A 3-year-old boy who attends a child care center presents to his pediatrician with a 2-day history of bloody diarrhea with mucus. On physical examination, he is well hydrated and has mild abdominal tenderness. The pediatrician orders a stool culture for enteric pathogens and recommends supportive care including appropriate hydration and close follow-up. Forty-eight hours later, the stool culture is reported as positive for Shigella sonnei (Figure 179-1). Because the boy continued to have bloody diarrhea, the pediatrician treated the boy with a 5-day course of azithromycin and he recovered completely. Two stool cultures obtained after the completion of therapy were negative and the boy was able to resume child care.
Gastrointestinal infections frequently manifest as diarrhea (loose, watery stools), frequently with fever, vomiting, and abdominal pain. Although many of these infections are self-limited, these infections can be associated with intestinal and extra-intestinal manifestations and can lead to significant morbidity.
Worldwide, diarrheal illness is a leading cause of morbidity and mortality.
Diarrhea accounts for 2 to 4 million health care visits, 220,000 hospitalizations, and 300 to 400 deaths annually in the US.1
Diarrhea is the most common illness encountered by international travelers to developing countries.2
Acquisition of intestinal pathogens occurs through the fecal-oral route, from person-to-person contact or from contaminated food and water. Many pathogens can be spread by either person-to-person contact or from contaminated food and water.
Pathogens that are spread through person-to-person contact include Shigella spp Escherichia coli O157:H7, and most viral causes of diarrhea. These agents are commonly implicated in outbreaks in childcare centers.
Pathogens that are spread through contaminated food and water include Salmonella spp Campylobacter spp, enterotoxigenic E coli, and many viruses.
Enterotoxigenic E coli Salmonella Campylobacter, and Shigella are the most common causes of traveler’s diarrhea.
Pet reptiles are common sources of Salmonella infection. Transmission of this organism to household members, especially young infants, can occur in the absence of direct contact in household. Salmonella bacteremia and meningitis has occurred from transmission from pet lizards.
Common bacterial causes of gastroenteritis include Campylobacter spp, Salmonella spp, diarrheal-producing strains of E coli Shigella spp, and Yersinia spp.
Virulent traits of these agents include enterotoxins and cytotoxins that promote aggregation and invasiveness that result in clinical symptoms.
Antibiotic-associated colitis is due to toxin-producing strains of Clostridium difficile.
Common viral causes of diarrhea include rotavirus, enteric adenovirus, norovirus, and astrovirus.
Universal immunization of infants in the US with rotavirus vaccine has resulted in a dramatic decline in rotavirus illness requiring hospitalization.3
Viruses exert their diarrheal effect through selective destruction of absorptive cells in the mucosa, reduction of brush border enzymes, and alteration of the absorptive fluid balance in the gut.
Host factors also influence susceptibility to infection and colonization. Children with underlying immunodeficiencies and premature infants are more at risk for severe episodes of diarrhea and complications of diarrhea, leading to increased morbidity and mortality.
Extraintestinal manifestations of enteric pathogens result from direct local or remote spread of infection or are the result of immune-mediated mechanisms.
Child care attendance.
Immunodeficiency.
Prematurity.
Ingestion of undercooked food.
Exposure to animals and pets that may harbor infectious organisms like Salmonella.
Travel to developing countries.
Watery diarrhea is characteristic of infection with enteric viruses and enterotoxin-producing bacteria.
Dysentery—Stools containing blood and mucus can result from bacterial causes that invade the large intestine, such as Shigella infection.
Vomiting with minimal or no diarrhea—Can occur with viral causes as well as toxin-producing bacteria.
Mesenteric adenitis is often a feature of bacterial gastroenteritis. This can simulate appendicitis if the pain is in the right lower quadrant.
Disseminated infection and meningitis is a complication of Salmonella gastroenteritis and occurs mostly in young infants.
Disseminated disease can occur with any bacterial cause of gastroenteritis in immunocompromised hosts.
Extraintestinal immune mediated manifestations and the related pathogens include:
Erythema nodosum—Related to Salmonella spp, Campylobacter spp, and Yersinia spp.
Guillain Barre Syndrome—May follow Campylobacter jejuni infection.
Reactive arthritis—Related to Shigella Salmonella Yersinia, and Campylobacter infections.
Hemolytic uremic syndrome (HUS)—Most commonly related to Shiga-toxin producing E coli.
Seizures—Can be a feature of Shigella infection and may occur prior to the onset of diarrhea. These are benign and self-limited.
Most episodes of diarrhea are self-limited and testing is not warranted for most cases.
Stool should be examined for the presence of blood and mucus, which may serve as a clue as to the pathogen. In general, pathogens causing invasion, such as shiga-toxin producing E coli and some serotypes of Shigella, produce bloody diarrhea.
In general, stool cultures are indicated when stools contain blood or fecal leukocytes, when hemolytic uremic syndrome is suspected, during outbreaks, and in immunocompromised children.
