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  1. Escherichia coli (/ ˌ ɛ ʃ ə ˈ r ɪ k i ə ˈ k oʊ l aɪ /), also known as E. coli (/ ˌ iː ˈ k oʊ l aɪ /), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms.

  2. › wiki › Gram_stainGram stain - Wikipedia

    Gram stain or Gram staining, also called Gram's method, is a method of staining used to classify bacterial species into two large groups: gram-positive bacteria and gram-negative bacteria. The name comes from the Danish bacteriologist Hans Christian Gram , who developed the technique.

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    When did Hans Christian Joachim Gram discover the Gram stain?

    How is Gram stain used in bacteriological laboratory?

    Why do cattle have Escherichia coli O157 H7?

    What kind of shape does Escherichia coli have?

  4. E. coli O157:H7 contains 463 phage-associated genes compared with only 29 in E. coli K-12 . A change in G+C contents is one of the indications that a genomic region has been acquired by horizontal transfer, and Putonti et al. [ 55 ] estimated that at least 53 different species have contributed to these unique sequences in E. coli O157:H7.

    • Ji Youn Lim, JangWon Yoon, Carolyn J. Hovde
    • 414
    • 2010
  5. Oct 09, 2020 · MPN - Completed test for E. coli. To perform the completed test for E. coli, gently agitate each gassing EC tube, remove a loopful of broth and streak for isolation on a L-EMB agar plate and ...

    • Escherichia Coli
    • E. Coli Habitat
    • E.coli Morphology and Arrangement
    • Cultural Characteristics of E. Coli
    • Toxin of E. Coli
    • Clinical Infections of E. Coli
    • Laboratory Diagnosis of Escherichia Coli
    • Treatment of E. Coli Infections
    • Prevention and Control of E. Coli Infections
    • Medical Importance of E. Coli
    Theodor Escherich first discovered E. coli, in 1885 after isolating it from the feces of newborns.
    Escherichia coli also termed E. coli, which is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus Escherichia.
    It is usually found in the lower intestine of warm-blooded organisms (endotherms).
    Most E. coli strains are harmless, however, some serotypes (EPEC, ETEC etc.) are responsible for serious food poisoning in their hosts. They also occasionally cause food contamination incidents tha...
    The availability of the nutrients within the intestine of host organisms is the main factor on which the niche of E. coli depends.
    The gastrointestinal (GI) tract of humans and many other warm-blooded animals is the primary habitat of E. coli.
    They can be found in the mucus or the epithelium on the wall of the intestine. Commonly they are found in the colon of the large intestine.
    They can form a mutual relationship with its host.
    E.coli is a gram-negative (-ve) bacteria.
    These are straight, rod shaped (bacillus) bacterium.
    They are arranged singly or in pairs.
    Their size is about 1–3 µm × 0.4–0.7 µm (micrometer).
    Escherichia coli or E. coli can grow on ordinary media like Nutrient Agar medium (NAM).
    Commonly the NAM & MacConkey Agar medium is used for the cultivation of Escherichia coli in the Laboratory.
    The optimum temperature required for most of the E.coli strains is 37°C.
    E. coli can survive at 4.5– 9.5 pH but the optimum pH is 7.0.

    Except endotoxin associated with O antigen, some E. coli strains produce two types of exotoxin such as enterotoxin and haemolysin. Enterotoxins 1. Enterotoxins cause diarrhea, these are of two types such as heat labile (LT); heat stable (ST). 2. The LT is similar to cholera enterotoxin which is similar antigenically and in its mechanism of action. It acts by stimulating the adenyl cyclase—cyclic adenosine monophosphate (cAMP) system to produce fluid accumulation in the intestinal lumen. 3. ST stimulates fluid secretion into the gut by the mediation of cyclic guanosine monophosphate (cGMP) resulting in dehydration. Haemolysin 1. E. coli produced 3 types of hemolysins which are not related to pathogenesis. 2. E. coli produces a part of normal intestinal flora of man and animals and the commensal strains belong to several O groups. 3. There are many strains of E. coli which include commensal strains as well as strains with virulence determinants that cause a wide variety of infections...

    The virulent form of E. coli found in the gut (enteritis) and of extra-intestinal sites (urinary tract infection, wound infection). The pathogenic form of E. coli is responsible for these following infections; 1. Urinary tract infection (UTI) 2. Septic infections of wound 3. Diarrhoea 4. Dysentery 5. Septicaemia 6. Pneumonia 7. Neonatal meningitis 8. Abscess in various organs. There are four groups of E. coli which are responsible for diarrhoea in infants, children and adults are such as Enteropathogenic E. coli (EPEC); Enterotoxigenic E. coli (ETEC); Enteroinvasive E. coli (EIEC); Enterohaemorrhagic E. coli (EHEC).


    1. To detect the EPEC, fresh diarrhoeal stool is plated directly on blood agar and MacConkey agar medium. 2. After overnight incubation, E. coli colonies are emulsified in saline on a slide and tested by agglutination with polyvalent and monovalent O antiserum against entero-pathogenic serotypes and further identified by biochemical tests. 3. Enzyme linked immuno-sorbent assay (ELISA) test is simplest and used to detect LT of ETEC. 4. LT and cholera entero-toxin are antigenically similar. Ser...

    Urinary Tract Infection

    1. Most of the urine specimens are collected from adult patients by the clean-catch midstream technique. 2. The detection of bacteria can be done microscopically by using Gram staining of uncentrifuged urine specimens, Gram staining of centrifuged specimens, or direct observation of bacteria in urine specimens. 3. During the staining procedure the E coli appears as a non-spore-forming, Gram-negative rod-shaped bacterium. 4. During the semi-quantitative method the routine urine cultures should...

    Other Test/ Reactions

    1. E. coli typically produces positive test results for indole, lysine decarboxylase, lactose, and mannitol fermentation and produces gas from glucose. 2. An isolate from urine can be quickly identified as E. coli by its hemolysis on blood agar, typical colonial morphology with an iridescent “sheen” on differential media such as EMB agar, and a positive spot indole test result. 3. More than 90% of E. coli isolates are positive for β-glucuronidase using the substrate 4-methylumbelliferyl-β-glu...

    Different antibacterial medicines can be used such as sulfonamides, ampicillin, cephalosporins, fluoroquinolones, and aminoglycosides.
    E. coli meningitis needs antibiotics, like as third-generation cephalosporins (eg, ceftriaxone).
    Respiratory support, adequate oxygenation, and antibiotics, such as third-generation cephalosporins or fluoroquinolones are required for E. coli pneumonia.
    In case of diarrheal disease the patient should drink plenty of fluids to avoid dehydration and to get as much rest as possible. Avoid dairy products, these may induce temporary lactose intolerance...
    It is universally suggested that attention be observed in regard to food and drink in areas where environmental hygiene is inadequate and that early and brief treatment (eg, with ciprofloxacin or t...
    We can control E. coli infections by handwashing, rigorous asepsis, sterilization of equipment, disinfection, restraint in intravenous therapy, and strict precautions in keeping the urinary tract s...
    E. coli is used to produce insulin vis adopting the genetic engineering technique.
    In intestine, it Produces certain vitamins.
    It is used as a parameter to determine the fecal contamination of drinking water.
    In bacterial genetics, it is used for the plasmid study.
  6. The most widely used staining procedure in microbiology is the Gram stain, discovered by the Danish scientist and physician Hans Christian Joachim Gram in 1884. Gram staining is a differential staining technique that differentiates bacteria into two groups: gram-positives and gram-negatives.

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