Gastroenteritis in Emergency Medicine Clinical Presentation

A well-taken history, considering important epidemiologic factors, can help to identify not only the cause of diarrhea but also the patient at risk for complications. History in infectious and food poisoning cases varies depending on the agent, with variation in the onset; the frequency and consistency of the stools; the presence or absence of blood and mucus, and associated vomiting, cramps, or fever. The history should also identify risk factors for unusual causes of acute gastroenteritis and possible reasons to suspect noninfectious etiologies. Indications of dehydration or sepsis should also be sought.

As an example, norovirus is usually diagnosed by history. The incubation period for the norovirus is between 12 and 48 hours. Some of the early symptoms include nausea, a sudden onset of vomiting, moderate diarrhea, headache, fever (~50%), chills, and myalgia and will last 12-60 hours. The clinical factors suggestive of norovirus include the patient's presentation and the sudden onset of symptoms, with uncontrolled vomiting being a classic sign. Usually, more vomiting than diarrhea occurs. The natural course of this illness usually provides resolution within 36 hours.

• Duration of illness

  • Duration and rapidity of symptom onset are important in determining the incubation period and possible infecting organism and in directing further care.
  • Diarrhea that lasts longer than a month requires consideration of a different spectrum of etiologic factors than diarrhea that lasts less than 1-2 weeks.
• Fever

  • The presence of high fever (with or without chills) generally suggests that an invasive organism is the cause of diarrhea, although many extraintestinal illnesses can present with both fever and diarrhea, especially in children.
• Vomiting

  • Vomiting, a symptom common to a host of illnesses, implies proximal bowel involvement, especially with preformed neurotoxin, as elaborated by S aureus and B cereus.
  • Vomiting is a leading symptom of intestinal obstruction, usually coupled with distention or if the patient has had gastric bypass surgery; however, distention may not be significant if the obstructing lesion is very proximal. Vomiting without diarrhea must always prompt a search for noninfectious causes and cannot be referred to as gastroenteritis.
• Pain

  • The location and character of pain may be indicative of the area of infection because colonic involvement is usually associated with tenesmus and pain in either of the lower quadrants or the lower back, whereas jejunoileal infection may result in periumbilical pain.
  • Cramps may be caused by an electrolyte imbalance.
  • Pain, especially in patients older than 50 years, should raise the suspicion of an ischemic process.
• Stools

  • Ask about frequency, amount, color, consistency (ie, watery, semisolid, odor), and presence of blood and/or mucus.
  • Large volumes of stool are usually associated with enteric infection, whereas colonic infection results in many small stools.
  • The presence of blood may indicate colonic ulceration (bacterial infection, inflammatory disease, ischemia).
  • White bulky feces that float (high fat content) are due to a small bowel pathology that leads to malabsorption.
  • Copious (rice water) diarrhea is a hallmark of cholera.
• Extraintestinal causes

  • A history of any nonintestinal illnesses that can lead to diarrhea should be obtained. Vomiting and/or diarrhea may be a manifestation of that illness or a result of its treatment. Obtaining a history of recent surgery or radiation, food or drug allergies, and endocrine or gastrointestinal disorders is extremely important. The patient should always be questioned regarding prior episodes.
  • Malaria, Whipple disease, irritable bowel, incomplete bowel obstruction, inflammatory bowel disease, nutritional disease, and carcinoid and malabsorption syndromes can all result in diarrhea and are examples of the numerous possible noninfectious cases.
  • Drugs such as colchicine, quinidine, antimicrobials, cancer chemotherapeutic agents, and magnesium-containing antacids frequently cause diarrhea.
• Dehydration

  • Orthostasis, lightheadedness, diminished urine formation, and a change in mentation are symptoms of marked dehydration, requiring aggressive treatment.
  • These symptoms are particularly important in elderly patients, a group that is most at risk from diarrhea.
  • Severe dehydration may also be associated with significant electrolyte imbalances.
• Epidemiologic factors

