Hematoxylin-eosin, Giemsa, and Gram stainings were performed by a standard method. For electron microscopy, bacteria
were grown in brucella broth containing 3% horse serum for 24 h,washed once with 5 volumes of 10% glycerol MOPS buffer and suspended in 5 volumes of saline.Samples were dried onto a collodion-carbon-coated grid. Shadowing was performed and samples were observed with a JEM-200CX (JEOL) transmission electron microscope as described