432 PATHOGENIC MICROORGANISMS 



ified at first, but eventually is rendered strongly alkaline and cleared 

 up, possibly by casein solution. On lactose whey is alkalined and 

 becomes strongly blue. 



Eventual differentiation in doubtful cases must be made by agglu- 

 tination. Infection with type B is not uncommon and far outstrips 

 that with type A in importance. 



Clinically, the diseases caused by the bacteria of this class may be 

 divided into two main groups. 



I. Those which fall into the category of meat poisoning, having a 

 sudden and violent onset of gastroenteric symptoms directly following 

 the ingestion of meat, and characterized by profound toxemia; and 



II. Those in which the disease simulates a mild form of typhoid fever, 

 differing from this only by the absence of the specific agglutination re- 

 action for typhoid bacilli. 



The differential diagnosis between the second type of case and 

 true typhoid fever may be extremely difficult. However, careful 

 studies by Lentz* and others have revealed certain differences which 

 though not conclusive are at least of some aid in determining the nature 

 of the disease. In contradistinction to true typhoid the temperature 

 reaction of this case may set in more abruptly and remain more 

 irregular throughout the disease. Gastric symptoms, vomiting, and 

 nausea are often more prominent than in typhoid fever and enlargement 

 of the spleen is less regularly present than in the latter. Owing to the 

 low mortality of paratyphoid fever (in 120 cases observed by Lentz 

 less than 4 per cent, and in many other smaller epidemics no deaths 

 have occurred), we have remained relatively ignorant concerning the 

 pathologic anatomy of the disease. Longcope ^ observed a case which 

 was fatal after two weeks of illness in which there was no enlargement of 

 Peyer's patches and no sign of even beginning ulceration. This seems to 

 have been the experience of most other observers who have found less 

 involvement of the lymphatics of the bowel than is found in typhoid 

 fever. During the disease the bacteria can often be cultivated from 

 the blood, and the serum of the patient may agglutinate specifically 

 paratyphoid strains. In this way the diagnosis can often be made. 

 Libmann ^ has isolated the organism from the fluid aspirated from the 

 gall bladder in a case operated on for cholecystitis. 



Most of these microorganisms possess pathogenicity for mice, guinea- 



^ Lentz, Klin. Jahrb. xiv, 1914. 



2 Longcope, Amer. Jour, of Med. Sciences, cxxiv, 1902. 



^Libmann, Jour, of Med. Res., viii, 1902. 