  • A number of historical questions may provide clues to the etiology of the illness, including foreign travel, recent camping, recent antibiotic use, daycare attendance, and/or ingestion of raw, possibly spoiled, or new marine products, as well as similar illnesses in family, friends, or close contacts.
  • An epidemiologic factor may be travel to developing countries where bacterial or parasitic agents are endemic and can cause infection or to campgrounds in developed regions, where agents such as Giardia lamblia, Aeromonas, and Cryptosporidium can contaminate untreated water.
  • Enterotoxigenic E coli is the most frequent cause of traveler's diarrhea. Symptoms usually begin within days of arrival in the region and can last from 5 days to 2 weeks.
  • Vibrio species are more common in Asia, although epidemics have occurred in Central America within the last 10 years.
  • As many as 12% of diarrheal illness cases may be caused by rotavirus in travelers to Asia, Africa, and South America.
  • Men who are homosexual are more prone to infection by usual pathogens (ie, Shigella, Campylobacter jejuni, Salmonella, protozoalike Entamoeba) via the fecal-oral route. Anal receptive intercourse may result in the direct inoculation of Neisseria gonorrhoeae, Chlamydia trachomatis, Treponema pallidum, and herpes simplex virus. Severely immunocompromised states (CD4 cell count < 200) increase the risk of infection by agents such as Mycobacterium avium complex, microsporidia, cytomegalovirus (CMV), and Isospora belli.
  • Recent use of antimicrobial drugs increases the risk of C difficile infection.
  • A common source outbreak from contaminated water and food may cause gastroenteritis either by infection (eg, C jejuni, G lamblia) or by ingestion of a preformed toxin (eg, E coli O157:H7, scombroid, ciguatera).
  • Infections via the fecal-oral route are prevalent in children who attend daycare centers. Rotavirus has an infection rate of nearly 100% in exposed children younger than 2 years. Other family members are also at risk for infection.
  • Exposure to a public vomiting episode in a public location such as cruise ship or casino can lead to exposure to aerosolized norovirus infection.

A thorough physical examination is essential to assess the general state of hydration and nutrition and to exclude extraintestinal causes of diarrhea. Usually, the cause of diarrhea cannot be determined based on the physical findings present, which may be few.

• The most important element of the physical examination is the assessment of the patient's hydration status. (Dehydration in children, for example, is classified according to the degree of hydration/percentage deficit as < 3%, none; 3-6%, mild; 6-9%, moderate; and >10%, severe.) Additionally, signs of bacteremia or sepsis should be sought. Patients with chronic diarrhea may need an evaluation of their nutritional status.
• A rectal examination should be performed, involving checking for blood and mucus. Rectal examination may reveal abscesses, fistulae, and fissures, which may indicate inflammatory bowel disease. A partially obstructing tumor or a fecal impaction may be discovered as a cause of diarrhea. Finally, the stool can be examined for the presence of blood and pus.
• Hydration and nutritional status

  • Diminished skin turgor, weight loss, resting hypotension and tachycardia, dry mucus membranes, decreased frequency of urination, changes in mental status, and orthostasis can be used to gauge dehydration.
  • In children, the absence of tears, poor capillary refill, sunken eyes, depressed fontanelles, increased axillary skin folds, and dry diapers all may reflect a dehydrated state.
  • Muscle wasting and signs of neural dysfunction due to nutritional depletion may be observed in patients with chronic diarrhea.
• Abdominal examination

  • A careful abdominal examination is necessary to exclude causes of diarrhea that may require surgical intervention.
  • The examiner should look for signs of an acute abdomen, listening for bowel sounds, determining the location of any tenderness, and palpating for masses or organomegaly, rebound, guarding, distension, or rigidity.
  • Appendicitis in children may manifest as diarrhea.
  • Extreme caution should be exercised in post gastric bypass bariatric surgery patients, as they may not manifest typical signs/symptoms such as vomiting or distension with obstruction or ischemia.

