Topics: Escherichia coli, Bacteria, Escherichia coli O157:H7 Pages: 6 (1616 words) Published: October 2, 2013
Delos Reyes, Donnaliza S. September 24, 2013 BSPT 13 Ms. Mae Maghari

Escherichia coli is a Gram-negative bacillus that is found in the GI tract of all humans. The strains and sero types of E. coli that are part of the indigenous microflora of the GI tract are opportunistic pathogens. They usually cause no harm while in the GI tract, but have the potential to cause serious infections if they gain access to the bloodstream, the urinary bladder or a wound.

Escherichia coli, also known as E. coli is a bacterium that is commonly found in the gut of endotherms (warm blooded organisms).

Several types of E. coli exist as part of the normal flora of the human gut and have many beneficial functions, such as the production of vitamin K2. They also prevent harmful bacteria, known as pathogenic bacteria, from establishing themselves in the intestine.

Most E. coli strains pose no harm to human health, except for serotype O157:H7, which can cause food poisoning in humans and can become life-threatening.

Other less common serotypes, such as O104:H4, O121, O26, O103, O111, O145, and O104:H21 can also cause serious infection.

According to Medilexicon's medical dictionary, 

Escherichia coli is:

"A species that occurs normally in the intestines of humans and other vertebrates, is widely distributed in nature, and is a frequent cause of infections of the urogenital tract and of neonatal meningitis and diarrhea in infants; enteropathogenic strains (serovars) of Escherichia coli cause diarrhea due to enterotoxin, the production of which seems to be associated with a transferable episome; the type species of the genus."

German pediatrician and bacteriologist, Theodor Escherich discovered the bacterium in 1885, hence its name. E. coli is now classified as part of the Enterobacteriaceae family of gamma-proteobacteria.

A healthy adult will usually make a full recovery from E. coli O157:H7 infection within 5 to 7 days. However, young children, elderly individuals and patients with weakened immune systems can develop potentially fatal HUS (hemolytic uremic syndrome), a type of kidney failure. Signs and symptoms of E. coli O157:H7 infection

The patient will typically experience symptoms within three to four days after being exposed to the bacteria, however, in some cases they may appear within a day or a week later.

The individual may experience:
Abdominal pain - typically, the first symptom is severe abdominal cramping that comes on suddenly. Diarrhea - a few hours after the sudden abdominal pain, the patient typically has watery diarrhea. A day later there may be bright red bloody stools, caused by sores in the intestines. Nausea

Vomiting - note that many patients who become ill may not vomit Fever - note that many infected people may not have a fever Fatigue - diarrhea causes loss of fluids and electrolytes (dehydration), making the patient feel sick and tired A considerable number of infected people have no noticeable symptoms. However, they are capable of unwittingly spreading the infection to others. What are the causes of E. coli O157:H7 infection?

Most strains of E. coli are harmless. However, one group, including 0157:H7, produces a potent toxin - Shiga toxin - that is harmful for the lining of the small intestine.

Humans can become infected by:
Ingesting contaminated water - even though tap water contains chlorine and has undergone ozone or ultraviolet treatment, some E. coli outbreaks have been caused by contaminated municipal water supplies. Private wells can be a source of infection, as can some lakes and swimming pools. Ingesting contaminated food - examples include ground beef, unpasteurized milk, or fresh vegetables. Infected people who work in restaurants and do not wash their hands properly after going to the toilet can spread the infection to customers and other members of staff. Having physical contact with an infected person, known as person-to-person...
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