Routine stool cultures in most laboratories test for Campylobacter Salmonella Shigella, and Yersinia species. Identification of E coli O157:H7 requires special assays, which should be used for cases of suspected hemolytic uremic syndrome.
Identification of toxin producing strains of C. difficile can be done using enzyme immunoassays or polymerase chain reaction techniques.
Stool antigen tests can be used to detect rotavirus infection.
When HUS is suspected, a renal panel and CBC are indicated. The finding of a microangiopathic hemolytic anemia, thrombocytopenia and renal dysfunction is consistent with HUS (see Chapter 69, Hemolytic Uremic Syndrome).
Other causes of diarrhea such as irritable bowel disease, toddler’s diarrhea, and inflammatory bowel disease need to be considered in the differential diagnosis. A thorough history and associated findings such as fever are helpful clinically. Stool studies help to rule out infectious etiologies when the diagnosis is not clear.
Toddler’s diarrhea (chronic nonspecific diarrhea of childhood) affects children from 6 months to 5 years of age. Children with toddler’s diarrhea will have 3 to 10 loose stools per day but continue to grow and gain weight normally. These children will grow out of this on their own without treatment.
Bacterial causes of gastroenteritis can cause an intense mesenteric adenitis and can mimic appendicitis. This is classically attributed to Yersinia infection, but can occur with other bacteria that cause gastroenteritis.
Careful attention to fluid and electrolyte status is of the utmost importance in all cases of diarrhea.
Oral rehydration therapy is preferred modality for the management of diarrhea in otherwise healthy children who have mild or moderate dehydration.4
Current oral rehydration therapies in the US, such as Pedialyte, Rehydralyte, Enfalyte, and CeraLyte-50 are glucose-electrolyte solutions that can be used in infants and children with mild to moderate dehydration.
Multiple studies, both in the US and in developing countries, have shown that early feeding of age-appropriate foods, including milk, to children with diarrhea after rehydration is associated with decreased stool output and reduction in duration of diarrhea.
Antimotility agents have not been shown to be effective in treating acute diarrhea in infants and children, and are associated with systemic toxic effects that may be exaggerated in infants and children; thus, their use is not recommended.
Probiotics, especially Lactobacillus rhamnosus GG, used early in the course of acute viral gastroenteritis, may reduce the duration of diarrhea by 1 day.5,6 SOR B
Probiotics may also prevent antibiotic-associated diarrhea.
There is no evidence to support probiotics in the prevention of infectious diarrhea or in the treatment of antibiotic-associated diarrhea.
Definite recommendations regarding the use of specific probiotics are lacking and await further clinical trials in infants and children.
Antimicrobial therapy for most cases of acute gastroenteritis is generally not of benefit. Antimicrobial therapy for acute gastroenteritis may be of benefit in specific cases:
Shigella infections—Therapy may be effective in shortening duration of diarrhea and hastening eradication of the organism and is recommended for patients with severe disease, dysentery, or underlying immunosuppressive conditions. Azithromycin, ciprofloxacin, or a parenteral third-generation cephalosporin may be used for treatment when required.7 SOR B
Campylobacter jejuni—Azithromycin and erythromycin shorten the duration of illness and excretion of organisms and prevent relapse when given early in gastrointestinal tract infection.8 SOR B
Non-typhi Salmonella infections in infants less than 3 months—Antimicrobial therapy is used in young infants to prevent dissemination of the organism, although the benefit of this practice is unproven. Treatment of Salmonella gastroenteritis in otherwise healthy children 3 months of age and older is not beneficial and not recommended.9 SOR C
Traveler’s diarrhea—Azithromycin is preferred for children who develop a diarrheal illness in a developing country.
C difficile infections—Metronidazole administered orally or parenterally is the first line treatment. Oral vancomycin is reserved for refractory cases.
Salmonella typhi—See Chapter 7, Global Health.
Cholera—See Chapter 7, Global Health.
Children with severe dehydration, complications of gastroenteritis, or with extra-intestinal manifestations may require hospitalization and/or referral with a pediatric gastroenterologist or infectious disease specialist.
Careful attention to public and personal hygienic practices is important in decreasing diarrheal illnesses.
Assuring clean water, food, and sanitation is essential in preventing diarrheal illness.
Careful hand hygienic practices are the most important personal measures that can be used to prevent transmission of diarrheal agents.
Breastfeeding decreases morbidity and mortality associated with diarrheal illness.
Proper food preparation is important in preventing contamination and transmission of infectious agents.
Pet reptiles should not be avoided in households where young children and immunocompromised individuals reside.9
A rotavirus vaccine should be given to all infants starting at 2 months of age; two vaccines are currently available for infants, and are safe and effective.10
Two S typhi vaccines are licensed for children traveling to countries where S typhi is endemic; a polysaccharide vaccine parenteral vaccine is available for children 2 years and older, and a live oral typhoid vaccine is available for children 6 years of age and older.9
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