Watery Diarrhea Is Not Always Clostridioides difficile: A Case Report of Aeromonas hydrophila Gastroenteritis

Aeromonas species can cause acute gastroenteritis but are much less commonly observed in the hospital setting than other bacteria. Most cases of Aeromonas hydrophila gastroenteritis reported in the literature have occurred in pediatric, elderly, and/or immunocompromised patients. We present a case of subacute watery diarrhea due to A. hydrophila infection in an otherwise healthy 48-year-old female patient with prior abdominal surgeries and recent hospitalization for a catheter-associated urinary tract infection (CAUTI) for which she received antibiotics. The patient presented with 10 days of increasingly frequent non-bloody, watery, foul-smelling diarrhea as well as decreased oral intake, cramping bilateral upper abdominal pain, chills, and malaise. Initial diagnoses considered included Clostridioides difficile in the setting of CAUTI and antibiotic use, small intestinal bacterial overgrowth, dumping syndrome related to bariatric surgery, and malabsorption. A computed tomography scan of her abdomen/pelvis, admission labs, and flexible sigmoidoscopy showed no relevant findings. Stool cultures eventually returned positive for A. hydrophila. The case is an uncommon presentation of Aeromonas infection that could be easily missed while other diagnoses are pursued. Early treatment of Aeromonas infection can be crucial in preventing advanced forms of disease such as septicemia and necrotizing fasciitis.