442 THE SALMONELLA GROUP 



The method will be the same as for the isolation of the paratyphoid B 

 bacillus, viz. : preliminary enrichment in dulcite peptone water with sub- 

 sequent plating on neutral-red-lactose agar or Conradi-Drigalski's medium. 

 Suspicious colonies will then be examined as regards their biological pro- 

 perties fermentation reactions and production of indol. The identification 

 of the organism must finally rest upon a study of its reaction with known 

 serums. The impossibility of distinguishing it from the paratyphoid B 

 bacillus except by an investigation of absorption tests must be emphasized. 

 If specific serums be not available the bacillus must be inoculated into a 

 rabbit by the method described at p. 435, and the serum of the rabbit used for 

 agglutination and absorption tests. 



3. BACILLUS ENTERITIDIS GAERTNER. 



The gaertner bacillus was isolated by Gaertner at Frankenhausen 

 in 1888 from some meat which was suspected to have been the cause 

 of an epidemic of " food-poisoning " (p. 438) and also from the spleen of the 

 patient who died as a result of the infection. 



As a cause of " food -poisoning " the gaertner bacillus seems to be less common 

 than the aertrycke bacillus, but epidemics attributed to it have been recorded by 

 van Ermengem at Morseele, Brussels and Gand, by M'Weeney at Limerick and by 

 other observers ; while Bain bridge mentions eleven epidemics in which Gaertner'^ 

 bacillus was identified. In most of the cases in which the origin of the incriminated 

 food was traced, it was found to have been derived from animals which were ill at 

 the time of slaughter. 



Apart from epidemics of food poisoning the organism has rarely been recorded 

 in man four times by Morgan in cases of summer diarrhoea and once by Savage in 

 a case of enteric fever. 



The gaertner bacillus seems to cause an epizootic disease among animals. Such 

 epizootics have been recorded in rats and rabbits (Boycott, Dunbar, Bainbridge) 

 and in guinea-pigs (Bainbridge and O'Brien). 



According to Uhlenhuth Gaertner' s bacillus is a normal inhabitant of the rat's 

 intestine. 



In healthy cattle Gaertner's bacillus would appear to be of very uncommon 

 occurrence ; Sobernheim isolated it only twice from a very large number of such 

 animals, and Savage, Miiller and others have failed to detect it under similar 

 conditions. 



In sick cattle the organism has been isolated from calves suffering from diarrhoea, 

 from cows in cases of post partum sepsis, and from young calves in which possibly 

 infection took place through the umbilical cord. 



Savage has recently recorded finding it in a sausage. 



Boycott has described a spontaneous methsemoglobinsemia in rats due to infection 

 with the gaertner bacillus. 



The relation of the gaertner bacillus to other members of the paratyphoid 

 group is considered in Chap. XXV. 



SECTION I. EXPERIMENTAL INOCULATION. 



Recently isolated strains of Gaertner's bacillus are highly virulent to guinea- 

 pigs, rabbits and mice on sub-cutaneous and especially on intra-peritoneal 

 inoculation (^i^ mg. of a moist culture). Post mortem examination shows 

 hypersemia of the lungs, spleen, supra-renal capsules, etc. : in many cases 

 small areas of necrosis are seen in the liver. 



To infect animals by feeding them with cultures of the bacillus large 

 quantities of material have to be used : the young of a species are generally 

 more susceptible to this mode of infection than adults of the same species. 



Feeding experiments. Mice fed on the muscles, spleen, liver, etc. of the 



