Hematopoietic neoplasms accompanied by severe enterocolitis due to Aeromonas species

Aeromonas species are known to be a cause of diarrhea and acute enterocolitis. However, only a few cases have been reported and the pathophysiology of Aeromonas infection has not as yet been clarified. We experienced 2 cases developing severe enterocolitis during the course of hematological malignancies, specifically multiple myeloma and diffuse large B-cell lymphoma. Both patients presented with watery diarrhea that persisted for more than a week, followed by bloody diarrhea. Total colon endoscopy showed multiple ulcers on the mucosa from the sigmoid colon to the rectum, and biopsies from the ulcer revealed infiltration of neutrophils and eosinophils in the mucosa and submucosa. Aeromonas hydrophila and Aeromonas sobria were isolated from stool cultures, respectively. Treatment with oral ciprofloxacin was effective in both patients and clinical symptoms showed significant improvement. These cases raise the possibility of Aeromonas infection as a cause of severe enterocolitis and the importance of making a correct differential diagnosis and appropriate antibiotic treatment in immunocompromised patients including those with hematological malignancies.