Gastroenteritis
Acute Care Module
Jonathan Bae, MD
Objectives
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To review epidemiology of acute
gastroenteritis
To review common causes of gastroenteritis
as well as clinical presentation
To differentiate between viral and
bacterial/parasitic types of gastroenteritis
To discuss management strategies of
gastroenteritis
Background
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Gastroenteritis refers to an acute inflammation of the stomach
and intestines resulting in vomiting and diarrhea
Gastroenteritis is one of the most common diseases affecting
children
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Second most common acute infection after URI
Viruses are the most common causes of acute gastroenteritis in
developed and developing countries
Gastroenteritis is a substantial cause of morbidity in pediatric
populations
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Worldwide, acute gastroenteritis is the leading cause of illness and
death for children
Epidemiology
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Approximately 5 billion episodes of diarrhea/gastroenteritis occur
worldwide annually
In children <5 years old, there are 1-5 episodes per child-year
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1 in 50 children are hospitalized during childhood due to acute
gastroenteritis
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Accounts for 15-25 million episodes of gastroenteritis annually resulting in
3-5 million doctor visits and 200K hospitalizations
Highest rate of infection occurs between 3-24 months of age
95% occur less then 5 years of age
3-5% of all hospital days and 7-10% of hospitalizations annually for
patients <18 are due to viral gastroenteritis
70-90% occur in winter
Gastroenteritis accounts for 15-30% of death in developing nations
Transmission
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Fecal-oral route
Contaminated food and water
Daycare, school
Respiratory tract inoculation?
Pathogenesis
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Viral: infect enterocytes leading to destruction 
transudation of fluid into intestinal fluid
Bacterial:
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Toxin production (Vibrio cholerae, Clostridium difficile,
Staph)  secretory diarrhea
Bacterial adherence (E. Coli) release of mucinase,
protease resulting in cell death  osmotic diarrhea
Invasion (Shigella)
Parasites: Invasion or adherence to bowel wall
resulting in cell destruction
Disruption of enterocytes leading to transudation/exudation of fluid, often with
loss of ability to digest food (complex sugars) and absorb food until return of
normal villous architecture.
Clinical Presentation
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Diarrhea
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Frequency, color, consistency, odor, blood, mucus, duration
Nausea/vomiting
Fever
Anorexia
Abdominal pain/cramping
Headache
Myalgias
Dizziness/lightheadedness
Daycare attendance
Recent antibiotic use
Dietary indiscretions; inadequate storage and preparation of food
Rapid onset
Travel
Animal exposure (domestic, wild, farm)
Risk Factors for severe manifestations
or hospitalization
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Children <4 years
Lower socioeconomic status
Poor capability of parents
First time infection
Malnutrition
Immunodeficiency
Change in serotype of infecting strain
Large inoculum size
Strain virulence
Loss of maternal immunity
Physical Exam
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Fever
Weight loss
Tachycardia
Orthostasis
Tachypnea
Hypotension
Somnolence/Level of
consciousness
Dry membranes
Flat fontanel
Loss of skin turgor
Physical exam should focus on
signs of clinical dehydration
which helps to assess
severity of illness
Laboratory Evaluation
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Elevated specific gravity on urinalysis
Isotonic dehydration
Metabolic acidosis
Stool gram stain, culture, and electron microscopy (viruses),
ova & parasites
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Fecal leukocytes
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Labs routinely test for Salmonella, Shigella, and Campylobacter
Nonspecific evidence of inflammation
Most common for bacterial/parasitic gastroenteritis  indicative of
invasive diarrhea
Fecal blood  suggests invasive organism (hemorrhagic E.
