Figure 1: Wright-Giemsa peripheral blood smear with bipolar staining of Y. pestis
Provided By: CDC (1993)

Identification Criteria ... continued

Stains and Smears

Other stains...

Wright-Giemsa

The presence of bipolar-staining bacterial cells in
these smears should trigger the suspicion of plague.

The Wright stain often reveals the bipolar staining
characteristics of Y. pestis, whereas the
Gram stain may not [See Figure 1].

The Wright-Giemsa stains are the most reliable for accurately highlighting the bipolar staining characteristics of these Gram-negative rods.

         Note: In patients with overwhelming sepsis, bipolar staining rods may be
                 detected in peripheral blood smears.

The Wayson stain is another polychromatic stain, that can be used instead of the Wright-Giemsa stain.