Am I correct in interpreting that indeed any "green" result in the CLED medium is a "mixed result" ie both gram negative and gram positive? And a negative result would not be green.
I have two types of urine dipslide, Uricult Plus and
Dimanco. CLED is green on both of these; the MacConkey agar is red on the Uricult, and orange on the Dimanco.
Growth of bacteria on these agars is not detected by color change, but by the appearance of tiny spots.
Color changes can in certain circumstances can help identify the species of bacteria growing though.
CLED is designed to turn yellow when
lactose positive bacteria are growing on it, and remains green when
lactose negative bacteria are growing.
On MacConkey agar, lactose
positive bacteria colonies turn red or pink on MacConkey agar, whereas
lactose negative bacteria colonies do not change color, forming white colonies.
MacConkey agar will grow both
gram positive and
gram negative bacteria. Whereas MacConkey No.3 agar is a selective medium which will only grow gram negative bacteria. So if you have a urine dipslide with MacConkey No.3 (rather than regular MacConkey), that can help with bacterial identification.
I have been teaching myself a bit about bacterial identification tests. If you happen to have a microscope, then you can see certain identifying features using this: whether the bacteria are
cocci (round shape) or
bacilli (rod shape), and whether they can swim around (
motility).
Another really easy bacterial identification test you can do at home is the
catalase test: just place a few drops of hydrogen peroxide on the bacteria growing on agar, and if it fizzes up, then the bacterium is catalase positive (the catalase in the bacteria causes the hydrogen peroxide to break down releasing oxygen, hence the fizz).
I compiled a table of various easy-to-perform bacterial identification tests, and these can help identify the bacteria you have isolated on the agar. This table is attached as a pdf.
However, I think even for these simple tests, it may not be easy to interpret the results correctly unless you have some experience in bacteriology. But it's fun to perform these tests, as it helps learn about bacteria.