Endo agar is a differential and moderately selective culture medium for the detection and confirmation of coliforms and other enteric microorganisms.
Differential because:
-It uses fuchsin to differentiate between positive lactose-fermenting and lactose non-fermenting bacteria.
-Acetaldehyde production by lactose-fermenting organisms such as E. coli produce characteristic red colonies and a red surrounding area.
- Lactose non-fermenters form colorless, transparent colonies.
Selective:
-The selectivity of Endo Agar is due to the sodium sulfite/basic fuchsin combination which results in the partial suppression of gram-positive micro-organisms