Mode of Action
The combination of various peptones, extracts, salts, and buffer substances enable very good growth of Listeria. The selectivity is due to the antiproliferative substances nalidixic acid and acriflavine hydrochloride.
The two-stage enrichment method has demonstrated its value especially with sample materials (meat and meat products) that are characterized by a high level of accompanying flora.
Typical Composition (g/litre)
UVM-I Broth Tryptose 10.0; meat extract 5.0; yeast extract 5.0; sodium chloride 20.0; disodium hydrogenphosphate 12.0; potassium dihydrogen phosphate 1.35; esculin 1.0; nalidixic acid 20.0 mg; acriflavine hydrochloride 12.0 mg.
Composition identical to UVM-I Broth. In addition, dissolve 13mg acriflavine hydrochloride (= 1 vial of UVM-II Supplement) in 10 ml sterile, distilled water and add to UVM-I Broth which has been previously sterilized and cooled below 50 °C.
Suspend 54,4 g in 1 litre of demin. water and autoclave (15 minat 121 °C).
pH: 7.2 ± 0.2 at 25 °C.
The medium is clear to opalescent and yellowish-brown.
1st Enrichment Step: Inoculate the UVM-I broth with sample material (generally 25 g sample material per 225 ml broth) and incubate at 30 °C for 24 hours.
2st Enrichment Step: Inoculate 0.1 ml of UVM-I Broth into 10 ml of UVM-II broth and incubate at 30 °C for further 24 hours aerobically.
Approximately 0.1 ml of the UVM-II Broth is then smeared on the surface of a Listeria-selective agar (e.g. PALCAM Agar,or Oxford agar, in such a way to obtain well isolated single colonies