Escherichia coli – Infection, Transmission & Diseases

Escherichia coli

Escherichia coli is actually a harmless intestinal dweller. As an opportunist, however, this germ is often diagnosed in the medical laboratory. Its distribution, pathogenicity and even the intended use of E. coli is as variable as the germ itself.

What is Escherichia coli?

Viewed under the microscope, Escherichia coli is a so-called “gram-negative rod bacterium”. It belongs to the enterobacteria family and is a member of the genus Escherichia . Most bacteria in this genus are motile and possess numerous other properties.

Among other things, E.coli has so-called “fimbriae” or “pili” with which it adapts to humanblood cellscan attach. But that’s not all: Many strains also have so-called “sex pili”: This allows gene information to be easily transferred that can give other bacteria advantages, such as resistance to many antibiotics . Another survival advantage is the active “pumping out” of toxins: Certain bacteria within the genus can also remove antibiotics from the cell interior.

This germ can exist in the presence or absence of oxygen, it is “obligate anaerobic”. E.coli therefore not only colonizes the intestines, but also wounds, the urinary bladder or, in the worst case, the blood of somepatientsin the intensive care unit.

Meaning & Function

Escherichia coli is not just the bad guy, but also an important part of the human intestinal flora. This microbe is therefore very important for human health and also produces vitamin K.

In newborns, it is often the first germ to colonize the body. E.coli is therefore even used as a medicine to build up a healthy intestinal flora after antibiotic therapy. Such as the isolated strain from the intestinal flora of a soldier who was apparently immune to diarrheal diseases . This special E.coli was not only particularly good at absorbing iron from food, but also protected its wearer against pathogens that would have caused diarrhea had it not been present.

But this microbe is not only important for the pharmaceutical industry as a probiotic: With the help of biotechnology, numerous medicines can be produced from E. coli. To do this, genes from other species can be introduced into the bacterial cell of specially bred and completely harmless E. coli, which contain specific information for proteins.

These are then produced, synthesized, so to speak, in the bacterium. And that in large quantities and with optimal tolerability, since E.coli, as a component of the human intestinal flora, hardly causes any allergies .


E.coli is normally a harmless bacterium. However, as an opportunistic pathogen, it finds small vulnerabilities in the host and generates infections. Uropathogenic E. coli (UPEC), play an important role in uncomplicated urinary tract infections .

A danger for newborns is E. coli of the “NMEC” type, which can cross the blood-brain barrier and is thus the trigger for neonatal meningitis . The variants of E. coli, which have an extended ß-lactamase spectrum (ESBL), are particularly difficult to treat, which is why an antibiotic test (antibiogram) should always be carried out in the case of infections with Escherichia coli.

The “pathogenic E.coli” occupy a special position in terms of the danger and relevance of these bacteria, which cause 160 million diseases worldwide every year and mean the death of a million people. Children under the age of five, who become infected with enteropathogenic E. coli (EPEC), especially in developing countries, are particularly affected. The next large group are the Enterotoxic E.coli (ETEC), which travelers very often suffer from.

The supply of electrolytes is important here, because “Montezuma’s revenge” and two different enterotoxins result in watery, extreme diarrhea . Enteroinvasive E. coli (EIEC) cause inflammation and ulcers in the stomach and intestines , respectively , because they invade the cells there directly. Enterohemorrhagic E. coli (EHEC) are particularly dangerous because their toxin can cause severe food poisoning .

Complications such as haemolytic uremic syndrome (HUS) are very feared here because they result in death from kidney failure in 10-30 percent of cases . Cattle are often reservoirs for pathogens, the faeces of which contain one to two percent EHEC bacteria, of which only 10-100 germs are sufficient for an infection.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.