Pediatric Gastroenteritis

James Waymack MD
Assistant Professor
Director of Undergraduate Education
Assistant Program Director
Southern Illinois University School of Medicine


  • Identify the causative organisms of pediatric gastroenteritis.
  • Investigate the presenting features of pediatric gastroenteritis.
  • Describe varying severity of dehydration and appropriate treatment. 


Pediatric gastroenteritis is a common illness that accounts for many visits to the Emergency Department. Gastroenteritis is a descriptive term to describe inflammation of the stomach or intestines that is manifested as nausea, vomiting or diarrhea and is considered acute in nature if the duration has been less than two weeks. By definition the diagnosis of gastroenteritis should be supported by historical components of both vomiting and diarrhea. While often a benign and self limited illness there can be severe morbidity and mortality associated with gastroenteritis.

Gastroenteritis can be due to bacterial, viral or parasitic pathogens most often transmitted via the fecal-oral route or through contaminated food or water.  The most common bacterial pathogen in developed countries is Campylobacter jejuni and other common pathogens include Staphylococcus aureus,Salmonella, Shigella and enterotoxigenic Escherichia coli.  While Clostridium difficile is considered the most common cause of antibiotic induced diarrhea in adults it is not in the pediatric population. The most prevalent viral cause of gastroenteritis in children is rotavirus followed by the noroviruses and hepatitis.  Rotavirus has been on the decline due to increasing vaccination rates.  Parasitic causes of acute gastroenteritis may be due to Cryptosporidium parvum, Entamoeba histolytica and Giardia lamblia.

One must also consider other disease processes in the child who presents with abdominal pain, vomiting or diarrhea.  If any of these symptoms appears as an isolated chief complaint or the history is not consistent with sick exposures or ingestion of contaminated food products the differential diagnosis should be expanded to include other congenital or anatomical causes of the symptoms.  Prematurely or incorrectly diagnosing a child with gastroenteritis could lead to misdiagnosis and further morbidity or mortality.

Common Causes of Pediatric Gastroenteritis
BacteriaIncubationSigns and SymptomsDurationAssociated FoodsTestingTreatment
Campylobacter jejuni2-5 daysDiarrhea, cramps, fever, vomiting; diarrhea may be bloody2-10 daysPoultry,


Unpasteurized milk

Contaminated water

Routine stool culture, requires special culture media to grow at 42 CSupportive care, for severe cases erythromycin or quinolones may be indicated. Guillain-Barre syndrome can be a sequela
E. coli 0157 & shiga-toxin producing E. coli1-8 daysSevere diarrhea that is often bloody


Abdominal pain and vomiting.

Usually, little or no fever is present

More common in children less than 4


5-10 daysUndercooked beef



Unpasteurized milk or juice

Raw fruits and vegetables

Contaminated water

Stool culture


0157 requires special culture media

Supportive care, monitor renal function, hemoglobin and platelets closely


0157 can cause hemolytic uremic syndrome

Antibiotics may promote the development of HUS

Enterotoxigenic E. coli1-3 daysWatery diarrhea, abdominal cramps, some vomiting3 to > 7 daysWater or food contaminated with human fecesStool culture


ETEC requires special testing for identification

Supportive care


Antibiotics rarely needed

TMP-SMX and quinolones recommended

Salmonella1-3 daysDiarrhea, fever, vomiting and abdominal cramps4-7 daysContaminated eggs, poultry


Raw fruits and vegetables

Oral-fecal route

Routine stool culturesSupportive care


Antibiotics not indicated unless S. typhi or S. paratyphi with extra-intestinal spread

