g STUDY AND IDENTIFICATION OF BACTERIA 



B. cholerae gallinarum and B. suisepticus are approximately similar in size and 

 cultural requirements to B. pestis. The oval bacillus with bipolar staining in smears 

 from tissues is very characteristic for both of them. Another name for swine plague 

 (B. suisepticus) is infectious pneumonia of swine. The organism is chiefly found in 

 the lungs. 



Where the plague bacilli are found chiefly in the glands, we have 

 bubonic plague; when in lungs, pneumonic plague; when localized in 

 the skin and subcutaneous tissue, the cellulo-cutaneous; and when as a 

 septicaemia, septicaemic plague. An intestinal type is recognized by 



FIG. 30. Colonies of plague bacilli forty-eight hours old. (Kolle and Wassermann.) 



some authors. It must be remembered that in all forms of plague the 

 lymphatic glands show hemorrhagic oedema; it is in bubonic plague, 

 however, that the areas of necrosis with periglandular oedema are 

 prominent. Where the symptoms are slight, mainly buboes, the term 

 pestis minor is sometimes used; the typical disease being termed pestis 

 major. In pneumonic plague we have a bronchopneumonia. 



In smears from material from buboes, from sputum, or in blood smears, as well 

 as from blood or spleen smears from experimental animals, we obtain the typical 

 morphology of a coccobacillus (1.5X0.5^) with very characteristic bipolar staining; 

 there being an intermediate, unstained area. Very characteristic also is the appear- 

 ance in these smears of degenerate types which stain feebly and show coccoid and 

 inflated oval types. The presence of these involution forms associated with typical 

 bacilli is almost diagnostic for one with experience. Inoculating tubes of plain agar 

 and 3% salt agar with this same material, we obtain in plain agar cultures organisms 

 which are typically small, fairly slender rods, which do not stain characteristically 

 at each end and are not oval. The smear obtained from the salt agar presents most 

 remarkable involution forms coccoid; root-shaped, sausage-shaped forms, ranging 



