wayson stain wayson stain the wayson stain is a basic fuchsin-methylene blue, ethyl alcohol-phenol microscopic staining procedure. it was originally a modified methylene blue stain used for diagnosing bubonic plague. with this stain, yersinia pestis appears purple with a characteristic safety-pin appearance, which is due to the presence of a central vacuole. blood smear taken from a patient with bubonic plague. note the safety pin appearance of yersinia pestis. magnification ×1000. wayson stain. wayson stain is used along with the giemsa and wright's stains to rapidly detect potential biowarfare attacks. it has also been investigated as a possible cheaper and faster way to detect melioidosis. it is a useful alternative to the gram or loeffler's methylene blue stains, especially for detecting yersinia enterocolitica which is often found in contaminated food.