E' Coli as a human pathogen

1
E. Coli as a human pathogen

• Lamielle, Gael

2
E. Coli overview

• Part of the Natural Flora of gut
• Different Pathogenic forms
• Enterohemoragic E. coli (EHEC)
• Uropathogenic E. coli (UPEC)
• Extraintestinal pathogenic E. coli (ExPEC)

3
Vectors of Contamination

• Foods
• Animal products (beef, raw milk, )
• Also present in vegetable

4
E. coli in vegetables

• Documented in apple juice, cabbage, lettuce,
  leafy vegetable, growing in soil
• Can survive for more than 6 months in soil
  through Winter-Fall type of weather
• Presence on surface of vegetable
• Role of contaminated water (rinsing, irrigating)

5
E. coli in vegetables

• Can also be internalized by vegetable
• Shelter bacteria from rinsing
• Low risk bacteria internalized on roots and
  seedlings
• Do not survive long inside plant (nutrients, host
  defenses)

6
Pathogenesis

• EHEC (O157H7)
• Gastrointestinal diseases (diarrhea, HUS)
• Role of Shiga-like toxins (SLT I II)
• Attachment to gut epithelium (initial Vs
  intimate), role of pili
• A/E lesions formation of Pedestal

7
Pathogenesis

• UPEC
• Inflammation of Urinary tract
• Attachment of cells to epithelium
• Disruption of apoptosis regulation (NF-?B) in
  host cell
• Presence of Pathogenicity Islands

8
Pathogenicity

• ExPEC
• Infection outside of gastriontestinal urinary
  tract
• Many different symptoms osteomylitis, sepsis,
  neonatal meningitis,
• Opportunist - targets immuno-compromised
• Neonatal meningitis in new-born, crossing
  Blood-Brain Barrier, mental retardation, death
• Streptococcus group B

9
Treatment

• No effective vaccine (non-specific)
• Detection Immunological tests, culture on
  selective media (low ID)
• Antibiotics cephalosporins, ampicillin,
  chloramphinecol
• Resistance amoxillin, cephalothin, tetracyclin
• Antibodies to SLT reduce attachment
• Natural ways yogurt (promote natural flora),
  plant metabolites (esculin)

10
Conclusion

• Many types of infections
• Constant role of pili (maybe present in neonatal
  meningitis)
• Difficult to study pathogenesis human pathogen,
  overgrow in artificial cultures