EXAMINATION OF FLUIDS AND SOLIDS 183 



EXAMINATION OF EGGS 



When laid, eggs contain a few bacteria; if the shells have no cracks or breaks 

 in them and are free of macroscopic particles of dirt and if such eggs are collected 

 within several hours after they have been laid and immediately stored in clean, 

 dry containers at about i5C., the eggs remain "fresh" for many weeks with 

 slight, if any, multiplication of contained bacteria. 



Bacteria rapidly increase in cracked eggs and those exposed to a temperature 

 of 30C. to 40C. 



Market eggs, shown by candling, chemical examination and diet tests, to be 

 palatable and nutritious, yield 20,000 to 200,000 colonies per gram when cultured 

 a small portion of which are colon bacilli. 



Eggs in the shell that show more than 1000 colonies per gram are not accept- 

 able as food. . 



Frozen eggs and desiccated eggs (either whites, yolks or whole eggs) always 

 show a relatively more abundant flora than eggs in the shell. 



Frozen and desiccated eggs may be considered acceptable when the cultural 

 test shows less than 2,000,000 colonies per gram, not more than 0.02 per cent, of 

 which are colon bacilli. When the percentage of colon bacilli is considerably 

 greater or when the total count is above 20,000,000 colonies per cubic centi- 

 meter, the eggs have been handled, canned or stored in a manner that makes 

 them dangerous foodstuff and when the count is above 20,000,000 in addition 

 to being dangerous to health, they have been robbed of a considerable portion 

 of their nutritive value. 



These figures and conclusions are based on a resume of the extensive original 

 investigations of R . C. Rosenberger. 



TECHNIQUE FOR EXAMINATION OF EGGS IN SHELL 



1. Wash the eggs in 5 per cent, phenol solution at 5oC. by gently sponging 

 with cotton. 



2. Rinse in sterile water. 



3. Break shell with sterile spatula and empty contents into wide-mouthed, 

 sterile, weighed Erlenmeyer flask. 



4. Determine weight of egg or eggs in flask and add an equal volume of 

 sterile water, shake until homogenized. 



5. Put i.o Gm. in flask and mix with 499 Gm. of sterile water (i : 1000 di- 

 lution). 



6. Mix i cc. of the i : 1000 dilution with 9 cc. of sterile water and plates of 

 plain agar and litmus lactose agar with the following quantities: o.i cc., o.2cc., 

 0.5 cc., 0.7 cc. and i.o cc.; also plant o.i cc., 0.5 cc. and i.o cc. in fermentation 

 tubes containing litmus lactose broth. 



Incubate at 37C. for 3 days and inspect each day. Subculture representa- 

 tive red colonies that appear on litmus agar and make differential tests for iden- 

 tification of colon bacillus. 



