Diarrhea is a change in normal bowel movements characterized by increase in frequency, water content or volume of stools. The usual stool output is 10 g/kg/day.
Acute diarrhea lasts ≤14 days while chronic diarrhea lasts >14 days.
Infectious diarrhea is usually associated with symptoms of nausea and vomiting and abdominal cramps.

Principles of Therapy

Traveler's Diarrhea

  • The objectives of antimicrobial treatment of traveler’s diarrhea are shortening illness & returning travelers to normal activities
  • Eradication of enteropathogens from stool does not predict the clinical benefits of antimicrobial therapy
  • Traveler’s diarrhea is typically short-lived & self-limited, but many organisms that cause the infection can be treated with antibiotics
  • Choice of therapy should depend on epidemiologic data


  • Rehydration is the mainstay of therapy
  • When antibiotics are administered to cholera patients, there is reduction of stool volume loss & a shorter clinical course
  • Antibiotics administered should follow recent sensitivity data for V cholera, if available

Bloody Diarrhea

  • Antipropulsives should be avoided as these drugs may increase the severity by delaying excretion of organisms & facilitating invasion of the mucosa

Empiric Antibiotic Therapy

Traveler's Diarrhea

Empiric treatment of traveler’s diarrhea has been the best approach, but its usefulness is being undermined by growing antibiotic resistance in many parts of the world


  • May be the treatment of choice for C jejuni infection for patients 2-8 years of age
  • Reported effective against traveler’s diarrhea in Southeast Asia
Co-trimoxazole [Sulfamethoxazole (SMZ) & Trimethoprim (TM)]
  • Historically the drug of choice for treatment of traveler’s diarrhea
  • Resistance of enterotoxigenic E coli (ETEC) & Salmonella sp to this drug limits its usefulness
  • Doxycycline & Tetracyclines are preferred agents against V cholera
    • Not recommended in patients <8 years of age
  • Co-trimoxazole, Erythromycin & Ciprofloxacin are alternative drugs
Bloody Diarrhea
  • Antibiotics may reduce the duration of illness & shorten the carrier stage
  • Initiation of empiric antibiotics may be considered in special situations:
    • Infants <3 months old with manifestations of bacterial infection
    • Immunocompetent patients exhibiting signs & symptoms of Shigella infection (fever, abdominal pain,hematochezia)
    • Recently traveled & with fever of ≥38.5°C & other signs of septicemia
  • Once enterohemorrhagic Escherichia coli (EHEC) or Shiga toxin-producing E coli (STEC) has been excluded by stool exam, empiric therapy with antibiotics can be started
  • Broad-spectrum antimicrobials should be started in patients with signs & symptoms pointing to sepsis as soon as specimens have been collected
    • Antibiotic therapy should be tailored once results become available 
  • Antibiotics following the local sensitivities for Shigella sp may be used as empiric therapy before waiting for culture & sensitivity results
  • Ciprofloxacin or any 3rd generation cephalosporin (eg Ceftriaxone, Cefotaxime) may be used as empiric therapy for infants <3 months of age, & patients with central nervous system manifestations, or Azithromycin in pediatric patients, depending on location & antimicrobial susceptibility data, & travel history
  • There is widespread resistance to the following drugs: Ampicillin, Co-trimoxazole, Chloramphenicol, Nalidixic acid, Tetracycline, Gentamicin & 1st- & 2nd-generation cephalosporins
  • There is also reported resistance to Ciprofloxacin in some countries
Adjunctive Therapy
  • Bacillus clausii is an antidiarrheal microorganism that is given for acute or chronic or persistent diarrhea due to infections, drugs or poisons
    •  It contributes to the recovery of the intestinal microbial flora altered during the course of microbial disorders of diverse origin
    • Capable of producing various vitamins, in particular group B vitamins, hence it contributes to correcting the consequent vitamin disorders caused by antibiotics & chemotherapeutic agents in general
    • Makes it possible to obtain a nonspecific antigenic & antitoxic action, closely connected with the metabolic action of Bacillus clausii
  • Probiotics have been shown to reduce the intensity & duration of diarrhea of acute infectious diarrhea in children
    • Example includes Lactobacillus spp, Saccharomyces boulardii, Bifidobacterium spp
  • Zinc supplementation given during an episode of diarrhea may decrease the duration & severity of diarrheal illness
  • Antiemetic agents (eg Ondansetron) may be used in patients >4 years of age to decrease vomiting or help avoid the need for intravenous fluid, but may increase episodes of diarrhea

Pathogen-Specific Treatment of Bacterial Diarrhea

Pathogen Preferred Agent(s) Alternative Agent(s) Remarks
Aeromonas/ Plesiomonas spp Antibiotics not usually required 
Aeromonas sp: Antibiotics may be indicated in patients prone to septicemia (eg cirrhosis, immunocompromised patients)
Plesiomonas sp: Antibiotics may be required in severely ill or immunocompromised patients
Co-trimoxazole Ciprofloxacin1
Campylobacter spp Antibiotics not usually required; may be used in severely ill patients or traveler’s diarrhea
  • A self-limiting condition
  • Early treatment can shorten the duration of the illness & prevent any relapse
Tetracycline or Doxycycline2
EHEC 0157:H7 Antibiotics & antipropulsives are contraindicated; may increase the chance of developing hemolytic uremic syndrome  
Salmonella spp Cefotaxime
  • Ceftriaxone may be considered in suspected septicemic cases
  • Follow available local epidemiologic data
Shigella spp Cefotaxime
  • A self-limiting condition
Yersinia spp Co-trimoxazole
Tetracycline or Doxycycline2
Antipseudomonal aminoglycosides
3rd generation cephalosporins (eg Cefotaxime)
1Ciprofloxacin is not recommended in patients <18 years of age, except in cases when potential benefits outweigh the risks.
2Tetracycline & Doxycycline are contraindicated in patients <8 years of age.

Non-Pharmacological Therapy

Dietary Therapy

  • Depends on age & diet history
  • Breastfed patients should continue nursing on demand while formula-fed patients must continue their usual full-strength milk
    • Based on several trials, feedings with diluted formula is associated with protracted symptoms & delayed nutritional recovery
  • Lactose-free formulas are recommended in patients with documented & persistent lactose intolerance
  • Intake of patient’s usual diet is recommended
  • Foods high in simple sugars should be avoided
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