• Viral (50-70%)

  • Norovirus
    • This is the leading cause of viral gastroenteritis in the United States. Noroviruses (formerly known as Norwalk virus in the United States and as small round structured virus [SRSV] in the United Kingdom), along with the sapoviruses (formerly known as Sapporo-like viruses), are members of the Caliciviridae family of viruses. The norovirus is a small, 26-40 nm, nonenveloped, single-stranded RNA virus classified as a Calicivirus. Sapoviruses, a cause of gastroenteritis, predominantly in children, are also in the Caliciviridae family. Five norovirus genogroups have been identified: GI, GII, GIII, GIV, and GV; many clusters (genotypes) have also been identified. In 2010, the land-based experience was far busier than usual. The dominating strain was GII-4 (New Orleans). Norovirus is often called the "winter vomiting disease" in Britain and the incidence seems to be higher in colder weather.
    • It is a highly infectious virus—with as few as 10-100 particles necessary for transmission—and is quite resistant to quaternary ammonia compounds, alcohol, detergent-based compounds, freezing, and heat (to 60^o C). It is a very difficult virus to culture and measure; thus, studies on norovirus are limited, with researchers using a "surrogate," nonenveloped virus, Feline Calicivirus (FCV), to assess the efficacy of disinfectants and other mitigation strategies. Some researchers have questioned the use of FCV as a surrogate since FCV is a respiratory virus and norovirus is a GI virus and likely is more resilient than FCV due to the need for norovirus to survive in the hostile environment of the gut. Therefore, the results of testing performed to validate the efficacy of disinfectants and hand sanitizers possibly overestimate the actual effectiveness of these products on human norovirus.
    • Recently, it has been suggested that murine norovirus (MNV) can serve as a useful tool in assessing the risk of infection with human norovirus. It has been used as a surrogate to evaluate the resistance of human norovirus to disinfectants due to it similar characteristics (ie, resistance to basic and acidic pHs, capsid structure, genomic organization, and replication cycle) to human norovirus.^[7]
    • Various modes of transmission exist including fecal-oral transmission (predominant), person to person, fecal contamination of food and/or water, fomite transmission, and airborne spread when in close proximity of someone vomiting, as the virus is easily aerosolized.
    • Between January 1996 and November 2000, 348 outbreaks of norovirus were reported to the CDC. Out of these, 54% of patients were contaminated by food, 17% by person to person, 4% by water, and 25% by unidentified sources. Most of the food sources responsible were identified as oysters, salads, salad dressing, sandwiches, deli meats, cake and frosting, raspberries, drinking water, and ice. Shellfish have been implicated in some outbreaks, but it is not a frequent source on cruise ships, where the predominant mode of infection is believed to be fecal-oral and person to person from individuals who come onto the ships ill and do not report the illness or quarantine themselves in their cabins.
    • Public vomiting episodes with aerosolization of the virus is likely a major source of spread in congested public locations such as cruise ships, schools, and casinos. The same study reveals that 39% contracted the disease in restaurants, 30% in nursing homes, 12% at school, 10% on vacation, and 9% remain unidentified.
    • The incubation period for the norovirus is between 12 and 48 hours. Some of the early symptoms include nausea, a sudden onset of vomiting, moderate diarrhea, headache, fever (~50%), chills, and myalgia and will last 12-60 hours. The clinical factors suggestive of norovirus include the patient's presentation and the sudden onset of symptoms, with uncontrolled vomiting being a classic sign. Usually, more vomiting than diarrhea occurs. The virus is noninvasive of the colon; therefore, WBCs are not seen in the stool, and hematochezia is rare. The severity and length of illness seen is often related to the then current predominant strain.
    • The natural course of this illness usually provides resolution within 36 hours. Unless the patient is very young, very old, debilitated with severe underlying disease, or immunocompromised, they usually do very well with this self-limited illness responding to oral rehydration and a rapid return to normal diet once the vomiting has ceased. The only therapy is oral and/or intravenous hydration with occasional need for antiemetics. The usual cautions concerning the use of antiemetics in very young patients apply. Although viral shedding has been reported for up to 2 weeks or more, the polymerase chain reaction (PCR) testing used to determine this may just be detecting inactivated RNA. The length of viral shedding, the large number of viruses shed in stool (millions) relative to the number required for infection (10-100) explains the communicability and the need for education as to meticulous hand hygiene.
    • There are many norovirus strains with no cross-immunity, so repeat infections are possible throughout one's lifetime.
  • Caliciviruses (Various caliciviruses, other than norovirus, are likely responsible for many outbreaks of previously unidentified viral gastroenteritis.)
  • Rotavirus (This is the leading cause of gastroenteritis in children, but rotavirus can also be found in adults. Rotavirus may cause severe dehydration. - See Pediatric Gastroenteritis)
    • Rotavirus is a nonenveloped, double-stranded RNA virus of the Reoviridae family with a wheel-like appearance under electron microscopy—hence the name. The virus is extremely contagious. Nearly all children are infected with rotavirus at some point before age 5 years, unless immunized. There are now 2 commercially available vaccines in the United States, each with antibodies to multiple strains. Prior to this, there were 55,000–70,000 hospitalizations per year in United States The illness lasts 3-8 days and usually starts with some vomiting, followed by severe foul-smelling (distinctive) diarrhea, potentially leading to severe dehydration.
    • Adults can be infected with rotavirus, although symptoms are usually not as severe. Those adults most likely to be infected include people with children affected by the virus, elderly persons, and the immunocompromised. There are multiple strains (4 are common in the United States), so people can be infected with rotavirus multiple times. Usually, the first infection is the most severe. Most initial infections occur by age 2 years. Rotavirus is considered the most significant etiological agent for acute GI illness in children worldwide, with up to 800,000 annually. The peak rotavirus season is November to April (cooler weather) in temperate weather and year-round in tropical climates.
  • Adenovirus
  • Parvovirus
  • Astrovirus
  • Coronavirus
  • Pestivirus
  • Torovirus
• Bacterial (15-20%)

