Snapshot A 2-year-old girl presents to her pediatrician with 1 week of low-grade fevers, initially watery diarrhea which became bloody today, and abdominal pain. Her parents report that when they saw some blood in the diarrhea, they were alarmed and decided to bring her in. On physical exam, the girl has sunken eyes and dry mucous membranes. Her belly is tender to palpation in the right lower quadrant. A bedside abdominal ultrasound shows a normal appendix. A stool sample is sent for studies. Meanwhile, she is given supportive care for treatment. Introduction Classification Yersinia enterocolitica a nonmotile, gram-negative, facultative intracellular bacillus non-lactose fermenting, oxidase negative, and does not produce H2S requires iron as an essential growth factor transmitted via ingestion of contaminated foods unpasteurized milk raw pork or seafood causes gastroenteritis and pseudoappendicitis Epidemiology demographics more common in infants and children risk factors day-care centers drinking or eating unpasteurized milk products iron overload chronic hemolysis hereditary hemochromatosis Pathogenesis the bacteria invade tissue proliferates in Peyer patches produces enterotoxin similar to E. coli heat-stable toxin Associated conditions erythema nodosum reactive arthritis Prognosis typically self-limited Presentation Symptoms acute diarrhea may be bloody abdominal pain may be in the right lower quadrant vomiting Physical exam low-grade fever tenderness to palpation of the abdomen Imaging Abdominal computed tomography (CT) indication suspected appendicitis findings normal appendix Studies Labs stool studies white blood cells culture Making the diagnosis based on clinical presentation Differential Acute appendicitis distinguishing factor ultrasound or CT shows enlarged appendix Treatment Management approach mainstay of treatment is supportive care antibiotics can be used in severe cases or immunocompromised patients Conservative supportive care indication all patients modalities hydration Medical aminoglycosides indication first-line for those who need treatment cephalosporins indication second-line trimethoprim-sulfamethoxazole indication second-line Complications Mesenteric vessel thrombosis and necrotic bowel Intussusception