Examples of Gram Negative Bacteria
Gram negative bacteria cause infections, such as cholera, typhoid, meningitis and various kinds of gastrointestinal distresses. Secondary infections in hospitals are usually a result of an infection by a Gram negative bacteria. Here is a list of Gram negative bacteria, including a brief account of their structure, functions and medical significance.
1. Salmonella - Salmonella are a genus of rod-shaped bacteria. They are non-spore forming enterobacteria with flagella. They oxidize and reduce organic substances and, in the process, produce hydrogen sulfide. Salmonella are found throughout the animal kingdom. They normally live within the intestinal tract of birds and other animals and can spread from animals to humans through the consumption of contaminated milk, eggs, poultry and beef. Nausea, vomiting, diarrhea and fever are common symptoms in humans who have Salmonella.
2. Shigella - Shigella are a genus of rod-shaped Gram negative bacteria. Similar to Salmonella, they are non-spore forming. They only affect primates and not other mammals. Shigella are the cause of Shigellosis in humans. They also cause diarrhea and dysentery and can be spread from person-to person via contact and through ingestion of contaminated food and water. They destroy the cells that line the large intestine, resulting in ulceration and bloody diarrhea.
3. Escherichia Coli - E.Coli, as they are commonly known, are a rod-shaped Gram negative bacteria. E.coli are non-sporulating. They can grow aerobically or anaerobically and cause the reduction of substrates, such as oxygen and nitrates. Although most strains of E.Coli are not harmful and are present in the gut of humans a few hours after childbirth, certain E.Coli strains can produce toxins that are lethal and can be dangerous. They can cause urinary tract infections, neonatal meningitis, food poisoning and serious complications, such as Hemolytic-uremic syndrome, in humans. The consumption of vegetables that are not properly washed and meat that has not been cooked thoroughly can result in E.Coli infections. E. Coli infections have also be known to occur from eating Hazelnuts.
4. Helicobacter - Helicobacter are a genus of Gram negative bacteria shaped in the form of a helix. The species H.Pylori is of particular interest to bacteriologists and gastroenterologists, as it infects nearly 50% of humans. H.Pylori generally metabolize nitrogen. The lipopolysacchride that helicobacter contain has unique biological properties. Flagella help them to be motile and move fast. Certain species of helicobacter are known to cause peptic ulcers, gastritis and stomach cancer.
5. Acetic acid bacteria - Acetic acid bacteria are rod-shaped Gram negative bacteria. These bacteria are so named as they oxidize ethanol to acetic acid during the process of fermentation, from which they derive their energy. They are present in nature, in flowers and fruits, and are an important part of the food industry. Wine fermentation also makes use of acetic acid bacteria, which are generally harmless to humans.