Family Enterobacterales. Escherichia coli

• What type of bacteria is Family Enterobacteriaceae?

  Gram -ve Bacilli
• Are Enterobacteriaceae motile or non-motile?

  Motile
• Do Enterobacteriaceae form spores?

  Non-spore forming
• What are the major antigens of Enterobacteriaceae?

  H, K, and O antigens
• What do H antigens represent in Enterobacteriaceae?

  Flagellar antigens
• What do K antigens represent in Enterobacteriaceae?

  Capsular antigens
• What do O antigens represent in Enterobacteriaceae?

  Somatic antigens
• What is the role of endotoxins in Enterobacteriaceae?

  Induce immune response and hemorrhage
• What is a characteristic of the polysaccharide core of endotoxins?

  Highly variable
• How many oligosaccharide monomers can the antigen O have?

  1-20
• What is a feature of the exotoxins produced by Enterobacteriaceae?

  Excreted thermosensitive proteins
• What do adhesion factors like fimbriae do?

  Help bacteria adhere to surfaces
• What is the morphology of Escherichia coli?

  Gram -ve, rod-shaped
• Is Escherichia coli oxidase positive or negative?

  Oxidase -ve
• What is the indole test result for Escherichia coli?

  Indole +ve
• What is the H2S and citrate test result for Escherichia coli?

  H2S & Citrate +ve
• What type of colonies does Escherichia coli produce on MacConkey Agar?

  Pink colonies
• What is the significance of beta-galactosidase in Escherichia coli?

  Cleaves lactose into galactose and glucose
• What is the role of lipopolysaccharide (LPS) toxin in Escherichia coli?

  Induces release of IL-1, IL-6, TNF-alpha
• What can the presence of K-antigen in Escherichia coli lead to?

  Neonatal meningitis
• What are the pathogenic strains of E. coli?

  • Enterotoxin E. coli (ETEC)
  • Enteropathogenic E. coli (EPEC)
  • Enteroinvasive E. coli (EIEC)
  • Enterohaemorrhagic E. coli (EHEC)
• What specimens are used for microbiological diagnosis of E. coli?

  Faeces, urine, blood, CSF
• What is the differential media used for E. coli culture?

  MacConkey Agar and Eosin-Methylene Blue Agar
• What color do E. coli colonies appear on Eosin-Methylene Blue Agar?

  Metallic Green
• What does the indole test for E. coli indicate?

  Presence of tryptophanase enzyme
• What is the reservoir for Enterotoxin E. coli (ETEC)?

  Contaminated food and water
• How is Enterotoxin E. coli (ETEC) transmitted?

  Faecal-oral route
• What is the virulence factor of Heat-Labile Enterotoxin in ETEC?

  Overactivates adenylate cyclase
• What are the clinical manifestations of ETEC infection?

  Traveller’s diarrhoea and gastroenteritis
• What is the treatment for ETEC infection?

  Self-limiting, antibiotics like ciprofloxacin
• What is the reservoir for Enteropathogenic E. coli (EPEC)?

  Natural gut flora
• How is Enteropathogenic E. coli (EPEC) transmitted?

  Ingestion of contaminated food and water
• What are the virulence factors of EPEC?

  Adherence to intestinal epithelium and inflammatory response
• What are the clinical manifestations of EPEC infection?

  Gastroenteritis, usually in children
• What is the treatment for EPEC infection?

  Ciprofloxacin and cotrimoxazole
• What is the reservoir for Enteroinvasive E. coli (EIEC)?

  Natural gut flora
• How is Enteroinvasive E. coli (EIEC) transmitted?

  Ingestion of contaminated food and water
• What are the virulence factors of EIEC?

  Direct invasion of intestinal epithelium and enterotoxin formation
• What are the clinical manifestations of EIEC infection?

  Diarrhoea and gastroenteritis
• What is the treatment for EIEC infection?

  Ciprofloxacin and cotrimoxazole