Growth Promotion and Inhibitory Properties of the Media
Test each batch of ready-prepared medium and each batch of medium prepared either from dehydrated medium or from ingredients. Verify suitable properties of relevant media as described in
Table 1.
Table 1. Growth Promoting, Inhibitory, and Indicative Properties of Media
Test/Medium |
Property |
Test Strains |
Test for bile-tolerant Gram-negative bacteria |
Enterobacteria Enrichment Broth Mossel |
Growth promoting |
E. coli |
|
|
P. aeruginosa |
|
Inhibitory |
S. aureus |
Violet Red Bile Glucose Agar |
Growth promoting + Indicative |
E. coli |
|
|
P. aeruginosa |
Test for Escherichia coli |
MacConkey Broth |
Growth promoting |
E. coli |
|
Inhibitory |
S. aureus |
MacConkey Agar |
Growth promoting + Indicative |
E. coli |
Test for Salmonella |
Rappaport Vassiliadis Salmonella Enrichment Broth |
Growth promoting |
Salmonella enterica ssp. enterica serotype typhimurium or |
|
|
Salmonella enterica ssp.enterica serotype abony |
|
Inhibitory |
S. aureus |
Xylose Lysine Deoxycholate Agar |
Growth promoting + Indicative |
Salmonella enterica ssp. enterica serotype typhimurium or |
|
|
Salmonella enterica ssp.enterica serotype abony |
|
Indicative |
E. coli |
Test for Pseudomonas aeruginosa |
Cetrimide Agar |
Growth promoting |
P. aeruginosa |
|
Inhibitory |
E. coli |
Test for Staphylococcus aureus |
Mannitol Salt Agar |
Growth promoting + Indicative |
S. aureus |
|
Inhibitory |
E. coli |
Test for Clostridia |
Reinforced Medium for Clostridia |
Growth promoting |
Cl. sporogenes |
Columbia Agar |
Growth promoting |
Cl. sporogenes |
Test for Candida albicans |
Sabouraud Dextrose Broth |
Growth promoting |
C. albicans |
Sabouraud Dextrose Agar |
Growth promoting + Indicative |
C. albicans |
Test for Growth-Promoting Properties, Liquid Media
Inoculate a portion of the appropriate medium with a small number (not more than 100 cfu) of the appropriate microorganism. Incubate at the specified temperature for not more than the shortest period of time specified in the test. Clearly visible growth of the microorganism comparable to that previously obtained with a previously tested and approved batch of medium occurs.
Test for Growth-Promoting Properties, Solid Media
Perform
Surface-Spread Method (see
Plate-Count Methods under
Microbiological Examination of Nonsterile Products: Microbial Enumeration Tests 61), inoculating each plate with a small number (not more than 100 cfu) of the appropriate microorganism. Incubate at the specified temperature for not more than the shortest period of time specified in the test. Growth of the microorganism comparable to that previously obtained with a previously tested and approved batch of medium occurs.
Test for Inhibitory Properties, Liquid or Solid Media
Inoculate the appropriate medium with at least 100 cfu of the appropriate microorganism. Incubate at the specified temperature for not less than the longest period of time specified in the test. No growth of the test microorganism occurs.
Test for Indicative Properties
Perform
Surface-Spread Method (see
Plate-Count Methods under
Microbiological Examination of Nonsterile Products: Microbial Enumeration Tests 61), inoculating each plate with a small number (not more than 100 cfu) of the appropriate microorganism. Incubate at the specified temperature for a period of time within the range specified in the test. Colonies are comparable in appearance and indication reactions to those previously obtained with a previously tested and approved batch of medium.
Suitability of the Test Method
For each new product to be tested perform sample preparation as described in the relevant paragraph under Testing of Products. At the time of mixing, add each test strain in the prescribed growth medium. Inoculate the test strains individually. Use a number of microorganisms equivalent to not more than 100 cfu in the inoculated test preparation.
Perform the test as described in the relevant paragraph under Testing of Products using the shortest incubation period prescribed.
The specified microorganisms must be detected with the indication reactions as described under Testing of Products.
For a given product, if the antimicrobial activity with respect to a microorganism for which testing is prescribed cannot be neutralized, then it is to be assumed that the inhibited microorganism will not be present in the product.