About CMT
Description and principle of the test
CMT is available as a single test which can be used for analyzing
milk samples on a small scale at the farm level and
in outlying or satellite testing labs and as a multiple test microplate
for large scale analysis at central receiving stations, milk processing plants
or quality
control laboratories. CMT can be used for the detection of antimicrobial
residues in milk from cows, goats and sheep including
raw
milk, heat-treated milk and
milk powder.
The
test is supplied in individual tubes and multi-well
microplates filled with an agar medium. The agar is pre-seeded
with
spores of Bacillus stearothermophilus
var. calidolactis and incorporates a fermentable sugar: glucose and
a pH indicator: Bromocresol Purple. The test is ready to
use with no necessity
to activate the product by adding a nutrient tablet. The operator simply
pipets 100µl of milk sample directly onto the surface of the agar
and then incubates the test at 64°C in a water bath, incubator
or heater block for a prescribed length of time. The milk quickly diffuses
throughout
the agar medium. If there are no antimicrobial substances in the milk
sample or the concentration is lower then the limits of detection the
Bacillus
spores germinate, grow and metabolize the sugar. The acid produced
from
the fermentation of glucose changes the color of the indicator Bromocresol
Purple in the medium to a yellow color. Alternatively, if antimicrobial
substances are present in the milk sample then germination and growth
of the Bacillus spores is inhibited. This means there is no fermentation
of
glucose, no acid production and therefore the Bromocresol Purple indicator
in the medium remains a purple color.