Pathogen Escherichia coli Article 2022

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TITLE
NAME
CHAMBERLAIN UNIVERSITY
DATE

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Abstract
The article is proposed to provide a brief insight about the pathogen Escherichia coli, its
classification and morphological characters, along with the suitable growth conditions and
nutritional needs. It also discusses about the pathogenicity of the bacteria, along with the
virulence factors and the type of disease it produces within the host. The symptoms, diagnosis
and therapeutic intervention for the treatment of the disease is also explained in details.
Article Summary
E.coli is a gram-negative pathogenic bacteria which is found in the human intestine. The toxic
and pathogenic strains of E,coli causes severe gastrointestinal problems such as diarrhea and
urinary tract infection. It is a mesophile and can grow at moderate temperatures. It is a
facultative anaerobe and can grow in absence of oxygen. It causes gastrointestinal problems in
human as well as urinary tract infection. It is sensitive to quinolones and aminoglycosides,
however some strains of E.coli exhibit multi drug resistance.
Pathogen Information
Classification of microorganism
Escherichia Coli is an unicellular, prokaryotic bacteria since it does not have a nucleus with a
distinct nuclear membrane, nor does it have any specialized cellular organelles, instead it has a
genetic material called “nucleoid”. It belongs to the genus “Escherichia” and family of
“Enterobacteriaceae”. It is a gram negative, rod shaped bacteria. It does not produce spores,
thus it is a non-spore forming microorganism, some of them contains peritrichous flagella for
mobility while the others are non-motile, presence of fimbriae is also common in some strains.
Few strains of E.coli consist of polysaccharide capsule, which increases its pathogenicity and
also protects the bacteria from getting engulfed by macrophages, thus preventing phagocytosis.
They are facultative anaerobes, which means that they are able to produce in presence or
absence of oxygen through aerobic or anaerobic respiration respectively.

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Cellular/ structural (in case of viruses) characteristics.
Escherichia coli is a gram-negative rod shaped prokaryotic bacteria. The gram staining is a type
of differential staining which helps in the differentiation between a gram-negative bacteria and
gram negative. On gram staining, it takes up the gram-negative stain (saffranin) and appears
reddish pink. Since it is a gram-negative rod, it has a very thin peptidoglycan layer. It mainly
contains an outer layer consisting of phospholipids and polysaccharides, which gives a overall
negative charge to the bacteria. As a result, it does not retain the Gram-positive crystal violet
strain.
Susceptibility to antibiotics/ antiviral or antifungals
E.coli is found to be sensitive against antibiotics such as norfloxacin, ciprofloxacin, gentamicin
and chloramphenicol. Ciprofloxacin and norfloxacin belongs to the class of Quinolone
antibiotics, whereas, gentamicin belongs to the class of aminoglycoside antibiotics. The
quinolones restricts bacterial growth by inhibiting replication of bacterial DNA by preventing the
unwinding of the DNA through disruption of the action of DNA gyrase or Topoisomerase which
induces a negative supercoiling of the DNA and thus relaxes the DNA. It is bactericidal in
nature. The aminoglycosides are protein synthesis inhibitor which disrupts the synthesis of
protein of the bacteria by binding to the 30S ribosomal subunit, inhibiting the translocation of
peptidyl tRNA from the A-site to the P-site of the ribosomal subunit, thus leading to misreading
of the genetic code. However, it is found that E.coli is getting resistant to antibiotics by
producing extended spectrum beta lactamase, which is an enzyme responsible for antibiotic
ineffectivity and helping the bacteria to exhibit multi drug resistance.
Growth conditions
E.coli is a mesophile, which grows best around 20-370Celsius. It grows in a neutral pH
environment. E.coli is also known as gut bacteria, as it resides inside the gut of the human
body, where the temperature is around 370Celsius. It is a facultative anaerobe and is able to

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grow without the presence of oxygen through anaerobic respiration, however its growth rate is
increased if oxygen is available.
Evasion of immune system
The E. coli strain O157:H7 causes infection by disrupting the immune system of the host(Wasey
& Salen, 2019). These bacteria secretes a specific protein NIeH1 which alters the immune
enzyme of the host. As a result, the bacterium evades the immune system of the host as well as
extends their survival within the host, enabling the bacterium to persist and show its virulence
and cause infection within the host. The virulence factors of the pathogenic strains of E.coli are:
Endotoxins secreted from the LPS layer are responsible for inducing pathogenicity,
polysaccharide capsule, which interferes with the antimicrobial activity, Fimbriae or pili, which
helps in the attachment of the bacteria into the host surface, siderophores for the transport of
iron molecules across cell membrane and lastly the drug resistant plasmids.
Disease(s) caused
Since, E.coli is present in the gastrointestinal tract of the humans, it is responsible for
gastrointestinal problems such as traveler’s diarrhea(Cabal et al, 2016). It also causes UTI
(Urinary Tract Infection), septicemia and other clinical infections such as meningitis or
pneumonia.
Symptoms
The symptoms of traveler’s diarrhea are:
 Fever
 Nausea and Vomiting
 Abdominal bloating
 Abdominal cramp
 Malaise or weakness
 Frequent release of watery and profuse stools

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Diagnosis
The diagnosis of Traveler’s diarrhea can be done by:
 Assessing the longevity of diarrhea whether it persist for more than 2 days
 Assess for abdominal pain or discomfort
 Check the frequency and urgency of passing of stool
 Check for any hyperactive bowel sensation
 Culturing of stool can be done to find the potential etiological organism
 Check the hydration status of the patient by assessing the skin turgor or moisture
content of the mucous membrane
 Enquire the patient whether he has any food intolerance which may lead to increased
peristalsis, or any tolerance to dairy products which may cause lactose intolerance which
in turn increases the osmotic pressure and absorbs water into the intestinal lumen.
 Checking of the medical history of the patient, whether he had any past gastrointestinal
problems or undergone any gastrointestinal surgery
Therapeutic interventions
The therapeutic interventions for treating Traveler’s diarrhea are:
 Prescription of anti-diarrheal drugs, which helps in the suppression of the gastrointestinal
motility hence allowing better absorption of fluid
 Supplementation of probiotics, which reduces the gastrointestinal problems by re-
establishing normal flora in the intestine
 Encourage patient to take more bulk fiber in the diet for better fluid absorption from stool
and thickening of the stool; and avoid stimulants such as caffeine or beverage which
may worsen diarrhea by increasing gastrointestinal motility
 Increase fluid intake, which helps to replace the fluid that is lost through diarrhea

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 Encourage the patients to take meals in small amount and consume foods which are
easy to digest.

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References
Cabal, A., García-Castillo, M., Cantón, R., Gortázar, C., Domínguez, L., & Álvarez, J. (2016).
Prevalence of Escherichia coli virulence genes in patients with diarrhea and a
subpopulation of healthy volunteers in Madrid, Spain. Frontiers in microbiology, 7, 641.
Wasey, A., & Salen, P. (2019). Escherichia coli (E coli 0157 H7). In StatPearls [Internet].
StatPearls Publishing.