Acute gastroenteritis is a common illness worldwide that causes vomiting and/or diarrhea. It can be life-threatening for children in developing countries, resulting in millions of deaths per year. The causes include viruses and bacteria transmitted through contaminated food or water. Treatment focuses on rehydration. Antibiotics may be used in severe cases but are generally not needed as most cases resolve without medication. Preventive measures include proper food and water sanitation.

1. Acute Gastroenteritis

2. Acute Gastroenteritis
• Acute gastroenteritis is a common illness that
affects persons of all ages worldwide. It is a
leading cause of mortality among children in
developing countries, accounting for an
estimated 2.4 to 2.9 million deaths each year

3. Signs and Symptoms
• Acute onset of vomiting and/or diarrhea
• Fever
• Nausea
• Abdominal cramps
• Anorexia
• Malaise

4. Setting
• Viral
– More common in settings with poor hygiene and
sanitation
• Bacterial
– More common in settings with poor hygiene and
sanitation

5. Infectious Dose
• Viral
– Low (10-100 viral particles) for most agents
• Bacterial
– High (>105 bacteria) for Escherichia coli,
Salmonella, Vibrio; medium (102-105 bacteria) for
Campylobacter jejuni; low (10-100 bacteria) for
Shigella

6. Seasonality
• Viral
– year-round occurrence in tropical areas
• Bacterial
– More common in summer or rainy months,
particularly in developing countries with a high
disease burden

7. Incubation Period
• Viral
– 1-3 days for most agents; can be shorter for
norovirus
• Bacterial
– 1-7 days for common agents (e.g., Campylobacter,
E. coli, Shigella, Salmonella); few hours for
bacteria producing preformed toxins (e.g.,
Staphylococcus aureus, Bacillus cereus)

8. Reservoir
• Viral
– Primarily humans
• Bacterial
– Depending on species, both human (e.g., Shigella,
Salmonella) and animal (e.g., Campylobacter,
Salmonella, E. coli) reservoirs exist.

9. Fever
• Viral
– Common with rotavirus and norovirus;
uncommon with other agents
• Bacterial
– Common with agents causing inflammatory
diarrhea (e.g., Salmonella, Shigella)

10. Vomiting
• Viral
– Prominent and can be the only presenting feature,
especially in children
• Bacterial
– Common with bacteria producing preformed
toxins; less prominent in diarrhea due to other
agents

11. Diarrhea
• Viral
– Common; nonbloody in almost all cases
• Bacterial
– Prominent and frequently bloody with agents
causing inflammatory diarrhea

12. Duration
• Viral
– 1-3 days for norovirus and sapovirus; 2-8 days for
other viruses
• Bacterial
– 1-2 days for bacteria producing preformed toxins;
2-8 days for most other bacteria

13. Diagnosis
• Viral
– This is often a diagnosis of exclusion in clinical practice.
Commercial enzyme immunoassays are available for
detection of rotavirus and adenovirus, but identification of
other agents is limited to research and public health
laboratories.
• Bacterial
– Fecal examination for leukocytes and blood is helpful in
differential diagnosis. Culture of stool specimens,
sometimes on special media, can identify several
pathogens. Molecular techniques are useful epidemiologic
tools but are not routinely used in most laboratories.

14. Treatment
• Viral
– Supportive therapy to maintain adequate hydration
and nutrition should be given. Antibiotics and
antimotility agents are contraindicated.
• Bacterial
– Supportive hydration therapy is adequate for most
patients. Antibiotics are recommended for patients
with dysentery caused by Shigella or Vibrio cholerae
and for some patients with Clostridium difficile colitis.

15. Therapy
• Oral rehydration solutions (ORS) —The most important risk with
diarrheal illness is dehydration. Initial treatment must include rehydration.
Patients with mild diarrhea can ingest extra fluids, such as fruit juices, with
Saltine crackers. Patients with more severe diarrhea require oral
rehydration solutions. These are effective because in small bowel
diarrhea, intestinal glucose absorption via sodium–glucose cotransport
remains intact. The World Health Organization (WHO) recommends that
oral rehydration solutions (ORS) contain the following (per 1 L of water):
• 3.5 g sodium chloride;
• 2.9 g trisodium citrate or 2.5 g sodium bicarbonate;
• 1.5 g potassium chloride; and
• 20 g glucose or 40 g sucros

16. Empiric Antibiotic Treatment
• Empiric antibiotic therapy is rarely indicated for
the treatment of acute infectious diarrhea. Most
cases are effectively resolved by the host's
cellular and humoral defense mechanisms. Fifty
percent of cases of infectious diarrhea resolve in
less than 3 days without antibiotics. Antibiotic
therapy may result in prolonged duration of fecal
excretion of the enteric pathogen, drug-related
side effects (including C difficile diarrhea), and
the development of bacteria resistant to multiple
antibiotics. Antibiotic therapy may be considered,
however, in these selected circumstances:

17. Empiric Antibiotic Treatment
• 1) patients who present with signs and symptoms of
bacterial diarrhea such as fever, bloody stools, and the
presence of fecal leukocytes or occult blood in the stool;
• (2) to reduce fecal excretion and environmental
contamination by a highly infectious agent (eg, Shigella);
• (3) for persistent or life-threatening diarrheal infections
(eg, cholera);
• (4) for traveler's diarrhea, to accelerate resolution of
symptoms in individuals who cannot afford to be
indisposed by illness (eg, politician, concert pianist); or
• (5) for the immunocompromised host. Oral
fluoroquinolones given twice a day for 3–5 days are
suggested

18. Symptomatic Therapy
• Antimotility agents, including diphenoxylate (Lomotil)
and loperamide (Imodium), may be used for the
symptomatic treatment of acute diarrhea to reduce the
number of bowel movements and diminish fluid and
electrolyte losses. These agents should be avoided in
the presence of fever or bloody stools. The dose of
loperamide is 4 mg initially, then 2 mg after each
unformed stool, not to exceed 16 mg/d for 2 days. The
dose of diphenoxylate is 4 mg (two tablets) four times
a day for not more than 2 days. Diphenoxylate has
central opiate effects and may cause cholinergic side
effects.

19. Diagnostic Testing
• Diagnostic testing should not be performed routinely as most cases of
acute diarrhea are self-limited. Diagnostic testing should be reserved for
patients with severe illness, as suggested by one or more of the following:
• Profuse diarrhea with dehydration.
• Grossly bloody stools.
• Fever (oral temperature >38.5°C).
• Passage of more than six unformed stools per day or duration of illness
>48 hours.
• Severe abdominal pain.
• Diarrhea in the immunocompromised or elderly.

20. Prevention
• FOOD AND WATER PRECAUTIONS
• PROPHYLACTIC MEDICATIONS