Pathogenic strain
The E. coli F4 strain provided by the Laboratório de Microbiologia do Hospital Veterinário da Universidade Estadual de Santa Cruz (UESC) was used. The strain is maintained in brain and heart infusion broth (BHI; BD Difco, Franklin Lakes, NJ) + 20% glycerol, in an ultra-freezer at -80 °C, and reactivated in BHI broth, incubated at 37 °C for 24 h.