The Morphology of Bacterium tularense.

Divergent views exist concerning the morphology of Bacterium tularense. McCoy and Chapin's (1912) original description depicted an apparently immotile, small, questionably encapsulated, pleomorphic organism occasionally presenting enlarged, irregular, and apparent involution fonns; sometimes with predominant large globular forms. Ohara, Kobayashi, and Kudo (1935) claimed to have demonstrated flagella on both Japanese and American strains, stated that motility was observed repeatedly, and described clubbed, comma-shaped, dumbbell, and triangular forms. They further stated, "The more virulent is the bacterium, the greater is the pleomorphism"; also, "Virulence, pleomorphism, and motion are closely related and vary together." Galli-Valerio (1938), after working with cultures isolated by Drbohlav in Czechoslovakia, stated that both coccoid and bacillary forms were absolutely immotile and that no flagella were demonstrable by the Casares-Gil stain. He also failed to find any enlarged, elongated, filamentous, or involution forms. Most European language reports and textbooks omit all reference to flagella, state that the bacterium is nonmotile, present inadequate descriptions of the extraordinary pleomorphism, give scant mention to encapsulation except as an occasional finding in tissues or in tissue smears, and classify the organism among either Pasteurella or Brucella. Since the most extensive studies on morphology were conducted by Ohara and his associates, we reviewed thoroughly the Japanese literature. Ota (1936) states that Kudo and Kobayashi, working in Ohara's laboratory, first demonstrated a single polar flagellum in 1934, using the silver deposition method of Nishigawa and Sugahara (apparently the same as the Saisawa-Sugawara method mentioned by Ohara). They also observed capsules. Ota confirmed this work. He demonstrated flagella also with Victoria blue (4R), Burri's India ink method, and by his own modification of Benian's Congo red method. In his experience the methods of Loeffler, Benian, Zettnow, Inouye, Yokota, and Uyeno either failed entirely or showed few poorly stained flagella. Under dark-field illumination, "Refractile flagella were demonstrated." With regard to motility, "I found some actively motile, definitely changing their position." Capsules were well demonstrated by Ota's modification of Benian's method, mercurochrome negative staining, and by Gin's India-ink carbol-thionine method. The methods of Johne, Wadsworth, Hiss, Welch, and Friedlander were said to stain them poorly or not at all. Ota stained Bacterium tutarense and Yato-byo bacteria, also their flagella, in tissues with the Levaditi method. Successful preparations were made from human lymph node and skin, guinea pig spleen, and rabbit liver.