Descriptions Of The Microbe Escherichia Coli Biology Essay


Escherichia coli otherwise referred to as E. coli are gram negative bacteria which are commonly located within the lower intestine of people, animals and also in there faeces. There are over 700 strains of E. coli, making up the gut flora most of which do not cause infection. Some types of E. coli can cause serious disease when it leaves the intestine and spreads. The toxins released by the bacteria damage the gut walls mucosal cells and vascular endothelial cells. An infection to the bladder or kidney is when the bacteria spread to the urinary tract and cause infections. E. coli can also cause food poisoning or diarrhoea, as the bacteria can survive a short amount of time outside of the body with or without oxygen. E.coli can be found in high temperatures like at the edge of a spring. Also E. coli can be used as an indicator organism to measure facial contamination in an environment like how much contamination there is in water.

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Furthermore there are six groups of enterovirulent E. coli strains or EEC E.

ETEC (enterotoxigenic E. coli) Affects humans and animals with watery diarrhoea with no fever, infants and travelers

EPEC (enteropathogenic E. coli) Affects humans and some animals with diarrhoea (may release shiga-toxins)

EIEC (enteroinvasive E. coli Only found in humans, with severe diarrhoea and high fever

EHEC (enterohemorrhagic E. coli) Affects Humans and some animals has strain O157:H7, causes bloody diarrhoea and no fever, can cause kidney failure and release Shiga toxin. Strain is caught from uncooked beef enters the body by faecal-oral route.

EAEC (enteroadherent E. coli Affects humans only causing watery diarrhoea

However E. coli helps people and animals produce vitamin K food, breakdown of the food we eat, its absorption and assists in its disposal.

E. coli are typically rod shaped about 2 micrometres length and 0.5 micrometres in diameter, some have flagella that allow the bacterium to move and attach to cells. The bacteria have a single circular chromosome. The strains of E. coli differ in their genotype which affects its phonotype. This allows the different bacterium’s to survive in different environments or animals. The transfer of bacterial DNA plasmids allows more useful strains to populate and survive.

The E. coli that is found in human large intestine is called enteroaggregative E. coli, whilst Escherichia coli are found in humans and mammals. .

A strand which is dangerous to humans E. coli O157:H7 and can cause serious illness and is very infective causing food poisoning. This strand releases lethal toxins Shiga-like toxin. This blocks the production of mRNA translation meaning cell death. This can cause symptoms like diarrhoea, cramping of the stomach, vomiting and fever. In a healthy person this can last for several days. This strand is dangerous because it only needs to infect 10 â€" 100 organisms rather than thousands to millions.

Transmission of E. coli general comes from eating uncooked meat / unwashed vegetables, food preparation, drinking un-pasteurised (raw) milk, drinking water which is not clean or has traces of faeces in it. This is because E. coli bacteria can contaminate the meat in the slaughtering process and be mixed in to the meat. The meat should be cooked at high temperatures to remove the bacteria and also for a long enough time. The germ can also be passed person to person.

There are many infections linked with E. coli from Acute bacterial meningitis, Intra-abdominal infections, Enteric infections, Urinary tract infections and many other miscellaneous infections.

Acute bacterial meningitis is the inflammation of meninges membranes, which cover the central nervous system, spinal cord and the fluid which floats around the brain or spinal cord. Most of the time, this meningitis is a virus or bacteria. This is important to know as treatments can differ. The bacterium affects the meninges membranes by entering the body via a fracture in the skull or in surgery and gets transported through blood stream also through contact with faeces. In most cases the bacteria affects the upper lungs and symptoms last for around 72 hours. Symptoms can be a high temperature above 39ÌÅ  C, headaches, neck stiffness are positive signs of Acute bacterial meningitis. The infection can be removed with antimicrobial therapy, penicillin is the drug used in treatment.

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A sample of the cerebrospinal fluid is isolated for identification through a simple procedure spinal tap, where a needle is inserted in to your lower back to remove some of the fluid for inspection. A culture of the fluid is inspected.

One in four people with acute bacterial meningitis die. The most common treatment used is antibiotics (penicillin G) and is started even before results of diagnostic tests.

As doctors do not know the bacteria causing the infection in the early stages of treatment many different antibiotics are used. Once the bacteria has been identifies an antibiotic which is most effective is used and any unnecessary ones are stopped. A corticosteroid that stops inflammation is given soon after, to reduce pressure in the skull. If any adrenal glands are damaged these are also is repaired, this treatment normally lasts for around 2 to 4 days. In this time the fluids lost from the body are replaced, due to the fever, vomiting, sweating and a loose in appetite. If treatment is delayed problems like loss in hearing, permanent brain damage is likely. Vaccinations are given to those with a weak immune system.

An Intra-abdominal infection occurs in the spillage of the gut organisms through the GI tract or necrotic gut wall. This creates a passage for the bacteria to leave the intestine.

Urinary tract infections are the most common type of healthcare-associated infection, accounting for more than 30% of infections reported by acute care hospitals. ( the urinary system is the ureters, urethra, bladder, and kidneys. An infection happens when bacteria from the digestive tract divide and multiple by the urethra. Urethra allows the urine from the bladder to escape out of the body by allowing urine to flow through it. The bacteria can then travel up the urethra towards the bladder and then towards the kidneys if left untreated. The symptoms are the urge to urinate frequently which is painful, despite this only small amounts of urine is released which has a milky or reddish look. A patient can be diagnosed by a simple examination of the urine under a microscope, and a few chemical reactions. The urine is looked over to see the red and white blood cells, the bacteria are also grown in a culture with different antibiotics to find the best drug to kill of the bacteria. Cystourethrography shows any changes in the urinary system. X-rays can be used to see the infected bladder or kidney and ureters and show any changes in the tract. A dye is injected into the bladder. This is x-rayed before and after the person urinates. Also radioactive substance with a low half-life can be placed in the bladder but a nuclear scanner is used.

Diagnosis of E. coli is usually culturing on sorbitol-MacConkey medium and then using typing antiserum.

Researchers are currently trying to produce vaccines to lower the worldwide rate of E. coli disease.