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