Consider ampicillin, gentamicin, TMP-SMX or quinolones

Shigella24-48 hrsAbdominal cramps, fever, diarrhea


Stools may contain blood and mucus

4-7 daysFood or water contaminated with human feces


Fecal-oral route

Routine stool culturesSupportive care


TMP-SMX in US if susceptible

Quinolones if resistant

Staphylococcus aureus1-6 hrsSudden onset of severe nausea and vomiting


Abdominal cramps

Diarrhea and fever may be present

24-48 hrsUnrefrigerated or improperly refrigerated meats


Potato and egg salads

Clinical diagnosisSupportive care
Rotavirus1-3 daysVomiting, watery diarrhea, low-grade fever


Temporary lactose intolerance

4-8 daysFecally contaminated foods


Ready to eat foods

Identification of virus in stool via immunoassaySupportive care


Severe diarrhea can require fluid and electrolyte replacement

Norovirus12-48 hoursNausea, vomiting, abdominal cramping, diarrhea, fever, myalgia


Diarrhea more prevalent in adults and vomiting more prevalent in children

12-60 hrsShellfish, contaminated foods, ready to eat foodsClinical diagnosis


Negative bacterial culture

Stool negative for WBCs

Supportive care



Good hygiene

Hepatitis28 days averageDiarrhea, dark urine, jaundice and flulike symptoms


Fever, headache, nausea and abdominal pain

2wk – 3 mosShellfish, raw produce, contaminated drinking waterIncrease in ALT, bilirubin, Positive IgM and anti-hepatitis A antibodiesSupportive care


Prevention with immunization

Entamoeba histolytica2 days to 4 wksDiarrhea (often bloody), frequent bowel movements, lower abdominal painMay be protracted (several weeks to months)Uncooked food or contaminated waterExamination of stool for cysts and parasites, may need at least 3 samples


Serology for long term infections

Giardia lamblia1-2 wksDiarrhea, stomach cramps, gas, weight lossDays to weeksUncooked food, or contaminated waterExamination of stool for ova and parasites, may need 3 samplesMetronidazole
Cryptosporidium2-10 daysDiarrhea (usually watery), stomach cramps, upset stomach, feverRemitting and relapsing for weeks to monthsUncooked or contaminated food, drinking waterSpecific examination of stool for cryptosporidium, may need to examine food or waterSupportive care, self-limited, if severe consider paromomycin for 7 days
Adapted from Nelson’s Textbook of Pediatrics: Chapter 332: Acute Gastroenteritis in Children, Tables 332-1.332-2 and 332-3.


The clinical presentation of patients with acute gastroenteritis is variable depending on the pathogen and the amount of inoculum the patient is exposed to.  The most common symptoms are nausea and vomiting followed shortly after by diarrhea.  Diarrhea may be watery as is often the case with viral causes and toxin-producing bacteria. Invasive bacteria such as Campylobacter, Shigella, Salmonella and enteroinvasive E. coli(shiga-toxin producing) will often produce bloody diarrhea.  In regards to parasitic causes of gastroenteritis, Entamoeba may be associated with bloody diarrhea while large amounts of flatulence could suggest infection with Giardia.   Most causes of gastroenteritis associated symptoms may include fever and abdominal cramping.  If there is a prolonged or severe course of illness dehydration, weight loss and malnutrition may occur.

If the infectious agent produces a preformed toxin, such as S. aureus or Bacillus cereus, vomiting and diarrhea will occur in a matter of hours after ingestion of contaminated food.  In the case of most bacterial pathogens the incubation period will be two to five days.  Viral illnesses have an incubation period of twelve hours to three days and parasitic agents will take two days to four weeks to manifest symptoms. Exposure of a traveler or hiker to untreated water and illness that persists for more than seven days should prompt evaluations for protozoal pathogens.  One of the major clinical features of protozoal diarrheas is a prolonged course.  Patients who have persistent diarrhea should have stools tested for Entamoeba histolytica antigen, Giardia intestinalis antigen, and Cryptosporidium parvum antigen by EIA.

