Escherichia coli

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Gram stain Culture

General information
- Taxonomy
  Family: Enterobacteriaceae, genus: Escherichia coli
  E. albertii, E. fergusonii, E. hermannii, E. vulneris
  
  Natural habitats
  Widely distributed in nature, water, soil, foods and clinical samples.
  
  The genus Escherichia will occupy the last part of the small intestine and the large intestine in humans and warm-blooded animals. In more than 99% of the isolates, it is a Escherichia coli.
  
  E. coli is a good indicator of the water it is clean. (fecal contamination)
  
  Clinical significance
  They are generally located in the intestinal lumen (colon), but some strains can cause a variety of infections, enteritis, septicemia, peritonitis, urinary infections, meningitis (neonatal) etc, in humans and animals.
Diseases
- Meningitis
Gram stain
- Gram negative rods,
  
  1-3 x 0.5 µm, though their size can be impacted by temperature, growth state, and exposure to antibiotics.
  
  They occur singly or in pairs
Culture characteristics
- Facultative anaerobic
  
  BA: colonies appear round, smooth (S-type), low convex, moist and gray with a shiny surface, entire edge. R-type or mucoid forms may occur.
  
  Some strains may demonstrate a narrow zone of β-hemolysis.
  
  McConkey:
  lactose fermenter: colonies are flat, dry and pink
  non lactose fermenter: colonies are pale (5%)
  
  BBAØ: growth
Characteristics
References
- James Versalovic et al.(2011) Manual of Clinical Microbiology 10th Edition