General Information on Escherichia coli And K. SPECIES
The are some harmless strains which has been said to be part of a flora of the gut.
It has been assumed that it can benefit either from their host through the production of vitamin K2 according to Bentley and Maganathan in the year 2001, however, by preventing the proposed establishment engineered by the pathogenic bacteria that can be found within the intestine of an coli (Reld, et al., 2001). E. coli is gram-positive non-sporulating organism.
The cells are about 2µ long and 0.5µ in diameter with a cell volume of 0.6 to 0.7µm3 (Kubitshek, 1990). The optimal growth of E. coli occurs at 37C but some laboratory stains can multiply at temperature of up to 49C (Fotadar, et al., 2005).E. coli and related bacteria constitute about 0.1% of gut flora and faecal and transmission is the major route through which pathogenic strains of the bacterium cause diseases (Fenget al., 2002).
Some virulent strains of E. coli causes Gastroteritis, urinary tract infections and neonatal meningitis. Occasionally, you have a situation where virulent strains maybe responsible for the Hemolytic syndrome as experience by most as the (UUS) peritonitis carries all, and then the mastitis, and also a high level of gram-negative pneumonia which was propagated by Todar, in the year 2007). The Escherichia coli as has been propelled has a long but rapidly rotating flagella that are commonly found in lower intestine of warm blooded organisms(Fenget al., 2002).
Scientific Classification of E. coli
Specie Escherichia coli
History of E. coli
In 1885, Theodor Escherich, a german pediatrician, first discovered the species in the faeces of the healthy individual and called it bacteria coli due to the fact that is found in the colon and early classification of the prokaryotes placed these in group based on their shape and motility.
At that time, Ernst Haexkel classification of bacteria in the kingdom Monera was in place (Escherich, 1885). Bacterium coli were the specie of the now invalid genus bacterium. When it was revealed that former type species (bacterium triloculare) was missing (Breed and Conn, 2006), following a revision of bacteria, it was re-classified in the newly created genus Escherichia, named after its original discover (Migula, 1895).
Figure 1 showing Strains of E. coli bacteria
In May, 2001 one E. coli strain Escherichia coli 0104:114 has been the subject of a bacterial outbreak that began in Germany. Certain strains of Escherichia coli are major source of food borne illness. The outbreak started when several people in Germany infected with enterohaemorrhagic E. coli (EHEC) bacteria, leading to haemolytic Uremic Syndrome (HUS), a medical emergency that required urgent treatment.
The outbreak did not concern only Germany but 11 other countries including regions in North America. On 30th June 2011, the German Bundesinstitute Fur Risikobewenting (BFR) (Federal Institute for Risk Assessment, a federal fully legal entity under public law of the Federal Republic of Germany Ministry of Food, Agriculture and Consumer Protection) announced that seeds of fenugreek from Egypt were likely the cause of EHEC outbreak (Ingledew and Poole, 1984).
Biology and Biochemistry of Escherichia coli
Escherichia coli as has been reported has the capacity to live on any wide range in the variety of substances made available. Escherichia coli makes uses of mixed-acid that has undergone a prolonged fermentation and is now in an anaerobic conditions, this will now be making it to be producing a lactate, as well as a succinate and then a high level of carbon dioxide.
Since the required pathways in the mixed-acid which is gotten by a prolonged fermentation which produce hydrogen to be low, as is the case when E. coli lives together with hydrogen –consuming organisms such as methanogan or sulphate reducing bacteria (Kubitschek, 1990) (Madigan and Martinko, 2006). The calculated optimal growth of the Escherichia coli occurs at about 37C in most cases but some highly equipped laboratory strains can also multiply at temperature of up to 49C driven by aerobic or anaerobic respiration, using a large variety of redox pairs these includes the un-calculated oxidation that could be experienced by the pyruvic acid as the case maybe, as well as the formic, with a high level of hydrogen as well as an amino acid and then we have a reduction of an substrates which will then include oxygen, dimethyl-sulfoxide and also a trimethylamine N-oxide or maybe an nitrate plus fumarate according to Ingledew and Poole, in the year 1984. Strains that posses flagella are motile.
The flagella have a petrichous arrangement (Daraton, et al., 2006).E. coli and related bacteria posses the ability to transfer DNA via bacterial conjugation, transduction or transformation, which allows genetics materials to spread horizontally through an existing population (Brossow, etal., 2004).
Culture of Escherichia coli
- coli produce 1-4mm in diameter colonies after overnight incubation. Some strains are haemolytic. On MacConkey agar, Escherichia coli ferments lactose, producing smooth ink colonies.
Morphology of Escherichia coli
Escherichia coli is a gram-ve usually motile rod. Inactive strains are non-motile. A majority of stains are capsulate.
Virulence properties of Escherichia coli
Entric E. coli (EC) are classified on the basis of serelogical characteristics and virulence properties (Todar, 2007). Virotypes include:-
Enterotoxigenic E. coli (ETEC): Is the causative agent of diarrhea (without fever) in humans, pig, sheep, goat, cattle, dog and horse. ETEC uses fimbrial adhesions (projection of bacterial cell surface) to bind enterocyte cells in the intestine. ETEC can produce two proteinaceous enterotoxins: (1) The larger of the two protein, LT enterotoxin is similar to cholera toxin in structure and function (2) The smaller protein, ST entotoxin causes GMP accumulation in the target cells and a subsequent secretion of fluid and electrolytes into the intestinal lumen.
Enteropathogenic E. coli (EPEC): Is the causative agent of diarrhea in humans, dogs, rabbits and horses. Like ETEC, EPEC also cause diarrhea but the molecular mechanism of colonization and actiology are different. EPEC lacks fimbrae, ST and LT toxins, but they use an adhesion known as intimin to bind host intestinal cells. The viotype has an array of virulence factors that are similar to those found in shigella and may possess a shiga toxin. There is an adherence to intestinal mucosa which is mostly caused by the rearrangement of an acting host cell, these has resulted by the causing on of a significant deformation in it.
Diseases Associated with E. coli
Escherichia coli comprise up to 1% of the total amount of bacteria in the intestine. Most strains of Escherichia coli are harmless while other strains of E. coli produce toxins that cause several types of disease in humans.