A patient’s medical and surgical history often assists in narrowing the differential diagnosis. The differential diagnosis for diarrhea is broadened for a patient with acquired immunodeficiency syndrome and other immunocompromised states. Medications commonly have nausea, vomiting, and diarrhea as a side effect or sequela. Has the patient traveled outside the United States or to a rural area recently? Rural hiking places the patient at risk for Giardia, particularly if water-purification procedures were not strictly followed, and travel to Third World countries increases the chances of parasitic infection and traveler’s diarrhea. Sexual and occupational histories are also important.

Initial Actions and Primary Survey

As with any patient, the examination begins with the ABC’s. In particular, assessment of hydration status occurs shortly after the physician arrives at the bedside. Like the history, a careful physical examination can help narrow the differential diagnosis.  Upon the initial evaluation of the child presenting with acute vomiting or diarrhea obtaining a history focused on the onset of symptoms, possible sick contacts, exposure to contaminated food or water, the number of emesis and diarrhea episodes, presence of bilious vomiting or hematemesis, melena or hematochezia and any associated symptoms will be helpful in clinically diagnosing acute gastroenteritis.  Clues to the child’s hydration status can also be gained from the parents by way of the history.  Asking questions regarding the patient’s behavior or activity level, oral intake and the amount of wet diapers or voids since the onset of symptoms can suggest if he or she is still adequately hydrated.

If the child exhibits signs of severe dehydration immediate resuscitation measures should be enacted.  Airway and breathing should be assessed for adequacy and intervened upon with endotracheal intubation and mechanical ventilation if the child demonstrates signs of respiratory failure. Full cardiac monitoring with pulse oximetry and frequent blood pressure assessment should be established.  Intravenous access and crystalloid resuscitation with 20 ml/kg boluses should be given.  If IV access is unobtainable intraossesus placement should be considered early in the management of the severely dehydrated patient.

While a complete physical examination should be performed on every pediatric patient, in the case of acute gastroenteritis the most useful components of the exam will come from the child’s vital signs and general appearance assessing for ay signs of dehydration.  The abdomen should also be assessed for distension, bowel activity, tenderness and rigidity that may prompt further consideration of other causes of the child’s acute vomiting or diarrhea if abnormal.  In the case of gastroenteritis the abdomen should be relatively benign with physical exam findings commonly being some mild diffuse tenderness and hyperactive bowel sounds.

Adapted from Nelson’s Textbook of Pediatrics. Chapter 332: Acute Gastroenteritis. Table 332-8.

Symptoms Associated With Dehydration
SymptomMinimal or no dehydration (< 3% loss of body weight)Mild to moderate dehydration (3-9% loss of body weight)Severe dehydration (>9% loss of body weight)
Mental StatusWell; alertNormal, fatigued or restless, irritableApathetic, lethargic, unconscious
ThirstDrinks normally; might refuse liquidsThirsty, eager to drinkDrinks poorly; unable to drink
Heart rateNormalNormal to increasedTachycardia, with bradycardia in most severe cases
Quality of pulsesNormalNormal to decreasedWeak, thread, impalpable
BreathingNormalNormal; fastDeep
EyesNormalSlightly sunkenDeeply sunken
Mouth and tongueMoistDryParched
SkinfoldInstant recoilRecoil < 2 secRecoil in > 2 sec
Capillary refillNormalProlongedProlonged; minimal
ExtremitiesWarmCoolCold; mottled; cyanotic
Urine outputNormal to decreasedDecreasedMinimal

Diagnostic Testing

Laboratory studies may not be necessary for the child who presents with acute gastroenteritis unless the results are severely abnormal.  However, if the child appears moderately or severely dehydrated a basic metabolic profile and glucose measurement may help guide management by assessing for electrolyte imbalance (hyponatremia, hypernatremia or hypokalemia), dehydration (metabolic acidosis), acute renal failure or hypoglycemia.  Infants have a relatively high glucose requirement and low glycogen stores, so they may develop hypoglycemia when energy requirements rise.  Checking blood sugar can be especially important in this population.

