220 BACTERIOLOGY FOR NURSES 



The reduction in mortality by the use of the serum is estimated at 

 about 20 per cent. 



Vaccines. Dysentery vaccines have been employed with mod- 

 erately good results. The fact that there are so many strains 

 lessens their value unless it is known to which group the invading 

 organisms belong. 



Bacteriological Diagnosis. Isolation from the feces is the sur- 

 est method of identifying the strain causing infection. The meth- 

 ods employed are exactly the same as those employed in typhoid 

 and paratyphoid infection except that crystal violet should be 

 omitted from the Conradi medium on account of the inhibitory 

 effect of the anilin dyes on many of the dysentery strains. After 

 isolation the organism should be tested with the specific agglu- 

 tinating serum and confirmatory evidence gained by growing it 

 on the different sugar media. 



