Étude comparative de l'épreuve de la recherche des bactéries " indologènes" et de l'épreuve du dénombrement des bactéries "coliformes " en gélose au desoxycholate pour le controle bactériologique du lait pasteurisé

Abstract - In the higienic testing of milk, several laboratories have com-pared on the one hand the investigation of indologenous bacteria, with, on the other. the enumeration of coliform bacteria, the latter according to two modalities :
a) by cultivation in "Desoxycholate Agar" (Formula B 273 Difco).
b) by cultivation in "Desoxycholate Lactose Agar", (Formula B 420 Difco).
By adopting the respective standards "absence of coliform bacteria in one mL of milk " and " absence of indologenous bacteria in one mL of milk", the application of test " a " penalised 2,5% of the 13.696 samples examined, whereas method " b " penalised 23% of the 6.489 samples analysed.
To replace the search for indologenous bacteria by test " b " (Formula B 420 Difco) without increasing the severity of the test, the following standard must be adopted : " number of coliform bacteria in one mL of milk, less than or equal to 5. "
The autors advocate this new standard