What type of diarrhea is characteristic of bacterial gastroenteritis?

Types of Diarrhea in Bacterial Gastroenteritis

Bacterial gastroenteritis typically presents with acute inflammatory diarrhea characterized by bloody and/or mucoid stools, often accompanied by fever, abdominal pain, and tenesmus. 1

Clinical Presentations of Bacterial Diarrhea

Bacterial gastroenteritis can manifest with two distinct clinical patterns:

1. Inflammatory Diarrhea (Most Common)

   • Characterized by:
     • Bloody and/or mucoid stools
     • Presence of fecal leukocytes
     • Fever
     • Abdominal pain
     • Tenesmus (painful straining)
   • Common pathogens:
     • Shigella
     • Salmonella
     • Campylobacter
     • Enterohemorrhagic E. coli (STEC)
     • Yersinia
     • Vibrio species

2. Watery Diarrhea

   • Less commonly seen with bacterial pathogens
   • May be voluminous (especially with cholera)
   • Often caused by enterotoxin-producing bacteria
   • Common pathogens:
     • Enterotoxigenic E. coli
     • Vibrio cholerae (rice-water stools)
     • Clostridium perfringens

Specific Clinical Patterns by Pathogen

The 2017 IDSA guidelines 1 identify several distinct clinical presentations that can help differentiate bacterial causes:

Clinical Presentation	Common Bacterial Pathogens
Visible blood in stool	STEC, Shigella, Salmonella, Campylobacter, Vibrio (non-cholera), Yersinia
Severe abdominal pain with bloody stools and minimal/no fever	STEC, Salmonella, Shigella, Campylobacter, Yersinia
Persistent abdominal pain and fever	Yersinia enterocolitica, Yersinia pseudotuberculosis (may mimic appendicitis)
Diarrhea and abdominal cramping (1-2 days)	Clostridium perfringens, Bacillus cereus
Large volume rice-water stools	Vibrio species

Pathophysiological Mechanisms

Bacterial diarrhea occurs through several mechanisms 1, 2:

1. Mucosal invasion - Pathogens like Shigella, Salmonella, and Campylobacter invade the intestinal mucosa, causing inflammation, ulceration, and bloody diarrhea

2. Toxin production - Bacteria like STEC produce toxins that damage the intestinal mucosa, leading to hemorrhagic colitis

3. Enteroadherence - Some pathogens adhere closely to mucosal epithelial cells, disrupting normal function

4. Cytotoxin production - Certain bacteria produce cytotoxins that directly damage intestinal cells

Diagnostic Considerations

When evaluating patients with suspected bacterial gastroenteritis:

• Stool characteristics (bloody, mucoid, watery) are key diagnostic indicators
• Presence of fecal leukocytes suggests inflammatory bacterial diarrhea
• Fever is generally higher with bacterial than viral causes
• Severe abdominal pain with bloody diarrhea strongly suggests bacterial etiology

Clinical Pitfalls and Caveats

• Not all bacterial gastroenteritis presents with bloody diarrhea - toxin-mediated cases may be watery
• STEC infection often presents without fever despite bloody diarrhea
• Multiple pathogens may be detected simultaneously with modern multiplex testing
• Antibiotic treatment is not always indicated and may worsen certain infections (like STEC)
• Inflammatory diarrhea can mimic inflammatory bowel disease, requiring careful differentiation

The presence of inflammatory diarrhea with blood, mucus, and leukocytes is the hallmark of bacterial gastroenteritis, distinguishing it from most viral and parasitic causes which typically produce watery, non-inflammatory diarrhea.