22. Infectious Diarrhea

For Clostridioides difficile, see GI: Diarrhea in Hospitalized Patients

Overview

  • Most cases are self-limited bacterial or viral infections and will resolve <3 days in immunocompetent-hosts.
  • Further evaluation is warranted for profuse diarrhea with dehydration, fever, bloody diarrhea, severe abdominal pain, recent antibiotic use, and patients who are elderly or immunocompromised.

Etiology / Risk Factors

Determine how illness started, duration, frequency and quality of stools (bloody/watery), signs and symptoms of hypovolemia, travel history, exposure history (see below), sick contacts, new medications (or recent antibiotics), and other associated symptoms (fever, etc.).

Bacteria

Viruses

Aeromonas hydrophila

CMV (HIV, transplant recipients)

*Bacillus cereus (beef, pork, fried rice), incubation 1-6 hours

Norovirus (cruises, institutional outbreaks)

Campylobacter (undercooked poultry, raw dairy)

Rotavirus (daycares)

Clostridioides difficile

Protozoa

Enterohemorrhagic E. coli, aka EHEC (beef esp. undercooked hamburger, pork, dairy, apple cider)

Cryptosporidium (daycares, swimming pools, HIV, cows)

Enteroinvasive E. coli (dairy)

Cyclospora (raspberries)

Enterotoxigenic E. coli (travelers)

Entamoeba histolytica (Mexico, MSM)

Mycobacterium avium complex

Giardia (daycare, swimming pools, mountain streams)

Salmonella (beef, pork, poultry, raw dairy, lizard exposure, travel)

Isospora (HIV)

Shigella (daycares, vegetables, homeless, HIV)

Microsporidium (HIV)

*Staph aureus (salads, meat, dairy), incubation 1-6 hours

 

Vibrio cholera

 

Vibrio parahaemolyticus (raw seafood, cirrhosis)

 

Yersinia (beef, milk, cheese, iron overload states)

Note: Blastocystis hominis (usually not a pathogen unless in the very immunosuppressed)

*toxin mediated food poisoning

  • Bloody diarrhea with fever (dysentery) is suggestive of bacterial pathogens (Enterohemorrhagic E. coli, non-typhoidal Salmonella, Shigella, Campylobacter) or amoebic colitis.

Acute Diarrhea in Resource Rich Settings

Watery Diarrhea

Inflammatory Diarrhea

(fever, mucoid or bloody stools)

Norovirus

Nontyphoidal Salmonella

Clostridium perfringrens

Campylobacter spp

ETEC

Shigella spp

Other enteric viruses (rotavirus, adenovirus, astrovirus, sapovirus)

EHEC

Giardia lamblia

Yersinia spp

Cryptosporidium parvum

Vibrio parahemolyticus

Listeria monocytogenese

Entamoeba histolytica

Cyclospora cayetanensis

 

Evaluation

  • Traveler’s or community acquired diarrhea: if fevers or bloody stool, send stool gram stain and cultures for Salmonella, Shigella, Campylobacter. Diagnostic yield 1.5-5.6% for all patients, but higher in severe illness. Negligible yield if hospitalized > 3 days unless immunocompromised.
    • At the VA and Moffitt, can send a stool PCR for common pathogens
    • E coli O157:H7 culture and toxin assay: call lab if bloody or +risk factors (automatically done as part of the stool culture at UCSF - Moffitt).
    • Rule out C diff if previous antibiotics, healthcare exposure or immunocompromised (note, rarely causes bloody diarrhea). 
  • Persistent diarrhea (>7 days): consider Giardia (stool antigen), acid-fast stains for Cryptosporidium, Cyclospora and Isospora. O&P x 3.
    • If HIV+ add microsporidium assay and consider MAC (need colonoscopy for biopsy).
    • Persistent abdominal pain and fever: culture for Yersinia entercolitica.
    • Seafood exposure: culture for Vibrio spp.
  • Consider sigmoidoscopy for proctitis in MSM or HIV (HSV, GC, Chlamydia, syphilis, Giardia, in addition to usual pathogens) with biopsy to rule out CMV.
  • Fecal leukocytes (sensitivity 70%) can help document inflammation from invasive Salmonella, Shigella, Campylobacter, IBD, severe C diff.
  • Fecal lactoferrin – has 90-100% sensitivity and specificity in distinguishing between inflammatory (bacterial + IBD) vs. non-inflammatory (viral, protozoal).

Management

(note that dosing is for immunocompetent hosts)

  • Supportive care is the mainstay of treatment: IV Fluids and electrolyte repletion. Diet: bland, low fat, with limited dairy.
  • Empiric antibiotics are not recommended in watery diarrhea.
  • In inflammatory diarrhea in immunocompetent patients, empiric antibiotics are generally not recommended while waiting for diagnostic studies to return.
    • Typical empiric regimen is fluoroquinolone or macrolide depending on local antibiogram and travel history.
    • Avoid empiric antibiotics if EHEC is suspected given concern that antibiotics can lead to increased Shiga toxin production
  • Giardia: metronidazole 250-500mg TID x 7-10 days.
  • Isospora and Cyclospora: TMP-SMX DS BID x 7-10 days.
  • Antimotility agents: contraindicated in bloody diarrhea with fever and with C. difficile. If just diarrhea, can start loperamide 4mg once, then 2mg after each unformed stool, not to exceed 16mg.
  • Probiotics: may improve traveler’s diarrhea, but efficacy remains unclear. They may improve secondary lactase deficiency, a common sequela of diarrhea.
  • Potential complications: HUS in enterohemorrhagic E. coli, Guillain-Barre in C. jejuni, malnutrition, and dehydration. 

Key Points

  • Most cases of infectious diarrhea are self-limited bacterial or viral infections.
  • Dysentery suggests a bacterial infection or amoebic colitis.

IDSA Practice Guidelines for Acute Infectious Diarrhea:

https://www.idsociety.org/practice-guideline/infectious-diarrhea/

Barr W, Smith A. Acute diarrhea. Am Fam Physician. 2014;89(3):180‐189.

AU Guerrant RL, Van Gilder T, et al. Infectious Diseases Society of America, Practice guidelines for the management of infectious diarrhea. Clin Infect Dis. 2001;32(3):331.

Guerrant, RL et al. "Practice Guidelines for the Management of Infectious Diarrhea" Clinical Infectious Diseases 2001; 32:331–50

Mandell GL, Bennett JE, Dolin R. Principles and Practice of Infectious Diseases, Sixth Edition. Churchill Livingstone;2005.

Key words: Diarrhea, Travel, E coli