Stool cultures and specific pathogen testing are often not necessary as well and the results will require some time to return. Therefore, this testing may not be helpful in the acute management of the child with gastroenteritis.  Stool samples should be obtained for any child who is started on antibiotic therapy, hospitalized or immunocompromised.  Common stool studies include bacterial culture, assessment for leukocytes and occult blood. You should also check with laboratory once the sample is collected as certain culture medium may be required for select pathogens such as Salmonella, Shigella and E. coli O157.  If there has been recent antibiotic use assessment for C. difficile toxin should also be considered, however a fair amount of children are carriers of this organism.


As described above treatment begins with the initial assessment and resuscitation of the child if the show signs of severe dehydration.  If the child appears to be only mildly or moderately dehydrated a trial of an antiemetic such as ondansetron, which is available as a liquid or orally dissolving tablet may be attempted to facilitate oral rehydration.  The fluid of choice for oral rehydration therapy should be an isotonic solution that includes water, sodium, chloride, glucose and bicarbonate.  There are various formulations available the most common being Pedialyte. Care should be taken to avoid hypotonic (pure water) or hypertonic (broth) solutions as these can lead to hypernatremia or hyponatremia, especially in younger child and infants. Total intake should be 30 to 50 ml/kg for the mildly dehydrated child and 60 to 80 ml/kg for the moderately dehydrated child with 25% of the goal intake administered each hour for four hours while being observed in the emergency department.

Empiric antimicrobial therapy is often not required for the child presenting with gastroenteritis.  Antibiotic therapy does not usually decrease the duration of symptoms and may cause further complications for the child.  Consideration for antimicrobial therapy should be made if bloody diarrhea is present, the likelihood for complications is high (age < one year, immunosuppression, septicemia or chronic disease), hospitalization or if stool cultures suggest a specific bacterial pathogen.  If the history supports parasitic infection antimicrobial therapy should be considered as well.

Antidiarrheal compounds are not recommended for children with gastroenteritis as they may prolong infection or cause complications due to an accumulation of bacterial toxins if present.  Probiotics and zinc supplementation are gaining favor in the management of acute gastroenteritis as they may decrease the duration of illness.

Most cases of mild to moderate gastroenteritis can be managed on an outpatient basis given the child is able to maintain hydration.  The child may benefit from a short course of antiemetics on an outpatient basis to avoid vomiting while hydrating.  Aggressive parental education on rehydration as well as monitoring for signs of dehydration is key prior to discharge.  They should be encouraged to follow up with their pediatrician in two to three days for reassessment and return to the Emergency Department for any concerns of worsening or inability to drink.  If there is any concern for deterioration of the patient’s clinical status or the inability to perform oral rehydration after a short course of observation the child should be admitted to the hospital for observation and intravenous fluids.

Pearls and Pitfalls

  • In order to make the diagnosis of gastroenteritis the child should have elements of both vomiting and diarrhea
  • Misdiagnosing more severe medical conditions as gastroenteritis can lead to further morbidity or mortality
  • The mainstay of treatment for gastroenteritis is rehydration, with oral rehydration being preferred if the child is able
  • Stool cultures should be obtained in most children presenting to the Emergency Department with diarrhea
  • Antibiotics are not helpful in most cases of pediatric gastroenteritis unless there is no clinical improvement and stool cultures are positive


  1. Nelson Textbook of Pediatrics, 19th edition. Kleigman Chapter 332: Acute Gastroenteritis in Children.
  2. Rosen’s Emergency Medicine, 8th edition. Marx Chapter 173: Infectious Diarrheal Disease and Dehydration.
  3. Freedman SB, Hall M, Shah SS, Kharbanda AB, Aronson PL, Florin TA, Mistry RD, Macias CG, Neuman MI. Impact of increasing ondansetron use on clinical outcomes in children with gastroenteritis. JAMA Pediatr. 2014 Apr;168(4):321-9. doi: 10.1001/jamapediatrics.2013.4906. PubMed PMID: 24566613.