[Code of Federal Regulations]
[Title 9, Volume 1]
[Revised as of January 1, 2001]
From the U.S. Government Printing Office via GPO Access
[CITE: 9CFR113.25]

[Page 561-562]
 
                  TITLE 9--ANIMALS AND ANIMAL PRODUCTS
 
  CHAPTER I--ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF 
                               AGRICULTURE
 
PART 113--STANDARD REQUIREMENTS--Table of Contents
 
Sec. 113.25  Culture media for detection of bacteria and fungi.

    (a) Ingredients for which standards are prescribed in the United 
States Pharmacopeia, or elsewhere in this part, shall conform to such 
standards. In lieu of preparing the media from the individual 
ingredients, they may be made from dehydrated mixtures which, when 
rehydrated with purified water, have the same or equivalent composition 
as such media and have growth-promoting buffering, and oxygen tension-
controlling properties equal to or better than such media. The formulas 
for the composition of the culture media prescribed in Secs. 113.26 and 
113.27 are set forth in the United States Pharmacopeia, 19th Edition.
    (b) The licensee shall test each quantity of medium prepared at one 
time from individual ingredients and the first quantity prepared from 
each lot of commercial dehydrated medium for growth-promoting qualities. 
If any portion of a lot of commercial dehydrated medium is held for 90 
days or longer after being so tested, it shall be retested before use. 
Two or more strains of micro-organisms that are exacting in their 
nutritive requirements shall be used. More than one dilution shall be 
used to demonstrate the adequacy of the medium to support the growth of 
a minimum number of micro-organisms.
    (c) The sterility of the medium shall be confirmed by incubating an 
adequate number of test vessels and examining each for growth. 
Additional control may be used by incubation of representative 
uninoculated test vessels for the required incubation period during each 
test.
    (d) A determination shall be made by the licensee for each 
biological product of the ratio of inoculum to medium which shall result 
in sufficient dilution of such product to prevent bacteriostatic and 
fungistatic activity.

[[Page 562]]

The determination may be made by tests on a representative biological 
product for each group of comparable products containing identical 
preservatives at equal or lower concentrations. Inhibitors or 
neutralizers of preservatives, approved by the Administrator, may be 
considered in determining the proper ratio.

[35 FR 16039, Oct. 13, 1970, as amended at 37 FR 2430, Feb. 1, 1972; 41 
FR 27715, July 6, 1976; 56 FR 66784, Dec. 26, 1991]