History Acute diarrhea in developed countries is almost invariably a benign, self-limited condition, subsiding within a few days. The clinical presentation and course of illness depend on the etiology of the diarrhea and on the host. For example, rotavirus is more commonly associated with vomiting, dehydration, and a greater number of work days lost than nonrotavirus gastroenteritis. A prospective study conducted in the United States in 604 children aged 3-36 months in community settings before the introduction of rotavirus vaccine found that the highest incidence of acute diarrhea was in January and August, with an overall incidence of 2.21 episodes per person-year.[8] Close to 90% of episodes were acute (ie, lasting < 14 d, with a median duration of 2 d and a median of 6 stools per day). Diarrhea implies an increase in stool volume and diminished stool consistency. In children younger than 2 years, diarrhea is defined as daily stools with a volume greater than 10 mL/kg. In children older than 2 years, diarrhea is defined as daily stools with a weight greater than 200 g. In practice, this typically means loose-to-watery stools passed 3 or more times per day. Individual stool patterns widely vary; for example, breastfed children may normally have 5-6 stools per day. Flatulence associated with foul-smelling stools that float suggests fat malabsorption, which can be observed with infection with Giardia lamblia. Knowledge of the characteristics of consistency, color, volume, and frequency can be helpful in determining whether the source is from the small or large bowel. Table 1 outlines these characteristics and demonstrates that an index of suspicion can be easily generated for a specific set of organisms. Table 1: Associated systemic symptoms include the following: Some enteric infections commonly have systemic symptoms, whereas others less commonly are associated with systemic features. Table 2 outlines the frequency of some of these symptoms with particular organisms. It also outlines incubation periods and usual duration of symptoms of common organisms. Certain organisms (eg, C difficile, Giardia, Entamoeba species) may be associated with a protracted course. Table 2: Daycare considerations are as follows: Certain organisms are spread quickly in daycare. These organisms include rotavirus; astrovirus; calicivirus; and Campylobacter, Shigella, Giardia, and Cryptosporidium species. Increase in daycare usage has raised the incidence of rotavirus andCryptosporidium species. Food history can be helpful. Ingestion of raw or contaminated food is a common cause of infectious diarrhea. Organisms that cause food poisoning include the following: Dairy food -Campylobacter and Salmonella species Eggs -Salmonella species Meats -C perfringens and Aeromonas, Campylobacter, andSalmonella species Ground beef - Enterohemorrhagic E coli Poultry -Campylobacter species Pork -C perfringens, Y enterocolitica Seafood - Astrovirus and Aeromonas, Plesiomonas, and Vibriospecies Oysters - Calicivirus and Plesiomonas and Vibrio species Vegetables -Aeromonas species and C perfringens Water exposure can contribute to diarrhea. Water is a major reservoir for many organisms that cause diarrhea. Swimming pools have been associated with outbreaks of infection withShigella species; Aeromonas organisms are associated with exposure to the marine environment. Giardia, Cryptosporidium, and Entamoeba organisms are resistant to water chlorination; therefore, exposure to contaminated water should raise index of suspicion for these parasites. A history of camping suggests exposure to water sources contaminated withGiardia organisms. Travel history may indicate a cause for diarrhea. Enterotoxigenic E coli is the leading cause of traveler's diarrhea. Rotavirus and Shigella, Salmonella, and Campylobacter organisms are prevalent worldwide and need to be considered regardless of specific travel history. Risk of contracting diarrhea while traveling is, by far, highest for persons traveling to Africa. Travel to Central and South America and Eastern European countries is also associated with a relatively high risk of contracting diarrhea. Other organisms that are prevalent in particular parts of the world include the following: Nonspecific foreign travel history - Enterotoxigenic E coli andAeromonas, Giardia, Plesiomonas, Salmonella, and Shigellaspecies Underdeveloped tropical visit -C perfringens Travel to Africa -Entamoeba species, Vibrio cholerae Travel to South America and Central America -Entamoebaspecies, V cholerae, enterotoxigenic E coli Travel to Asia -V cholerae Travel to Australia -Yersinia species Travel to Canada -Yersinia species Travel to Europe -Yersinia species Travel to India -Entamoeba species, V cholerae Travel to Japan -Vibrio parahaemolyticus Travel to Mexico -Aeromonas, Entamoeba, Plesiomonas, andYersinia species New Guinea -Clostridium species Animal exposure can contribute to diarrhea. Exposure to young dogs or cats is associated with Campylobacterorganisms. Exposure to turtles is associated with Salmonella organisms. Certain medical conditions predispose patients to infection, including the following: C difficile - Hospitalization, antibiotic administration Plesiomonas species - Liver diseases or malignancy Salmonella species - Intestinal