SIGNIFICANCE OP COLON" COUNT IN MILK. 



Table 3. — Nature of colon-aerogenes contamination from the atmosphere (20 liters of air 

 drawn through 20 cubic centimeters of sterile milk). 





Examination of milk. 



Location of air. 



Fresh. 



After 24 hours at 70° F. (21.1° C). 





Colon 

 count. 1 



B. coli. 



B. aero- 

 genes. 



Colon 

 count. 1 



B. coli. 



B. aero- 

 genes. 







 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 2,100 

 

 

 200 

 



Per cent. 

 

 

 



Per cent. 

 

 

 



36,000 



140,000 



18,000,000 











5,000 



4,000,000 



1,700,000 



27, 000 







230.000,000 



205, 000, 000 



680, 000 



230, 000 



12,800,000 



12,700,000 







14,000,000 







6,700,000 



7,500,000 



60,000 



Per cent. 

 91 

 93 

 98 



Per cent. 

 9 



Do 



7 





2 







Do • 





















92 



100 







100 













8 















100 



Do 









Do 









 

 

 83 

 

 8 



100 



Do 







100 



Do 







100 









17 



Do 







100 









92 



Do 









Do 







100 







100 







Do 









 

 



100 



Do 







100 



100 



Do 



100 











i means none in 1/100 of a cubic centimeter of milk. 



It is of further interest to note that after enrichment in sterile milk 

 the majority of samples contained organisms mostly of the B. aero- 

 genes type, although in a few there was a large proportion of the 

 B. coli type. It is not surprising that organisms of the B. coli type 

 can be found in barn air, for they are present in large numbers in 

 fresh cow feces, and probably actually multiply as the feces become 

 dry. Evidence of this is furnished in Table 4, in which a composite 

 sample of feces from 4 cows was examined when fresh, and again 

 after 2, 10, and 14 days. The colon count is given per gram on both 

 the dry and the wet basis. The calculations of the count on a dry basis 

 show that there was an increase of from approximately 600,000 per 

 gram when fresh to approximately 93,000,000 per gram when air- 

 dried for 14 days. At the end of that time the organisms were still 

 sufficiently active to grow readily on litmus-lactose-asparagin agar. 

 It is easy to understand, therefore, how milk produced under clean 

 conditions may become contaminated with organisms of the B. coli 

 type. Contamination by this means, however, is not serious from 

 the standpoint of numbers introduced, because the small numbers that 

 enter from the air are greatly diluted in the milk. 



Table 4. — Direct increase of colon count in dried cow feces. 



Number of 

 days dried 



at 70° F. 



(21.1° C). 



Moisture. 



Colon 

 count, wet. 



Colon 

 count, dry. 



(fresh)... 

 2 



Per cent. 



84.5 



79.0 



6.3 



5.0 



Per gram. 



320, 000 



1, 500, 000 



49, 000, 000 



89, 000, 000 



Per gram. 

 590, 000 

 2, 685, 000 

 51,940,000 

 93,450.000 



10 



14 





