Superimposed Infectious Colitis in Crohn's Disease

The differential diagnosis for an acute Crohn's flare should include enteric infection, a challenging yet critical distinction to make when determining appropriate therapy. Since both present similarly, identification of an enteric infection should be performed with comprehensive stool microbial testing. In the setting of moderate-to-severe disease, patients on biologic therapy may be more prone to infectious complications. We present a patient with chronic Crohn's disease with an unusual, previously undetected enteric infection due to Plesiomonas shigelloides. Once identified, appropriate antibiotic treatment led to resolution of the patient's acute symptomatology. This is the first reported case of P. shigelloides infection in Crohn's disease.