The test for detection of Salmonella contamination provided in this section shall be conducted when such a test is prescribed in an applicable Standard Requirement or in the filed Outline of Production for the product.
- (a) Samples shall be collected from the bulk suspension before bacteriostatic or bactericidal agents have been added. When tissue culture products are to be tested, 1 ml of tissue extract used as the source of cells or 1 ml of the minced tissue per se shall be tested.
- (b) Five ml of the liquid vaccine suspension shall be used to inoculate each 100 ml of liquid broth medium (tryptose and either selenite F or tetrathionate). The inoculated media shall be incubated 18-24 hours at 35-37 °C.
- (c) Transfers shall be made to either MacConkey agar or Salmonella-Shigella agar, incubated for 18-24 hours and examined.
- (d) If no growth typical of Salmonella is noted, the plates shall be incubated an additional 18-24 hours and again examined.
- (e) If suspicious colonies are observed, further subculture on suitable media shall be made for positive identification. If Salmonella is found, the bulk suspension is unsatisfactory.
[38 FR 29888, Oct. 30, 1973]