Enterobacteriaceae - Escherichia coli

Colon bacillus

Common name of Escherichia coli

Large intestine

Where do E. coli commonly resides?

diarrheagenic strains of Escherichia coli

Despite that E. coli resides in large intestine, it still causes diarrhea. What is it specifically called?

Enteropathogenic E. coli (EPEC)

- It causes the loss of microvilli; there is no toxin production

- Attached to the brush border of the intestinal epithelial cells, causing cellular damage (with adhesive property)

Infantile diarrhea (stool without blood)

disease caused by Enteropathogenic E. coli

Pathogenicity Islands

Virulence factor of Enteropathogenic E. coli

O55:NM

O55:H6

O111:NM

O111:H2

Serotypes of Enteropathogenic E. coli

HeLa cell assay

Lab test of Enteropathogenic E. coli

(+) H antigen and intimin

Classification of Enteropathogenic E. coli

Enterotoxigenic E. coli (ETEC)

- Colonization occurs in the proximal small intestine

- Infectious dose: 10^6 to 10^10

Traveler’s diarrhea

Disease caused by Enterotoxigenic E. coli (ETEC)

Heat stable and heat labile enterotoxins

Virulence factor of Enterotoxigenic E. coli (ETEC)

O6:NM

O8:H9

Serotypes of Enterotoxigenic E. coli (ETEC)

Persons with achylorhydria are at high risk

Characteristics of Enterotoxigenic E. coli (ETEC)

Enteroinvasive E. coli (EIEC)

- It penetrates and multiplies within the intestinal epithelial cells.

- Infective dose: 10

Dysentery-like or Shigella-like infection

Watery diarrhea with WBC

Disease caused by Enteroinvasive E. coli (EIEC)

Invasin

Virulence factor of Enteroinvasive E. coli (EIEC)

O124:H30

O143:NM

Serotypes of Enteroinvasive E. coli (EIEC)

Atrichous, LF/NLF

(+) large plasmid

(+) Serenity test

Characteristics of Enteroinvasive E. coli (EIEC)

Enterohemorrhagic E. coli (EHEC)

- The toxins produced by this strain destroy vascular endothelial cells.

Hemorrhagic colitis

Hemolytic uremic syndrome (HUS)

Bloody diarrhea without WBCs

Diseases caused by Enterohemorrhagic E. coli (EHEC)

Verotoxin 1 and 2 or Shigalike toxin

Virulence factor of Enterohemorrhagic E. coli (EHEC)

O157:H7

O157:NM

Serotype of Enterohemorrhagic E. coli (EHEC)

(+) Intimin

(-) MUG

Associated with thrombotic thrombocytopenic purpura

Characteristics of Enterohemorrhagic E. coli (EHEC)

Enteroaggregative E. coli (EAEC)

- EAEC adheres to the surface of the Intestinal mucosa

Persistent watery diarrhea (EAEC)

Disease caused by Enteroaggregative E. coli (EAEC)

Diffusely adherent E. coli (DAEC)

- DAEC adheres to Hep-2 cells which form clumps of bacteria

Pediatric diarrhea and UTI (DAEC)

Disease caused by Diffusely adherent E. coli (DAEC)

Fimbriae

Virulence factor of Enteroaggregative E. coli (EAEC) and Diffusely adherent E. coli (DAEC)

O44:H18

Serotype of Enteroaggregative E. coli (EAEC) and Diffusely adherent E. coli (DAEC)

EAEC has a “stacked-brick” appearance

Lab test: HeLa cell assay

Characteristics of Enteroaggregative E. coli (EAEC) and Diffusely adherent E. coli (DAEC)

Uropathogenic E. coli (UPEC)

Most common cause of UTI in humans

UTI

Disease caused by Uropathogenic E. coli (UPEC)

Common pili

Aerobactins

cytolysins

Virulence factor of Uropathogenic E. coli (UPEC)

Type I fimbriae adheres strongly to the urinary tract

Characteristics of Uropathogenic E. coli (UPEC)