Coli)
Specific assays  rotavirus, C. diff
Differential Diagnosis
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Extraintestinal infections (UTI, AOM, URI)
Lactose intolerance
Bacterial sepsis
Meningitis
Pyloric stenosis
Bowel obstruction
Intussusception
Diabetic ketoacidosis
Toxin ingestions
Antibiotic use
Overfeeding
Food protein allergy
Celiac disease
Inflammatory Bowel Disease
Malabsorption
Malignancy (neuroblastoma, carcinoid, VIPoma, gastrinoma)
Viral vs. Bacterial
Viral gastroenteritis accounts for 70-90% of cases
Bacterial gastroenteritis 10-20%
Bacterial
 Tend to affect children
>2 years of age
 Blood often present
 Fecal leukocytes often
present
 May be associated with
travel, exposure to
animals, consumption
of meat
Viral
 Tend to affect children
<2 years
 Blood absent
 Fecal leukocytes
absent
 Not often associated
with travel, animals, or
meat
Viral Gastroenteritis
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Rotavirus
Calcivirus (Norwalk)
Enteric adenovirus (serotypes 40 & 41)
Astrovirus
Rotavirus
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The most common cause of acute gastroenteritis
70-nm, double-stranded, segmented RNA virus
Fecal-oral route
Peaks in winter; common spread among daycare
Highest incidence ages 6 months to 2 years
Infects and destroys enterocytes in the small
intestinge
Incubation for approximately 2 days
Vomiting and watery diarrhea x 3-8 days
May have associated fever and abdominal pain
Calcivirus (Norwalk)
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Described after an outbreak among school children
in Norwalk, Ohio in 1972
27-nm RNA virus
Incubation 1-2 days
Fecal-oral transmission
More common in older children and adults
Vomiting, diarrhea +/- fever, abdominal pain
Outbreaks after ingestion of contaminated shellfish,
salad (cruise ships)
Adenovirus
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Enteric subtypes 40 & 41
Similar to rotavirus but with longer course (>6
days)
Common year round
Typically affects older children
Bacterial Gastroenteritis
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Campylobacter jejuni
E. Coli
Salmonella
Shigella
Yersinia enterocolitica
Vibrio cholera
C. Diff
Staph
Bacillus cereus
Campylobacter jejuni
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Curved gram negative organism
Most commonly isolated bacterial fecal pathogen
Less common: C. fetus, C. abortus
Common in summer
Affects large bowel
Grossly bloody diarrhea, fever, abd pain; may mimic
appendicitis
Animal reservoirs include dogs, cats, wild birds,
poultry
Escherichia coli
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Gram-negative rod with four different subclasses named for distinct
mechanisms of action
Enterotoxigenic E. coli
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2.
Enteropathogenic E. coli
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Infects and disrupts enterocytes
Musty smelling stool w/o blood or mucous
Enteroinvasive E. coli
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Toxin similar to cholera
Watery, large volume diarrhea
Similar to shigella
Enterohemorrhagic E. coli
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Cytoxins result in destruction of enterocytes
Bloody diarrhea
O157:H7 subclass associated with hemolytic uremic syndrome (acute
renal failure, microangiopathic hemolytic anemia, thrombocytopenia,
fever)
Salmonella
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Non-lactose fermenting, motile GNR
S. enteritidis, S. choleraesuis, S. typhi
Late summer, early fall
Enterocyte invasion in small bowel\
Foul smelling, soft stool +/- blood, mucus; stool
leukocytes
Fecal-oral route, contaminated food, reptiles
(turtles), eggs/poultry  needs large inoculum size
May have asymptomatic carrier state or be
complicated by bacteremia, osteomyelitis
Shigella
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Non-lactose fermenting, nonmotile GNR
S. sonnei, S. flexneri (more common in US); S. dystenteriae
(developing countries)
Most common in fall
Enterocyte invasion in large bowel
Watery, bloody, or mucous stool with fruity or vinegary smell; stool
leukocytes
Associated with fever, abdominal pain, tenesmus, headache
Daycare, contaminated food/water  only requires small inoculum
Complications include toxic megacolon, cholestatic hepatitis, HUS,
Reiter syndrome, seizures
Rx with IV 3rd generation cephalasporins (Ceftriaxone)
Yersinia enterocolitica
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Nonlactose fermenting, aerobic, motile gram
negative coccobacillus
Most common in winter
Affects small bowel (ileum)Loose bloody, mucous
diarrhea; fecal leukocytes
Complications include erythema nodosum, reactive
arthritis, terminal ileitis, mesenteric adenitis (may
mimic appendicitis), meningitis, myocarditis,
hepatitis, glomerulonephritis
Vibrio cholerae
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Aerobic, motile, curved, gram-negative
Occurs in epidemics
Affects small bowel via enterotoxin
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Attaches with flagella and release cholera toxin which
