Bacteriologic Methods 603 



frozen with liquid air and injecting animals with the thus liberated 

 intracellular toxin, seems to be no improvement upon others. 



Meyer and Bergell* prepared a serum by injecting horses with a 

 new typhoid toxin. After two years' treatment they were able to 

 demonstrate its value in curing infection in laboratory animals, 

 von Leydenf speaks in favorable terms of this serum. 



The typhoid immune (bacteriolytic) serum is specific, but its 

 action requires the presence of additional complementary substance, 

 and by itself it is useless. Indeed, it may do harm by causing the 

 formation of anti-immune bodies. 



So far no serum has been produced that is of any certain value in 

 therapeutics. 



Bacteriologic Diagnosis. — There are four bacteriologic methods 

 that may assist the clinician in completing the diagnosis of typhoid 

 fever. In the order of their general usefulness and practicability 

 these are: 



1. The Widal reaction of agglutination. 



2. The blood-culture. 



3. The isolation of the bacillus from the feces. 



4. The conjunctival and dermal reactions. 



Widal Reaction of Agglutination. — This very valuable adjunct to 

 our means of making the diagnosis of atypical and obscure cases of 

 typhoidal infection was discovered in 1896 when Widal and Grun- 

 baum,J working independently, observed that when blood-serum 

 from typhoid fever patients is added to cultures of the typhoid 

 bacillus a definite reactive phenomenon occurs. The phenomenon, 

 now familiarly known as the "Widal reaction," consists of complete 

 loss of the motion so characteristic of the typhoid bacillus, and the 

 collection of the micro-organisms into clusters or groups — agglutina- 

 tion. The bacteria frequently appear shrunken and partly dissolved. 



The technic of the test is outlined in the section upon Agglutination 

 iq.v.). For the use of the practising physician, commercial houses 

 now furnish various outfits known as " agglutometers," in which are 

 found such simple apparatus and directions as will enable those 

 inexpert in laboratory manipulations to arrive at fairly accurate 

 results. 



The Blood-culture. — The technic of this operation is simple. 

 The skin of the fold of the elbow is thoroughly cleansed, a fillet put 

 about the arm, and as the veins become prominent, a sterile hypo- 

 dermic needle is introduced into one and about 10 cc. of blood 

 drawn into a Keidel tube or into a syringe. Before clotting can take 

 place, this is discharged into a small flask containing 100 cc. of 

 bouillon, mixed, and stood away to incubate. After twenty-four 

 hours the bacilU can usually be found in pure culture. 



* "Med. Klinik," ill, No. 31, p. 917, Aug. 4, 1907. 

 t "Berl. klin. Wochenschrift," 1907, No. 18. 

 t "La Semaine Medicale," 1896, p. 293. 



