Case 88 answer Acute gastroenteritis is an ailment that is very common among children. During the first 3 years of life, a child will likely experience about 1 to 3 acute diarrheal illnesses. Diarrhea is defined as an increase in fluidity and volume of feces. Nearly all diarrheal infections are transmitted via the fecal-oral route. Many bacterial etiologies are also food borne. When evaluating a child with diarrhea and/or vomiting, several important points and observations in the history and physical can help to assess severity and determine its etiology and pathogen involved. Information on the number, volume, and/or fluidity of stools and emesis should be obtained (1). However, this can be rather cumbersome if the number of episodes is large since recording the volume of each stool and emesis is unrealistic and not very helpful clinically, once the number of episodes exceeds 5 to 10. A history of fever, blood or mucus in the diarrhea, foul odor to the diarrhea, a large quantity of diarrhea or diarrhea for a prolonged duration are suggestive of a bacterial etiology. Diarrheal mucus is not something that is intuitive to most parents. The best question to ask is whether they have noticed any slimy, gooey, gelatinous, or mucous-like material in the diarrhea. The presence of mucus in the diarrhea is generally indicative of sheets of white blood cells in the diarrhea. The vomiting history should determine whether the vomitus is bilious or bloody (i.e., red or brown) and whether this is associated with abdominal pain. Parents will often convey that the vomitus contains mucus, but unlike the mucus in diarrhea, this is normal gastric mucus that is not helpful clinically. Other important historical items include: weight loss, dietary (intake) history, ill contacts and travel history. The physical exam should focus on signs of dehydration, conditions that may suggest an acute surgical condition and other systemic conditions which may cause these symptoms. The differential diagnosis of vomiting is extensive including systemic conditions such as meningitis, increased intracranial pressure, heart failure, pneumonia, urinary tract infection and many acute surgical conditions such as appendicitis, intussusception, midgut volvulus, etc. The differential diagnosis of diarrhea is more limited and is most often due to gastroenteritis. Many organisms can cause acute infectious diarrhea and vomiting. These include bacteria, viruses, and parasites. Bacterial etiologies include: Campylobacter, E. coli, Staph aureus, Salmonella, Shigella, Vibrio, Yersinia and a few others. Viral gastroenteritis is by far more common. Amebic and parasitic etiologies are not very common in the United States, but such cases are treatable, making the identification of the pathogen essential. Lab tests available include: CBC, stool Wright stain, stool culture, stool Rotazyme, serum electrolytes and glucose. In most instances, no laboratory studies are required. A CBC might raise the clinical suspicion of a bacterial etiology if a very high band count is present; however, this may also occur in viral etiologies, therefore it is not very helpful in most instances. A positive stool Wright stain identifies WBCs in the stool. This is suggestive of a bacterial etiology (similar to the history or observation of mucus in the stool), but since it is unable to determine the specific pathogen, it does not help clinicians in determining whether antibiotics are indicated. Thus, in most instances of gastroenteritis, a Wright stain is not helpful. A stool culture can be obtained by swabbing a diarrhea sample or by inserting a swab into the rectum, then rotating it to obtain organisms from the rectal mucosal surface. This latter method is called a rectal swab and it has a higher yield for identifying enteric pathogens, which are more likely to be found on the rectal mucosal surface than in the diarrhea itself. Thus, if a stool culture is to be obtained, it should be done via a rectal swab. A stool Rotazyme is a rapid test which identifies the presence of rotavirus in the diarrhea. A positive Rotazyme negates the need for a stool culture and antibiotic therapy. Serum electrolytes and glucose may be helpful in determining the degree of electrolyte imbalance, metabolic acidosis and hypoglycemia.
Posted on: Mon, 06 Oct 2014 20:58:36 +0000
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