dysmotility, malnutrition, achlorhydria, hemolytic anemia (especially sickle cell disease), immunosuppression,malaria Rotavirus - Hospitalization Giardia species -Agammaglobulinemia, chronic pancreatitis, achlorhydria, cystic fibrosis Cryptosporidia species - Immunocompromised or immunosuppressed state PHYSICAL PRESENTATION: The following may be observed: Dehydration Dehydration is the principal cause of morbidity and mortality. Assess every patient with diarrhea for signs, symptoms, and severity. Lethargy, depressed consciousness, sunken anterior fontanel, dry mucous membranes, sunken eyes, lack of tears, poor skin turgor, and delayed capillary refill are obvious and important signs of dehydration. Table 3 below details dehydration severity and symptoms. Table 3: Failure to thrive and malnutrition Reduced muscle and fat mass or peripheral edema may be clues to the presence of carbohydrate, fat, and/or protein malabsorption. Giardia organisms can cause intermittent diarrhea and fat malabsorption. Abdominal pain Nonspecific nonfocal abdominal pain and cramping are common with some organisms. Pain usually does not increase with palpation. With focal abdominal pain worsened by palpation, rebound tenderness, or guarding, be alert for possible complications or for another noninfectious diagnosis. Borborygmi: Significant increases in peristaltic activity can cause an audible and/or palpable increase in bowel activity. Perianal erythema Frequent stools can cause perianal skin breakdown, particularly in young children. Secondary carbohydrate malabsorption often results in acidic stools. Secondary bile acid malabsorption can result in a severe diaper dermatitis that is often characterized as a "burn." Laboratory Studies The following may be noted in patients with diarrhea: In patients with diarrhea, a stool pH level of 5.5 or less or presence of reducing substances indicates carbohydrate intolerance, which is usually secondary to viral illness and transient in nature. Enteroinvasive infections of the large bowel cause leukocytes, predominantly neutrophils, to be shed into stool. Absence of fecal leukocytes does not eliminate the possibility of enteroinvasive organisms. However, presence of fecal leukocytes eliminates consideration of enterotoxigenic E coli, Vibriospecies, and viruses. Examine any exudates found in stool for leukocytes. Such exudates highly suggest colitis (80% positive predictive value). Colitis can be infectious, allergic, or part of inflammatory bowel disease (Crohn disease, ulcerative colitis). Many different culture mediums are used to isolate bacteria. Table 3 lists common bacteria and optimum culture mediums for their growth. A high index of suspicion is needed to choose the appropriate medium. With stool not cultured within 2 hours of collection, refrigerate at 4°C or place in a transport medium. Although stool cultures are useful when positive, yield is low.= Always culture stool for Salmonella, Shigella, and Campylobacter organisms and Y enterocolitica in the presence of clinical signs of colitis or if fecal leucocytes are found. Look for C difficile in persons with episodes of diarrhea characterized by colitis and/or blood in the stools. Remember that acute-onset diarrheal episodes associated with C difficile may also occur without a history of antibiotic use. Bloody diarrhea with a history of ground beef ingestion must raise suspicion for enterohemorrhagic E coli. If E coli is found in the stool, determine if the type of E coli is O157:H7. This type of E coli is the most common, but not only, cause of HUS. History of raw seafood ingestion or foreign travel should prompt additional screening for Vibrio and Plesiomonas species. Table 4: Culture mediums used to isolate bacteria include the following: Blood agar - All aerobic bacteria and yeast; detects cytochrome oxidase production MacConkey EMB agar - Inhibits gram-positive organisms; permits lactose fermentation XLD agar; HE agar - Inhibits gram-positive organisms and nonpathogenic GNB; permits lactose fermentation H2S production Skirrow agar - Selective for Campylobacter species SM agar - Selective for enterohemorrhagic E coli CIN agar - Selective for Y enterocolitica TCBS agar - Selective for Vibrio species CCFE agar - Selective for C difficile Rotavirus antigen can be identified by enzyme immunoassay and latex agglutination assay of the stool. The false-negative rate is approximately 50%, and false-positive results occur, particularly in the presence of blood in the stools. Adenovirus antigens can be detected by enzyme immunoassay. Only serotypes 40 and 41 are able to induce diarrhea. Examination of stools for ova and parasites is best for finding parasites. Perform stool examination every 3 days or every other day. The leukocyte count is usually not elevated in viral-mediated and toxin-mediated diarrhea. Leukocytosis is often but not constantly observed with enteroinvasive bacteria. Shigella organisms cause a marked bandemia with a variable total white blood cell count. At times, a protein-losing enteropathy can be found in patients with extensive inflammation in the course of enteroinvasive intestinal infections (eg,Salmonella species, enteroinvasive E coli). In these circumstances, low serum albumin levels and high fecal alpha1-antitrypsin levels can be found. Source
