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Schenectady County Community College

Escherichia coli

Gram stain:  negative
Cell shape:  bacillus
Arrangement:  single
Oxygen requirements:  facultative anaerobe
Optimum temperature:  37 °C
Motility:  variable
Other:  typically lactose fermenting; produces characteristic green metallic sheen on EMB (eosin methylene blue) agar.

Habitat:  human intestinal tract; almost universal member of normal flora in humans and a number of animals.

Diagnosis:  culture of feces, serologic identification

Pathogenicity:  normally not pathogenic; a few virulent strains cause of bladder infections, diarrhea. Generation time = 24 hours.

Four types of E. coli are usually associated with diarrhea:
  • enterotoxigenic - (ETEC) cause of traveller's diarrhea and diarrhea in infants
  • enteroinvasive - (EIEC) disease much like that caused by Shigella spp.
  • enteropathogenic - (EPEC) diarrhea in nurseries; chronic children's diarrhea
  • enterohemorrhagic - (serological type O157:H7) hemolytic-uremic syndrome

Transmission:  fecal-oral route

Treatment:  gentamicin or polymyxin (for infants); tetracycline; bismuth preparations (Pepto-Bismol); replacement of lost fluids


CDC: Escherichia coli O157:H7
Escherichia coli
The Family Enterobacteriaceae - General Overview
FDA/CFSAN Bad Bug Book - Escherichia coli O157:H7
FDA/CFSAN Bad Bug Book - Enteronvasive E. coli
FDA/CFSAN Bad Bug Book - Enteropathogenic E. coli
FDA/CFSAN Bad Bug Book - Enterotoxigenic E. coli
Urine smear Escherichia coli/PMN
Spices May Reduce E. coli O157:H7 In Meat