  • Shigella
  • Salmonella
    • Salmonella appears as the second most common agent among outbreaks with known pathogens. It is manifested by acute enterocolitis, with abdominal pain, diarrhea, nausea, headache, sometimes vomiting, and almost always fever. Infected persons may develop a localized infection or septicemia. Salmonellosis is predominantly foodborne, and, on average, the onset of symptoms occurs 12-36 hours after ingestion of the contaminated source. It is estimated that Salmonella is responsible for approximately 1.4 million infections in the United States each year, of which only about 40,000 are reported. Over 2,500 serotypes of Salmonella have been described, but S typhimurium and S enteritidis are the most commonly detected in infected persons.
    • The incidence of S typhimurium has increased since 1997 and it was the cause of the multistate outbreak associated with peanut butter and other peanut-containing products that resulted in 714 cases across 46 states. The outbreak began in the summer of 2008; however, the epidemiologic investigation was initiated in November due to the inherent time lag in reporting (stool sample results may take 2 wk). The problem became evident when there was a growing cluster of Salmonella serotype typhimurium isolates with the same pulsed-field gel electrophoresis (PFGE) pattern in several states.
    • Review of detailed epidemiologic questionnaires, assessment of foods, and results of case-control studies in industrialized settings where clusters appeared led to the assumption of peanut butter being the common source of the outbreak. The FDA inspected the facility where the peanut butter was produced and positive test results from finished peanut butter obtained onsite confirmed the presence of the outbreak strain. Being an ingredient-driven outbreak, many products distributed through various channels had the potential of being contaminated. As a result of the findings, recalls of peanut butter and peanut-containing foods were issued for products dated as far back as January 2007. In addition, the producing facility was directed to stop production and distribution of all products.^[3]
  • C jejuni
  • Yersinia enterocolitica
  • E coli - Enterohemorrhagic O157:H7, enterotoxigenic, enteroadherent, enteroinvasive
  • V cholera
  • Aeromonas
  • B cereus
  • C difficile
    • Clostridium difficile, often referred to as “C diff” is a gram-positive, spore-forming, toxin-producing bacillus that typically affects patients receiving antibiotic treatment, especially broad-spectrum ones (eg, cephalosporins, clindamycin, fluoroquinolones). Clinical symptoms of C difficile infection include watery diarrhea, fever, nausea, loss of appetite, and abdominal pain or tenderness. Complications that may result from infection include pseudomembranous colitis, toxic megacolon, perforations of the colon, sepsis, and even death, although it is rare. In some cases, infection resolves within 2-3 days of discontinuing the offending antibiotic. However, there are cases that require a full course of an appropriate antibiotic; several antibiotics are effective against C difficile. Severe cases may require surgery to remove the infected portion of the intestine.
    • Incidence and severity have increased during recent years due to the emergence of a more virulent epidemic strain. Elderly individuals are more commonly affected; however, infection may occur at any age and over the last few years its appearance in populations considered low risk has increased (ie, healthy outpatients, children, and people with no recent history of taking antibiotics). Host susceptibility is greater in hospitalized persons and those with underlying medical conditions. The bacterium is shed in feces and can be acquired from contact with contaminated surfaces, devices, or hands; it is considered to be a healthcare-associated infection. The use and application of evidence-based management and prevention strategies are important factors in the collaboration to reduce incidence of C difficile. New treatment strategies are currently under study. Clostridium perfringens
  • Listeria
  • M avium-intracellulare (MAI), immunocompromised
  • Providencia
  • V parahaemolyticus
  • V vulnificus
• Parasitic (10-15%)

