Best Approaches to Acute Gastroenteritis

Sara Marlow, MSN, RN, PHN, FNP-C
Monday February 01, 2016
Each year, there are approximately 179 to 350 million cases of gastroenteritis in the United States, resulting in approximately 600,000 hospitalizations.1,2 Alarmingly, the number of gastroenteritis-associated deaths in the United States more than doubled from approximately 7000 in 1999 to beyond 17,000 in 2007. Worldwide, it is currently one of the leading causes of death.3 Patients aged older than 65 make up the majority of these deaths in the United States (83%), two-thirds of which result from Clostridium difficile infection.2

Although the vast majority of gastroenteritis cases in the United States are self-limiting and not life-threatening, the condition remains the cause of considerable morbidity and economic burden.4 Norovirus alone is responsible for $2 billion in health care costs and lost productivity annually,5 and foodborne illnesses impose an overall economic burden exceeding $15.5 billion annually.4 About 90% of foodborne gastroenteritis cases can be attributed to just 5 pathogens.

Learning how to prevent, identify, and treat acute gastroenteritis is imperative for health care providers and public health.

Acute gastroenteritis is inflammation and/or irritation of the digestive tract that can cause nausea, vomiting, diarrhea, and/or abdominal pain that lasts less than 14 days. When symptoms last 14 to 30 days, the condition is considered persistent gastroenteritis. When symptoms last longer than 30 days, it is considered chronic.2

Various pathogens and noninfectious agents cause gastroenteritis, and it is one of the most common infectious disease syndromes.2 In the United States, viral gastroenteritis accounts for about 50% to 70% of acute gastroenteritis cases, with norovirus being the leading cause.2,6 Other causes of acute viral gastroenteritis are presented in Table 17. Since the introduction of the rotavirus vaccine, the incidences of rotavirus gastroenteritis and related hospitalizations have been greatly reduced.8 On the other hand, norovirus is common and highly contagious.

After viral gastroenteritis, another 10% to 15% of acute cases have a parasitic cause, while bacterial gastroenteritis accounts for about 15% to 20% of cases. Types of bacterial gastroenteritis are presented in Table 22.

Infectious diarrhea can also be classified into 2 categories: inflammatory or noninflammatory. Noninflammatory diarrhea is more common, and although the cause is usually viral, it can be bacterial or parasitic in origin, as well. Noninflammatory diarrhea, which is typically less severe than inflammatory diarrhea, causes large, watery stool with cramping but no blood; fecal leukocytes are absent. Common causes of noninflammatory diarrhea are enterotoxigenic Escherichia coli, Clostridium perfringens, Bacillus cereus, Staphylococcus aureus, rotavirus, norovirus, Giardia, Cryptosporidium, and Vibrio cholerae. Inflammatory diarrhea is more severe and caused by toxin-producing bacteria. It disrupts the mucosa, causing bloody diarrhea, abdominal pain, and fever, and fecal leukocytes are present. Common causes of inflammatory diarrhea are Salmonella, Shigella, Campylobacter, Shiga toxin-producing E. coli, enteroinvasive E. coli, C. difficile, Entamoeba histolytica, and Yersinia.9 See Table 32 for other epidemiologic considerations in acute gastroenteritis.2

Travel (in general) E. coli is the most common cause of traveler’s diarrhea. Symptoms usually begin within a few days of arriving and last 5 days to 2 weeks.
Travel to Asia, Africa, and South America 12% of diarrheal illness may be caused by rotavirus.
Asia and Central America Vibrio species is more common.
Travel to developing countries Bacterial and parasitic infections are more common. Giardia lamblia, Aeromonas, and Cryptosporidium are often found in contaminated water.
Recent antibiotic use These patients carry a higher risk for C. difficile infection.
Daycare Children and their families are at higher risk for rotavirus infection.
Homosexual men These men are at higher risk for infection with Shigella, Campylobacter jejuni, Salmonella, and protozoa-like Entamoeba. HIV-infected patients with a CD4 count <200 are at increased risk for infection by Mycobacterium avium complex, microsporidia, cytomegalovirus, and Cystoisospora belli.

