17.1 CASE STUDY

A 25-year-old, previously healthy woman came to the emergency room for the evaluation of bloody diarrhea and diffuse abdominal pain of 24 hours' duration. She complained of nausea and had vomited twice. She reported no history of inflammatory bowel disease, previous diarrhea, or contact with other people with diarrhea. The symptoms began 24 hours after she had eaten an undercooked hamburger at a local fast food restaurant. Rectal examination revealed watery stool with gross blood. Sigmoidoscopy showed diffuse mucosal erythema and petechiae with a modest exudation but no ulceration or pseudomembranes.

Name four genera of Enterobacterales (previously Enterobacteriaceae) that can cause gastrointestinal disease. Name two genera that can cause hemorrhagic colitis.

The Enterobacterales (formerly known as Enterobacteriaceae) is a large family of Gram-negative bacteria. Several members of this family are well-known pathogens that can cause gastrointestinal diseases.

Gastrointestinal disease + Hemorrhagic colitis 

Genera of Enterobacterales that can cause gastrointestinal disease:

Escherica + Salmonella+ Shigella + Yersinia 

  • Escherichia: Specifically, E. coli is a common member of the gut flora but can also be a pathogen, especially certain strains like Enterohemorrhagic E. coli (EHEC) and Enterotoxigenic E. coli (ETEC).

  • Salmonella: This genus contains two species, S. bongori and S. enterica. The latter is responsible for diseases ranging from mild gastroenteritis to more severe diseases such as typhoid fever.

  • Shigella: These bacteria are known to cause shigellosis or bacillary dysentery, characterized by bloody diarrhea.

  • Yersinia: While Y. pestis is the causative agent of plague, Y. enterocolitica and Y. pseudotuberculosis can lead to gastrointestinal diseases.

Genera that can cause hemorrhagic colitis:

Escherichia+ Shigella 

  • Escherichia: Specifically, certain strains of E. coli, like the O157:H7 strain, can cause hemorrhagic colitis.

  • Shigella: Some strains of Shigella can cause bloody diarrhea, but it's essential to note that the classic hemorrhagic colitis, particularly associated with undercooked beef, is more commonly linked to the E. coli O157:H7 strain.


Given the case's description of the consumption of undercooked hamburger meat and the subsequent bloody diarrhea, Enterohemorrhagic E. coli (EHEC) or E. coli O157:H7 would be a prime suspect.


Mind Map: Enterobacterales and Gastrointestinal Diseases

Central Idea: Enterobacterales can cause gastrointestinal diseases, including hemorrhagic colitis.

Main Branches:

  1. Genera of Enterobacterales that can cause gastrointestinal disease

  2. Genera that can cause hemorrhagic colitis

1. Genera of Enterobacterales that can cause gastrointestinal disease:

  • Escherichia

    • E. coli

    • E. coli is a common member of the gut flora but can also be a pathogen. Especially:

      • Enterohemorrhagic E. coli (EHEC)

      • Enterotoxigenic E. coli (ETEC)

  • Salmonella

    • diseases ranging from mild gastroenteritis to more severe diseases such as typhoid fever.

      • S. bongori

      • S. enterica

  • Shigella

    • cause shigellosis or bacillary dysentery, characterized by bloody diarrhea.

  • Yersinia

    • Y. enterocolitica

    • Y. pseudotuberculosis

2. Genera that can cause hemorrhagic colitis:

  • Escherichia

    • E. coli

      • O157:H7 strain cause hemorrhagic colitis

  • Shigella

    • some strains, but it is more associated with E.coli

Note: The case description suggests Enterohemorrhagic E. coli (EHEC) or E. coli O157:H7 as a possible cause of the patient's symptoms due to the consumption of undercooked hamburger meat.