causes rapid and severe fluid loss
Large voluminous, explosive diarrhea; crampy
abdominal pain
Complicated by severe hypovolemia and death
Uncooked crustaceans, mollusks (oysters, crabs,
shrimp); requires large inoculum
Other bacterial pathogens
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Clostridium difficile
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Staphylococcal
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Colitis results in overgrowth after antibiotic administration (ampicillin, clindamycin,
cephalosporins) with subsequent toxin production  pseudomembranous colitis (lined
with gray plaque-like lesions)
Symptoms may not appear for weeks after abx
Abdominal pain, fever, blood/mucous stool; fecal leukocytes
Rx with flagyl or vancomycin
Disease mediated by enterotoxin
Produces primarily nausea, vomiting, and retching followed by diarrhea
Brief incubation period (3-5 hrs)
Contaminated food (mayonaise)
Antibiotics of no help  toxin mediated
Bacillus cereus
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Soil dwelling, gram positive rod
Heavy vomiting, retching, abdominal pain
Toxin mediated symptoms, often resulting from contaminated food with bacterial
spores “Fried Rice Syndrome” (improperly refrigerated cooked rice)
Parasites
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Giardia lamblia
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Entamoeba histolytica
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Ingestion of infected cysts resulting in loose, bloody, mucoid diarrhea
May be complicated by hepatic abscess
Cryptosporidium
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Flagellated protozoan; cyst form is the infectious agent which infest the
duodenum via fecal-oral route
Contaminated fresh water streams, day care centers
Flatulence, abdominal pain, mucous diarrhea
Higher risk for severe disease with IgA deficiency or cystic fibrosis
Diagnosed by direct inspection of stool or ELISA
Daycare settings, immunocompromised hosts (HIV)
Frequent, watery stools
Isospora
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Common in HIV/AIDs
Initial Assessment
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Duration of illness
Number of episodes
Fever
Presence of blood or mucous in stool
Fluid intake
Activity level
Moisture of mucous membranes
Urine frequency
Ill contacts, travel, food
Underlying illness
Management
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Mainstay of therapy is management of fluid
and electrolyte abnormalities
Antibiotics rarely indicated
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May result in prolonged shedding
No benefit to the use of antiperistaltic agents
Controversial benefit to probiotics and
antiemetics
Hospital Admission
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Shock
Severe dehydration
Seizures
Anuria > 12 hrs
Hematemesis, hematochezia
Metabolic imbalance
Mild-moderate dehydration if cannot ensure successful oral
rehydration (intolerant, vomiting)
High frequency of stools or vomiting
Concerns about caregivers
Immunocompromised hosts
Prolonged diarrhea (> 7 days) w/no improvement
Assessment of Dehydration
Fluid resuscitation
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Severe dehydration/hypovolemia
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Rapid fluid resuscitation with isotonic fluid (normal
saline or LR)
Mild to moderate dehydration
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May replace with oral rehydration solutions given
“little and often” (~ 5 ml q1-2 minutes)
Deficit should be replaced over 3-4 hours
If child is intolerant, may consider NG tube or
parenteral administration
Refeeding (Maintenance)
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AAP and CDC recommend resumption of an ageappropriate diet after completion of rehydration
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Unrestricted diets shown to reduce stool output and
duration of disease
Breastfeeding should continue through the rehydration
phase
BRAT (Bananas, rice, applesauce, toast) and clear liquids
well tolerated but restrictive and have suboptimal nutritional
value
Antibiotics
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Not indicated for viral gastroenteritis
If bacterial or parasitic causes of
gastroenteritis are suspected, confirm with
culture before initiation of antibiotics
If organism isolated, antimicrobial therapy
may be indicated
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May prolong shedding (Salmonella)
Refer to Red Book
Antiemetics & Antimotility Agents
Antiemetics: use is controversial
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Cochrane review: Reglan and zofran
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Small number of trials showed some benefit in reducing the number of episodes of
vomiting over placebo
There was increased incidence of diarrhea in antiemetic group, thought to be
secondary to retention of fluid and toxins that would have been eliminated by
vomiting.
