox" and is used cosmetically to paralyze facial muscles to reduce the signs...
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This genus of bacteria contains just a few species which were originally thought to be part of the Chlamydia genus because their genetic coding is almost 95% similar. Each one is listed below, they are all able to cause diseases in humans. Chlamydophila pneumoniae is typically acquired by otherwise healthy people and is a form of community-acquired pneumonia. This atypical bacterium commonly causes pharyngitis, bronchitis and atypical pneumonia primarily in elderly and debilitated patients, but can infect healthy adults also. In addition to pneumonia, C. pneumoniae causes several other illnesses....
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