Escherichia coli is a Gram-negative, facultative anaerobic and non-sporulating bacteria that grows optimally at 37°C. It possesses flagella that allow it to swim and is motile. E. coli has four types of antigens and several virulence factors that allow some strains to cause diseases like gastroenteritis, urinary tract infections, and neonatal meningitis. It is normally found in the gastrointestinal tract of humans and animals, where it plays an important role. While some pathogenic strains cause disease, nonpathogenic strains like E. coli Nissle 1917 are used as probiotics. E. coli is also widely used in biotechnology research due to its well-known genetics.

1. Escherichia coli

2. Escherichia coli
• Gram-negative.
• facultative anaerobic.
• non-sporulating.
• Optimal growth of
Escherichia coli
occurs at 37°C.

3. • Strains that possess flagella can swim and are
motile .

4. Antigenic structure
• E. coli possess 4 types of antigens :
H (flageller) antigen
O (somatic) antigen
K (capsular) antigen
F (fimbrial) antigen

5. Virulence factors of E. coli
Enterotoxin
Haemolysin
Verotoxin
Adhesin
Capsules

6. Role in disease
 Virulent strains of E. coli can cause :
• Gastroenteritis.
• urinary tract infections.
• neonatal meningitis.

7. Laboratory diagnosis
• Specimens collected according to the site of infection:
pus
Stool
CSF
Urine
Specimen inoculated on special media, then colonies
identified.

8. EMB
Blood agar
MacConkey agar

9. • Biochemical tests
API TEST

10. •Antimicrobial sensitivity tests

11. Treatment of E. coli infections
• Antibiotics which may be used to treat E. coli infection
include:
amoxicillin.
cephalosporins.
ciprofloxacin.

12. Role as normal microbiota
E. coli normally colonizes an infant's gastrointestinal tract within 40
hours of birth, arriving with food or water or with the individuals
handling the child. In the bowel, it adheres to the mucus of the large
intestine. It is the primary facultative anaerobe of the human
gastrointestinal tract .

13. Therapeutic use of nonpathogenic E. coli
Nonpathogenic E. coli strain Nissle 1917 is used as a probiotic
agent in medicine, mainly for the treatment of various
gastroenterological diseases.

14. E. coli possess the ability to transfer DNA
via bacterial :
which allows genetic material to spread horizontally
through an existing population.
Conjugation
Transduction
Transformation

15. • So new strains of E. coli evolve through horizontal
gene transfer.

16. The first complete DNA sequence of an E. coli genome was
published in 1997. It was found to be a circular DNA molecule with
4.6 million base pairs in length, containing 4288 protein-coding
genes.
Role of E. coli in biotechnology researches

17. • As the genetic structure of E. coli was well known, and it is an
organism which can grow on simple media (mineral salts and
glucose) under aerobic and anaerobic conditions, the bacterium
became the basis for most developments in biotechnology
researches.
• An example of the use of E. coli in biotechnology in order to produce
a useful product is illustrated by the use of the E. coli plasmid to
clone the gene for production of the human growth hormone and
insulin hormone.