THE PARATYPHOID B. BACILLUS 433 



In Germany on the other hand " paratyphoid bacilli " i.e. paratyphoid B and 

 aertrycke have been isolated from the blood, stools and urine of healthy persons 

 (Conradi, Prigge and Sachs-Miike, Gaethgens) ; they have been found in enteric 

 fever patients, convalescents and contacts, and have been isolated also from persons 

 suffering from other diseases (Conradi). 



Distribution of the bacillus outside the body. Bainbridge failed to detect the 

 paratyphoid B. bacillus in the excreta of 50 healthy pigs. In Germany the organism 

 is said to have been isolated from sausages (Hiibener, Rommeler), milk, meat, etc. 

 (p. 438). Bainbridge however has examined a number of these so-called paratyphoid 

 B bacilli and finds that the strains submitted to him fall into two groups, viz. : 



1. Bacilli of the aertrycke type which were all obtained from food or from cases 

 of food- poisoning. 



2. Bacilli of the paratyphoid B type which were all derived from cases of para- 

 typhoid fever and paratyphoid carriers. 



Bainbridge therefore is of opinion that the normal habitat of the paratyphoid 

 B bacillus is the human alimentary canal and bile passages, and that its distribution 

 is limited to those situations. 



SECTION I. EXPERIMENTAL INOCULATION. 



The pathogenicity of strains of the paratyphoid B. bacillus is typically 

 of a high order (Boycott). Using guinea-pigs weighing 250 grams and broth 

 cultures incubated at 37 C. for 20 hours Boycott found that the inocula- 

 tion of 1 c.c. beneath the skin led to death in 18-40 hours, and that O'l c.c. 

 intra-peritoneally was followed by death in less than 18 hours. 



Feeding experiments were negative (Boycott). 



SECTION II. MORPHOLOGY. 



1. Microscopical appearance. Staining reactions. The paratyphoid B 

 bacillus is indistinguishable as regards its appearance under the microscope 

 and in its staining reactions from the typhoid and paratyphoid A bacilli. 



It is a stout, motile cocco-bacillus tending to stain more deeply at the ends 

 than in the centre ; in culture especially on gelatin it sometimes grows out 

 into filamentous forms ; it stains with ordinary aniline dyes and is gram- 

 negative. 



2. Cultural characteristics. In its cultural characteristics the paratyphoid 

 B bacillus approaches the colon bacillus. 



In broth it grows abundantly, often forming a pellicle on the surface and 

 occasionally giving rise to a faecal odour. 



On gelatin, isolated colonies are transparent at first but fairly rapidly 

 become opaque ; occasionally they retain the " iceberg " appearance. In 

 stroke culture the bacillus most frequently gives rise to a thick whitish layer 

 which becomes opaque and viscous as the culture ages. 



On potato the growth generally resembles that of the colon bacillus a 

 thick, brown viscous layer ; a glazed appearance is uncommon. 



On artichoke the culture is green in 2 or 3 days. 



Milk. Milk is not coagulated but becomes clear and about the second week 

 acquires a brownish tint. 



Litmus milk. First of all the medium becomes slightly acid, the litmus 

 turning red : but after about 3-7 days a secondary alkalinity develops, the 

 colour of the litmus reverting to blue. 



Litmus whey. In the first few days a small amount of acid is formed 

 turning the litmus red, afterwards the blue colour reappears. 



2E 



