examples of Gram negative bacteria


Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall sandwiched between an inner cytoplasmic cell membraneand a bacterial outer membrane.

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Escherichia coli or Escherichia coli (scientific name: Escherichia coli)

is one of the most important types of bacteria that live in mammals. Discovered by Theodore Church. It is also known as the large intestine germ. Escherichia coli is a Gram-negative bacterium that lives in the large intestine of humans, and about 80% of its structure is aerobic bacteria. Note that anaerobic bacteria are prevalent in their intestines. The presence of these bacteria in the surrounding environment indicates the presence of fecal contamination, so it is often used as an indicator to indicate water contamination, and to judge whether it is safe to drink or not.

Rickettsia is a genus of nonmotilegram-negativenonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The term "rickettsia" has nothing to do with rickets (which is a deficiency disease resulting from lack of vitamin D); the bacterial genus Rickettsia instead was named after Howard Taylor Ricketts, in honor of his pioneering work on tick-borne spotted fever.

Rickettsia species are transmitted by numerous types of arthropod, including chiggerticksfleas, and lice, and are associated with both human and plant diseases. Most notably, Rickettsia species are the pathogens responsible for typhusrickettsialpoxboutonneuse feverAfrican tick-bite feverRocky Mountain spotted feverFlinders Island spotted fever, and Queensland tick typhus(Australian tick typhus).The majority of Rickettsia bacteria are susceptible to antibiotics of the tetracycline group.

Mycoplasmataceae is a family of bacteria in the order Mycoplasmatales. This family consists of the genera Mycoplasma and Ureaplasma. Mycoplasmatales was incorporated into the class Mollicutes.Many species are sexually transmitted and cause pelvic inflammatory disease. Mycoplasma refers to a genus of bacteria that lack a cell wall and possess a three-layered cellular membrane.They can be parasitic or saprotrophic. Several species are sexually transmitted and pathogenic in humans. Others are found on cats, dogs, and barnyard fowl. Ureaplasma is urease positive.

Campylobacter (meaning "curved bacteria") is a genus of Gram-negative bacteria.Campylobacter typically appear comma- or s-shaped, and are motile. Some Campylobacter species can infect humans, sometimes causing campylobacteriosis, a diarrhoeal disease in humans.Campylobacteriosis is usually self-limiting and antimicrobial treatment is often not required, except in severe cases or immunocompromised patients. The most known source for Campylobacter is poultry, but due to their diverse natural reservoir, Campylobacter spp. can also be transmitted via water. Other known sources of Campylobacter infections include food products, such as unpasteurised milk and contaminated fresh produce.Sometimes the source of infection can be direct contact with infected animals, which often carry Campylobacter asymptomatically.At least a dozen species of Campylobacter have been implicated in human disease, with C. jejuni(80–90%) and C. coli (5-10%) being the most common. C. jejuni is recognized as one of the main causes of bacterial foodborne diseasein many developed countries. It is the number one cause of bacterial gastroentritis in Europe, with over 246,000 cases confirmed annually. C. jejuni infection can also cause bacteremia in immunocompromised individuals, while C. lari is a known cause of recurrent diarrhea in children. C. fetus can cause spontaneous abortions in cattle and sheep, and is an opportunistic pathogen in humans.

Borrelia is a genus of bacteria of the spirochete phylum.Several species cause Lyme disease, also called Lyme borreliosis, a zoonoticvector-borne disease transmitted by ticks. Other species of Borrelia cause relapsing fever, which are transmitted by ticks or lice, depending on the species of bacteria.The genus is named after French biologist Amédée Borrel (1867–1936), who first documented the distinction between a species of Borrelia, B. anserina, and the other known type of spirochete at the time, Treponema pallidum.This bacterium must be viewed using dark-field microscopy, which make the cells appear white against a dark background. Borrelia species are grown in Barbour-Stoenner-Kelly medium. Of 52 known species of Borrelia, 20 are members of the Lyme disease group (with an additional 3 proposed), 29 belong to the relapsing fever group, and two are members of a genetically distinct third group typically found in reptiles. A proposal has been made to split the Lyme disease group based on genetic diversity and move them to their own genus, Borelliella, but this change is not widely accepted. This bacterium uses hard and soft ticks and lice as vectors. Testing for the presence of the bacteria in a human includes two-tiered serological testing, including immunoassays and immunoblotting.


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