  • Giardia
    • Giardia lamblia (also called Giardia intestinalis), a flagellate protozoan parasite, lives primarily in the upper part of the small intestine of an organism. Some infected individuals present with symptoms including diarrhea, bloating, greasy stools that tend to float, abdominal cramps, nausea/vomiting, and dehydration, while others may be asymptomatic. The average incubation period is 7-10 days, and symptoms may persist for 1-2 weeks. Most infections occur in children aged 1-9 years, but predominantly in those younger than 5 years. It is also seen in adults aged 25-44 years.
    • Infected persons may excrete cysts intermittently, making it difficult to diagnose. Several stool samples should be collected on various days and enzyme-linked immunosorbent assay (ELISA) or direct fluorescent antibody methods are usually performed to identify the parasite.
    • Transmission occurs from person to person or even from animal to person via fecal-oral route, through the ingestion of contaminated water. For example, it can be acquired from drinking downstream where a cow or other animal(s) may have contaminated the water. Risk of becoming infected is higher for travelers around the world, persons participating in outdoor activities/recreational water facilities, and those who consume unfiltered/untreated water (ie, hikers, campers).
    • The majority of cases are observed during the months of June to October, coinciding with the months of increased travel and outdoor/recreational water activities. There is increased risk in daycare centers and for close contacts of infected persons as well. Giardiasis occurs worldwide, with higher prevalence in areas where there is poor hygiene and sanitation. However, it is the most common intestinal parasitic disease in the United States, with an excess of 19,000 infections reported each year.
    • It has 2 stages, cyst and trophozoite. Both forms are passed in feces; however, the cyst is the infective stage and the one that can survive outside of a host and in the environment for weeks or months. It has moderate tolerance to chlorine and is capable of living in cold water for significant periods. Individuals infected with Giardia may shed 1 to 10 billion cysts daily, while the infectious dose is approximately 10 cysts, sometimes even as little as 1 or 2.
  • Amebiasis
  • Cryptosporidium
  • Cyclospora
• Food-borne toxigenic diarrhea

  • Preformed toxin -S aureus, B cereus
  • Postcolonization -V cholera, C perfringens, enterotoxigenic E coli, Aeromonas
• Shellfish poisoning and poisoning from other marine animals

  • Paralytic shellfish poisoning (PSP) - Saxitoxin
  • Neurologic shellfish poisoning (NSP) - Brevetoxin
  • Diarrheal shellfish poisoning (DSP) - Okadaic acid
  • Amnesic shellfish poisoning - Domoic acid
  • Ciguatera (ciguatoxins)
  • Scombroid (conversion of histidine to histamine)
• Drug-associated diarrhea

  • Antibiotics, due to alteration of normal flora
  • Laxatives, including magnesium-containing antacids
  • Colchicine
  • Quinidine
  • Cholinergics
  • Sorbitol
• Pseudomembranous colitis

  • Overgrowth of C difficile
  • Positive C difficile assay findings
• Other causes

  • Unknown agents, especially in developing countries
  • Ischemic colitis
  • Ulcerative colitis
  • Crohn disease
  • Carcinoid tumor or vasoactive intestinal peptide tumor (VIPoma)
  • AIDS
  • Dumping or short bowel syndrome
  • Radiation or chemotherapy