Acute invasive diarrhea in the pediatric patient

In acute invasive diarrhea, the pathogen penetrates the epithelial cells of the intestinal mucosa. Symptoms are produced by one or more of the following mechanisms: production of enterotoxins, increased synthesis of prostaglandins, and impaired reabsorption of fluids and electrolytes. The invasive process often results in dysentery, which is characterized by watery stools containing blood and mucus, accompanied by cramps, rectal burning, fever, and, sometimes, toxicity. Among the complications are bacteremia and toxic megacolon. Diagnosis is based on the patient's clinical condition and examination of stools. Microscopic examination of stools can rule out parasites and detect leukocytes, particularly polymorphonuclear leukocytes, a finding that suggests a bacterial origin for the disease. Because most patients are not severely dehydrated, rehydration is not the mainstay of treatment; in most cases, fluids can be replaced orally. Absorbents are ineffective, and antiperistaltic drugs should not be used routinely in children. Although often unnecessary in simple cases of invasive diarrhea, antimicrobials are useful when risk factors related to age, clinical condition, malnourishment, dehydration, or underlying disease are present. In such cases, antimicrobial therapy should begin when the clinical diagnosis has been made, to ensure the best clinical response.