What is the bacteria that causes traveler's diarrhea?

Bacteria Causing Traveler's Diarrhea

Enterotoxigenic Escherichia coli (ETEC) is the most common bacterial cause of traveler's diarrhea, followed by enteroaggregative E. coli (EAEC), Campylobacter, Shigella, and Salmonella species. 1, 2

Primary Bacterial Pathogens

Traveler's diarrhea is predominantly caused by bacterial pathogens, which account for 80-90% of cases 2. The major bacterial causes include:

1. Escherichia coli pathotypes:

   • Enterotoxigenic E. coli (ETEC) - The predominant cause globally
   • Enteroaggregative E. coli (EAEC) - Increasingly recognized as a major pathogen
   • Other pathogenic E. coli strains

2. Other important bacterial pathogens:

   • Campylobacter species - Particularly common in Southeast Asia
   • Shigella species - Often causes dysentery
   • Non-typhoidal Salmonella species

Regional Variations

The prevalence of specific pathogens varies by geographic region:

• Southeast Asia: Higher rates of fluoroquinolone-resistant Campylobacter
• India: Higher rates of fluoroquinolone-resistant ETEC compared to Central America 2
• Cruise ships/resorts: Increased likelihood of viral causes (norovirus, rotavirus)

Clinical Presentation

The clinical presentation depends on the causative pathogen:

• ETEC/EAEC: Typically causes watery diarrhea without blood
• Campylobacter/Shigella: More likely to cause bloody diarrhea (dysentery)
• Fever: Present in up to 30% of traveler's diarrhea cases 2

Diagnostic Considerations

Diagnosis is typically clinical, but specific testing may include:

• Stool culture with specific testing for pathogenic E. coli
• Molecular techniques to identify virulence genes
• Toxin detection assays for certain pathotypes 1

Treatment Implications

Understanding the causative organism has important treatment implications:

• ETEC infections: Respond well to rifaximin, which is FDA-approved for traveler's diarrhea caused by noninvasive E. coli strains 3
• Campylobacter: Increasing resistance to fluoroquinolones, particularly in Asia; azithromycin may be preferred 2, 4
• Shigella/Salmonella: The effectiveness of rifaximin has not been proven 3

Pitfalls and Caveats

1. Antibiotic resistance: Increasing resistance to fluoroquinolones and other antibiotics among all major pathogens causing traveler's diarrhea 2

2. Mixed infections: Co-infections with multiple pathogens are common and may complicate treatment 2

3. Non-bacterial causes: While bacteria predominate, viruses and parasites can also cause traveler's diarrhea and may require different management approaches

4. Empiric treatment limitations: Rifaximin should not be used when fever or bloody diarrhea is present, as these suggest invasive pathogens like Campylobacter, Shigella, or Salmonella 3

Understanding the specific bacterial cause of traveler's diarrhea is essential for appropriate treatment selection and to address the growing challenge of antimicrobial resistance among these pathogens.