Escherichia coli is a group of bacteria that has gained significant attention due to its dual nature. Most of the E.coli strains are harmless commensal organisms but there are strains which act as potential pathogens. Since there is an association between this bacteria and human health, we should be aware about this bacterium. Here we focus on the interesting facts about E. coli and how to manage the strains that affect our health.
Characteristic features of E. coli
- Gram-Negative: E. coli has a thin layer of peptidoglycan and outside this is an outer membrane composed of lipopolysaccharides. Which stains pink during the Gram stain test.
- Rod-Shaped: The dimensions of the cylindrical bacterium are usually about 2.0 micrometers in length and 0.5 micrometers in diameter.
- Facultative Anaerobe: It can grow both in the presence and in the absence of oxygen, so it grows well in different environments.
- Motile and Non-Motile Strains: Some E. coli strains are motile due to the presence of flagella, while others are non-motile.
- Optimal Growth Temperature: The optimum temperature for growth is at the human body temperature, about 37°C.
- Rapid Growth: Growth is very fast and one of the facts about E. coli is that its population can double every 20 minutes.
- Central metabolism: The core of central metabolism in E. coli includes pathways like glycolysis, the TCA cycle and the pentose phosphate pathway, which supply energy and precursor metabolites during growth and for maintenance.
- Diverse strains: This group of bacteria includes both commensal as well as pathogenic strains.
The Commensal E. coli
The commensal E. coli strains are the inhabitants of the intestines of humans and other warm-blooded animals where they promote good intestinal health and digestion. By occupying niches in the gut, commensal E. coli strains exclude or prevent the colonization of pathogenic bacteria and so protect the host from infections.
The Pathogenic E. coli
The pathogenic strains of E. coli have major public health implications. These are further classified based on the mechanisms by which they cause disease and their clinical manifestations. These include –
- Enteropathogenic E. coli (EPEC): EPEC is known for causing diarrhea in infants in developing countries. It adheres to the intestinal epithelium, leading to the destruction of microvilli and malabsorption of nutrients.
- Enterohemorrhagic E. coli (EHEC): EHEC, such as the notorious O157 strain, produces Shiga toxin, causing bloody diarrhea and potentially leading to hemolytic uremic syndrome (HUS), which can result in kidney failure.
- Enterotoxigenic E. coli (ETEC): ETEC produces toxins that stimulate the lining of the intestines, causing severe watery diarrhea. It is a common cause of traveler’s diarrhea.
- Enteroinvasive E. coli (EIEC): EIEC invades intestinal cells, leading to symptoms similar to dysentery, including bloody diarrhea and high fever.
- Enteroaggregative E. coli (EAEC): EAEC forms a biofilm on the intestinal lining, causing prolonged diarrhea in children and adults.
Infection and Transmission
The transmission of pathogenic E. coli occurs via contaminated food or water, direct contact with an infected individual and even animal feces. Sources include undercooked ground beef, raw unpasteurized milk and fresh produce. The infection can cause symptoms that vary depending on the type, but the common symptoms generally include –
- diarrhea,
- abdominal cramps,
- nausea,
- vomiting,
- In severe cases, especially with EHEC infections, symptoms can progress to hemolytic uremic syndrome (HUS).
Prevention: Understanding the facts about E. coli helps in preventing and managing foodborne illnesses. The infections can be prevented by –
- proper food handling practices, such as thoroughly cooking meat,
- avoiding unpasteurized dairy products,
- washing fruits and vegetables,
- practicing good hygiene etc.
Other interesting facts about E. coli
- Vitamin K Production: E.coli contributes to vitamin K production in the human intestine.
- Biofilm Formation: Forms biofilm on most surfaces, which helps in its survival and gives resistance to environmental stresses.
- Model Organism: One of the key facts about E. coli is that the bacterium plays a prime role in scientific research due to its simple genetics, fast growth rate and manipulation efficacy.
- Recombinant DNA Technology: E. coli can be genetically engineered to produce recombinant proteins to be used in research. For e.g. recombinant insulin, growth hormones and other therapeutic proteins have been produced by engineering the genetic material of E.coli.
- Biotechnology Applications: Besides application in medical fields, E. coli has contributed to biofuel, bioplastics and other industrial production purposes.
- Quality Control: Strains like E. coli ATCC 8739 are used to test the quality of sterile products and to assess disinfectant efficacy.
- Antimicrobial Susceptibility Testing: E. coli plays a critical role in antibiotic susceptibility evaluation for developing novel antimicrobial therapies.
- Genetic Adaptability: Through its ability to pick up and exchange genes, E. coli adapts to heterogeneous environments that enable it to persist and sometimes cause pathology.
- Environmental Monitoring: E. coli acts as an indicator organism with regard to fecal contamination of water. This fact about E. coli indicates that this bacterium can help to evaluate the safety of water, hence preventing water-borne diseases.
By understanding the multifaceted facts about E. coli, we can appreciate its importance and harness its capabilities while mitigating the risks associated with its pathogenic strains. This knowledge is integral to advancements in health, science and industry, underscoring the bacterium’s complex and vital role in our world.
Use of E. coli (ATCC 8739) at MIS Lab
Microbe Investigations Switzerland (MIS) is a leading global provider of premium testing and validation services. At MIS, the E. coli strain is used as a test organism for assessing the antibacterial efficacy of products like textiles, plastics, coatings and disinfectants. This strain is well-characterized and widely used in quality control and research.
The key test methods followed include:
- EN 1276 – The EN 1276 is a quantitative suspension test for the evaluation of the bactericidal activity of chemical disinfectants and antiseptics. This is particularly useful across food, industrial, domestic and institutional sectors.
- ISO 22196 – ISO 22196 is a quantitative test used to determine the antimicrobial activity of antibacterial-treated plastic materials to kill bacteria (bactericidal) or inhibit their growth (bacteriostatic).
- AATCC 100 – The AATCC 100 is a quantitative test method used to determine the antibacterial activity of a textile or porous material, such as paper filter media and tissues.
In addition, we use E. coli strain (ATCC 8739) along with other test organisms (requested by clients) to perform the antimicrobial susceptibility assays such as Minimum Inhibitory Concentration (MIC) and Zone Of Inhibition (ZOI).
FAQs
What are the unique characteristics of E. coli?
Escherichia coli (E. coli) is a gram-negative, rod-shaped bacterium commonly found in the intestines of humans and animals. It exhibits rapid growth and reproduction under favourable conditions, often within 20 minutes
Is E. coli a facultative anaerobe?
Yes, E. coli is an example of a facultative anaerobe which is one of the interesting facts about E coli. It can grow both in an aerobic environment or an anaerobic one.
How can E. coli contamination be detected in food and water?
Laboratories use microbiological testing methods such as culture tests and polymerase chain reaction (PCR) to detect E. coli contamination.
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