May be of some benefit
Promethazine: no demonstrable benefit
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Increased risk of respiratory depression (black box warning) and dystonic reactions
Not to be used <2 years
Antidiarrheal agents (Loperamide)
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No data to prove benefit
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Potential for side effects: lethargy, paralytic ileus, toxic megacolon, CNS
depression
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Delays transit time  prolong course of bacterial diarrheas
Probiotics
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Microbial cell preparations or components of microbial
cells that have beneficial effects on human health
Lactobacillus
Compete for available nutrients and binding sites, thus
acting against enteric pathogens
Cochrane review of 23 studies
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Reduced risk of diarrhea and duration of illness
May be some benefit in acute infectious gastroenteritis in
addition to rehydration therapy
Prevention
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Hand washing!
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Rotavirus vaccine
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Pentavalent vaccine administered orally at 2, 4, 6 mths of age; first dose b/w 6-12 wks
(no later then 12 weeks) and all doses administered before 32 weeks
Will prevent 75% of rotavirus cases, 98% of severe cases, and 96% of hospitalizations
due to rotavirus
2, 4, 6 months
Diaper changing
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Excretion can begin before symptoms and continue after symptoms resolve
Asymptomatic infection common route of spread
Changing area should be separate from food preparation area
Diapers should be placed in occlusive bags
Cleaning solution
Water purification
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More of an issue in developing countries
Boil water for 10 minutes or using chlorine containing tablets
Summary
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Acute gastroenteritis is a leading cause of morbidity
nationwide leading to dehydration, hospital
admission, and rarely, death
Viral causes (rotavirus) predominate as the
pathogen
Initial management rely on assessment of severity of
dehydration and fluid resuscitation
Early refeeding after resuscitation is the goal for
maintenance of hydration
Some possible benefit to probiotics and antiemetics
(reglan, zofran)
Antibiotics rarely indicated
Prevention is key  HANDWASHING!
References:
Alhashimi D, Alhashimi H, Fedorowicz Z. Antiemetics for reducing vomiting related
to acute gastroenteritis in children and adolescents. Cochrane Database of
Systematic Reviews 2006, Issue 4. Art. No.: CD005506. DOI:
10.1002/14651858.CD005506.pub3.
Allen SJ, Okoko B, Martinez E, Gregorio G, Dans LF. Probiotics for treating
infectious diarrhoea. Cochrane Database of Systematic Reviews 2003, Issue 4.
Art. No.: CD003048. DOI: 10.1002/14651858.CD003048.pub2.
Armon, K., et al. “An evidence and consensus based guideline for acute diarrhoea
management.” Arch Dis Child, 2001; 85: 132-142.
Matson, David. “Epidemiology, pathogenesis, clinical presentation, and diagnosis of
viral gastroenteritis in children.”
Matson, David. “Prevention and treatment of viral gastroenteritis in children.” UpTo-Date, 2008
Rudolph, A., et al. “Infectious Diarrhea.” Rudolph’s Fundamentals of Pediatrics, 3rd
edition. 2002: 356-60.