E.coli is a gram negative, rod shaped, facultative anaerobic bacterium found in the intestine of warm blooded animals. Mostly they are harmless but some strains are pathogenic cause diseases.

1. Escherichia coli
Prepared By:
Mehak Saeed
MSc. Biotechnology
University Of Karachi

2. INTRODUCTION
E.coli:
E.coli are bacteria found in the environment, foods, and
intestines of people and animals. They are spread due to fecal
contamination.

3. DISCOVERY
➢E.coli bacteria were discovered in the human colon in 1885 by German
bacteriologist Theodor Escherich.
➢Although E.coli bacteria were initially called Bacterium coli, the name was later
changed to Escherichia coli to honor its discoverer.

4. MORPHOLOGY
➢Gram Negative
➢Rod Shaped
➢Facultative Anaerobe
➢Non-Sporulating
➢Motile
➢Coliform
➢2-10μ Long
➢0.25-1.0μ in Diameter
E.coli

5. METABOLISM
Produce:
➢Lactate
➢Succinate
➢Ethanol
➢Acetate
➢Carbon dioxide

6. CULTURE GROWTH
➢Optimum growth at 37C (98.6F)
➢In Lab, grow at 49C (120F)
➢Grow in any lab media which contain Glucose, Lactose, NaCl, Ammonium
phosphate, monobasic potassium phosphate, and Water.

7. GROWTH RESULTS ON MEDIA
E.coli on MacConkey Agar E.coli on EMB Agar

8. BIOCHEMICAL REACTIONS
➢Ferment glucose, Lactose, Mannitol, and maltose and produce Acid and Gas.
➢Sucrose is not fermented by typical strains of E.coli.
➢In Triple Sugar Iron Agar, E.coli produce Acid and Gas.
➢IMVIC Test used to identify members of Enterobacteriaceae.
➢E.coli is:
▪Indole positive Vogues P (VP) negative
▪Methyl red (MP) positive Citrate negative
➢No H2S gas production.
➢No hydrolysis of Urea.

9. ANTIGENIC STRUCTURE
E.coli has three antigens:
➢O (Somatic) antigen
➢H- (Flagellar) antigen
➢K- (Kapsular) antigen

10. MEDICAL IMPORTANCE OF E.coli
➢Used to produce insulin by adopting genetic engineering techniques.
➢Produce certain vitamins in the intestine.
➢Used as parameter to determine the fecal contamination of water.
➢Used for the study of plasmids in the bacterial genetics.

11. TOXINS OF E.coli
Some strains of E.coli are highly pathogenic and can cause diseases. Besides the
endotoxin associated with O antigen, these strains produce two types of
exotoxin.
➢Enterotoxin
➢Haemolysin

12. CATEGORIES OF E.coli
Pathogenic E.coli can be divided into several categories according to its serological
characteristics and virulence properties, mainly consisting of:
➢Enterohemorrhagic E.coli
➢Enteropathogenic E.coli
➢Enteroaggregative E.coli
➢Enteroinvasive E.coli
The most famous member of Enterohemorrhagic E.coli is the strain 0157:H7 that can
cause bloody diarrhea and fever.

13. CLINICAL INFECTIONS CAUSED BY E.coli
Virulent strains of E.coli are mainly responsible for three types of infections
in humans:
➢Urinary tract infections
➢Neonatal meningitis
➢Intestinal diseases

14. COMMON SIGNS AND SYMPTOMS
Signs and symptoms include:
➢Severe abdominal cramps, pain or tenderness
➢Diarrhea, which may range from mild and watery to severe and bloody
➢Nausea and vomiting, in some people
➢Fever

15. SOURCES OF EXPOSURE TO E.coli
Potential sources of exposure include:
➢Contaminated Food
➢Contaminated Water
➢Person to person contact

16. PREVENTION
Avoid risky foods:
▪ Meat should be well-done, with no pink color showing anywhere in the meat.
▪Drink pasteurized milk, juice and cider.
▪Wash raw produce thoroughly.
Avoid cross-contamination:
▪Wash utensils
▪Keep raw foods separate
▪Wash hands

17. CONCLUSION
➢Escherichia coli is a type of bacteria of the genus Escherichia that is commonly
found in the lower intestine of warm-blooded organisms.It is also found in the
gut of some animals.
➢ Most types of E. coli are harmless and even help keep the digestive tract
healthy. But some strains can cause diarrhea if a person eat contaminated food or
drink fouled water.

18. Thank You