Evaluation of Methods for Detection of Coliform Bacteria in Raw Milk1

Abstract

Estimates of populations of “total” coliform bacteria in raw mi1k were quantitatively essentially the same when Violet Red Bile agar incubated at 32 C and Lauryl Sulfate Tryptose Broth incubated at 37 C were used. Qualitatively, LST tended to favor recovery of a greater proportion of Aerobaoter aerogenes and IMViC-irregular types. Of the 46 isolates that produced ropiness, 35 were recovered from LST. Escherichia coli populations, as determined on EC medium incubated at 44.5 C, showed no constant relationship to total coliform population. Summer samples contained not only greater numbers of E. coli but also these organisms constituted a greater proportion of the coliform population.