Hemorrhagic typhlocolitis associated with attaching and effacing Escherichia coli in common marmosets

We describe the necropsy results from three common marmosets presented during an outbreak of hemorrhagic diarrhea in a colony of 230 common marmosets (Callithrix jacchus). Necropsy revealed consistent hemorrhagic typhlocolitis and variable ileitis associated with gram-negative bacilli closely adherent to enterocytes. Electron microscopy revealed bacilli attached intimately to shallow cup-like projections of enterocyte apical membranes with loss of microvilli (attaching and effacing). Escherichia coli isolates from affected marmosets were serogroup O26 and were positive for the E. coli attaching and effacing locus and negative for shiga-like toxin I and II, heat-stable enterotoxins a and b, and heat-labile enterotoxin by DNA probe hybridization. Results of a Vero cell cytotoxicity assay confirmed that the E. coli isolates did not produce shiga-like toxin. The increased availability of diagnostic probes for specific virulence factors such as attaching and effacing E. coli should lead to a greater understanding of the frequency of E. coli as a cause of diarrhea in nonhuman primates.