CHAPTER X. 



DETECTION OF PATHOGENIC BACTERIA IN WATER AND MILK 



SUPPLIES. 



EXERCISE CXIV. EXAMINATION OF WATER FOR PATHOGENIC BACTERIA. 



BACILLUS TYPHOSUS. In the examination of water it is best to concentrate the 

 bacteria by filtering a large amount of the water through a Berkefeld filter and use the 

 slime on the filter to make the plates. 



a. Parietti's method, see CIX. 



6. Hiss' method. Make plate cultures and incubate at 38 C. for 18 hours. Inocu- 

 late suspicious colonies into Hiss' tube medium, fermentation tube, milk and make indol 

 test. Also try Widal reaction. 



c. Animal Inoculation. (Michigan method). 



1) Inoculate suspected water into bouillon tubes or flasks, and incubate at 38 C. 



2) Twenty-four to forty-eight hours later inoculate one cc. into the peritoneal cavity 

 of a white rat. 



3) If animal recovers B. typhosus is not present. If animal dies hold autopsy and 

 isolate and study organism causing death. 



MICROSPIRA COMMA. 



a. If there is reason to believe that the spirilla are very numerous gelatin plate cul- 

 tures can be made directly from the water, and the suspicious colonies worked up. 



l>. Ordinarily the organisms are very sparse and large quantities must be used, 100- 

 1000 cc. are placed in flasks aud 1% of peptone and 0.5% salt are added, the fluid made 

 alkaline and incubated at 38 C. for 6-24 hours. Then gelatin plate cultures are made from 

 the upper layers and the suspicious colonies worked up as above. 



EXERCISE CXV. EXAHINATION OF HILK FOR PATHOGENIC BACTERIA. 



B. DIPHTHERIAE. 



Where B. diphtherias is suspected in milk, make a considerable number of streak 

 cultures on Loefflers's blood serum and incubate at 38 C. for 8-12 hours and examine 

 growth microscopically very carefully for B. diphtheria*-. 



BACTERIUM TUBERCULOSIS (Koch) Mig. 



Hammond's method of examining milk for B. Tuberculosis. See Sputum, CVII. 



Animal Inoculation. 



Concerning the transmission of material containing Bacteria in Mails, see Postal Guide, 1898 

 Ruling No. 82, p. 901. Part of which is as follows: "That the order of the Postmaster General of 

 June 1, 18!)li, forbidding the use of mails for the transmission of specimens of germs of cholera or 

 other diseased tissues, is hereby modified to this extent: "Specimens of diseased tissue may be 

 admitted to the mails for transmission to United States, State or municipal laboratories only when 

 inclosed in mailing packages constructed in accordance with the specifications hereinafter enumer- 

 ated. Upon the outside of every package shall be written or printed the words: 'Specimen for 

 Bacteriological examination.' No package containing diseased tissue shall be delivered to any rep- 

 resentative until a permit shall have first been issued by the Postmaster General, certifying that 

 said institution has been found to l>e entitled, in accordance with the requirements of this regula- 

 tion, to receive such specimens." 



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