In the United States, a large portion of gastroenteritis cases are caused by self-limiting viruses and generally do not require labs or stool culture, unless warranted by certain red flags (Sidebar10-12). A thorough history and physical exam are usually sufficient for diagnosis.

History of Present Illness
  • Onset: Paying close attention to the onset of symptoms can be particularly helpful in making a specific diagnosis, given the various incubation periods among pathogens. Did symptoms begin shortly after eating? Did they occur while traveling to a different country? Did they begin while babysitting? Have the symptoms been ongoing for weeks or years?
  • Location: Are the symptoms generalized nausea and diarrhea or is the patient able to point to a specific area of pain? The abdominal exam is an important part of ruling out red flags. When a patient complains of abdominal pain, the various causes of an acute abdomen or referred pain should be considered. Upper abdominal pain could be acute cholecystitis, pancreatitis, or a perforated ulcer. Mid-abdominal pain could be a sign of intestinal obstruction or mesenteric ischemia. Lower abdominal pain could be appendicitis or sigmoid diverticulitis, or it could have a gynecologic or urologic cause. Patients with gastroenteritis should not have rebound tenderness, guarding, distention, bulges, pinpoint pain, or a board-like abdomen.13
  • Duration: Acute infectious gastroenteritis lasts fewer than 14 days, and most viral cases typically last fewer than 4 days. Symptoms occurring longer than this warrant further investigation.
  • Character: The character of diarrhea and vomit, as well as pain, is especially important when differentiating between viral and bacterial causes of gastroenteritis. The clinician should ask questions about frequency and quality of vomiting and diarrhea. What color is the stool and vomit? Is the stool watery, bloody, explosive, painful, cramping, pale, clay-colored, or dark, or does it have mucus? Is the vomit green, bloody, black, or like coffee grounds? The history should include questions that determine whether the patient is bleeding, if there is significant inflammation, and which part of the gastrointestinal (GI) tract appears to be affected.
  • Associated/aggravating/alleviating factors: Is there a constellation of symptoms or is the vomiting, diarrhea, and/or abdominal pain isolated? If symptoms are isolated, differentials should be reviewed carefully. Do certain foods lead to diarrhea? If the patient frequently experiences gas or diarrhea after eating certain foods, then noninfectious causes such as food intolerances or irritable bowel syndrome should be considered.
  • Pain radiation: Does the pain radiate to the back, to the right lower quadrant, or to the left side? Serious conditions can masquerade as GI symptoms. Sometimes, myocardial infarction can appear as dyspepsia and epigastric pain. In children, abdominal pain may be the only presenting feature in pneumonia.
  • Timing: Asking about the timing of symptoms is crucial in determining whether the condition is chronic, acute, infectious, or noninfectious. Uncovering the exact offending agent in acute gastroenteritis is difficult without a culture and usually unnecessary, as treatment is mostly supportive. However, a good history and physical examination can lead the clinician in the right direction.
  • Severity: Acute viral gastroenteritis is usually less severe than bacterial gastroenteritis. Hydration should be considered when investigating the severity of symptoms, as severe diarrhea or vomiting could quickly lead to dehydration and electrolyte imbalances that can be fatal in vulnerable populations. The very young and the very old, immunocompromised individuals, and malnourished patients are most at risk. Mild to moderate dehydration can cause dry mouth, fatigue, sleepiness, thirst, decreased urine output, dry skin, constipation, and dizziness. Severe dehydration—which is an emergency—can cause extreme thirst, extreme sleepiness, sunken fontanels, and fussiness in infants; irritability/confusion in adults; and dry mucous membranes, little urine to anuria, sunken eyes, tenting, hypotension, tachycardia, rapid breathing, fever, and delirium in individuals of any age. Severe volume depletion can cause bradycardia; deep, erratic respirations; and hypothermia.2

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