Gram Positive Bacilli
Ehrlich phenomenon is seen in:
The difference between the amount of diphtheria toxin that will exactly neutralize one unit of anti-toxin and that which added to one unit of anti-toxin, will leave one lethal dose free is greater than one lethal dose of toxin; i.e. it is necessary to add more than one lethal dose of toxin to a neutral mixture of toxin and anti-toxin to make the mixture lethal. This is known as Ehrlich phenomenon.