TECHNIC OF BACTERIOLYTIC TESTS 365 



Bacteriolytic Test in vivo for the Identification of Bacteria Recovered 

 from Feces, Water-supplies, etc. This method is employed chiefly in 

 the identification of suspected cholera cultures. According to Citron, 

 in Germany, the Pfeiffer test, made with microorganisms obtained in 

 pure culture from suspected patients, is required for the official diagno- 

 sis of the first cases of cholera. 



As a rule, the agglutination test is first applied in making the diag- 

 nosis of a suspected microorganism, as the technic of this test is more 

 easily carried out. 



This bacteriolytic test may also be employed in the study of typhoid 

 and paratyphoid bacilli, although bacteriolysis of these microorganisms 

 is less complete than that observed with cholera, and agglutination 

 tests answer all practical requirements. 



The test consists in mixing varying dilutions of a known and highly 

 immune serum with a constant dose of unknown microorganisms, and 

 injecting the mixtures intraperitoneally into guinea-pigs. After twenty 

 minutes small amounts of exudate are withdrawn by means of fine capil- 

 lary pipets, and studied in hanging-drop preparations. In the presence 

 of a positive reaction the bacilli are observed to lose motility, become 

 swollen and coccoid in shape, and gradually form granules, ultimately 

 disappearing in complete solution. 



Preparing the Immune Serum. A highly immune serum is required. 

 This may readily be prepared by giving rabbits a series of intravenous 

 injections of a known culture, according to the technic described in the 

 chapter on Active Immunization of Animals. The official test in Ger- 

 many demands that the serum be of such strength that 0.0002 gram of 

 dried serum will suffice to disintegrate completely within one hour one 

 loopful (2 mg.) of an eighteen-hour-old culture of virulent cholera in 

 1 c.c. of nutrient bouillon when injected into the peritoneal cavity of a 

 guinea-pig. The Hygienic Laboratory 1 in Washington is prepared to 

 furnish board of health laboratories with a dried serum of high titer for 

 diagnostic purposes. 



In testing an immune serum to determine its bacteriolytic titer the 

 dose of microorganisms should not be larger than one loopful, so that if 

 any particular strain of cholera or typhoid is not sufficiently virulent, 

 necessitating the use of larger doses, the virulence should be increased 

 by passing the organism through guinea-pigs. 



Method of Testing the Virulence of a Culture. The unit of measure- 

 ment is a 2 millimeter platinum loop, which, when loaded, will usually 

 1 Personal communication from Dr. John F. Anderson. 



