Primary enrichment broth for the isolation of Listeria spp. formulated according to ISO 11290. The
selective components acriflavine and nalidixic acid are blended into the base powder and the ferric ammonium citrate is added to the tempered broth after sterilization.
Half Fraser (Demi-Fraser) Broth (ISO), NCM0001 was developed to give improved results for the isolation
of Listeria spp. with both traditional and ELISA methods. As with the sister product, Fraser Broth,
NCM0050 the selective components acriflavine and nalidixic acid are blended into the base powder and
the Ferric Ammonium Citrate is added to the tempered broth after autoclaving. This format has been
shown to give improved selectivity with pure cultures and food samples. Furthermore, more stable ELISA
results are seen, resulting in fewer false positive results when the ferric ammonium citrate is omitted from
the complete media.
Developed as a modification of UVM medium (NCM0012) and made according to ISO 11290, Fraser
Broth is a secondary enrichment broth for the isolation of Listeria spp. and is similar to Palcam Broth
(NCM0049) in that it contains esculin to indicate the presence of a potential Listeria isolate. It also
contains lithium chloride in an attempt to suppress the growth of Enterococci in the medium (as does
Palcam). Listeria spp. hydrolyze the esculin to form esculetin, which reacts with the ferric ammonium
citrate in resulting in a black precipitate and a visible positive reaction. However, Enterococci can also
perform this reaction so further plating is required onto an isolation medium such as Harlequin Listeria
Chromogenic Agar according to Ottaviani & Agosti (NCM1004).
Note: Acriflavine and Nalidixic Acid in NCM0001 are half-strength of Fraser Broth NCM0050.
Peptone Mixture 15.0 g/L
Yeast Extract 5.0 g/L
Esculin 1.0 g/L
Disodium Hydrogen Phosphate 9.6 g/L*
Potassium Dihydrogen Phosphate 1.35 g/L
Sodium Chloride 20.0 g/L
Lithium Chloride 3.0 g/L
Acriflavine 0.0125 g/L
Nalidixic Acid 0.01 g/L
pH: 7.2 ± 0.2 at 25°C
*equivalent to Disodium Hydrogen Phosphate Dihydrate 12.0 g/L
Formula may be adjusted and/or supplemented as required to meet performance specifications.
Ferric Ammonium Citrate Supplement (X211) or Fraser Broth Base Supplement (7984) may be used