Nagler’s reaction is a test for the identification of alpha toxin of Clostridium perfringens. The toxin is lecithinase which hydrolyses the phospholipid lecithin (a component of cell membranes). The activity of the alpha-toxin(lecithinase) can be demonstrated by growth on agar containing egg yolk (as a source of lecithin): an opaque zone representing insoluble diglyceride, becomes evident around colonies of Clostridium perfringens (the Nagler reaction). The activity of alpha-toxin is inhibited by anti-alpha-toxin antibody (generated by vaccination with alpha-toxoid).
Procedure of Nagler Reaction
The picture below represent the opaque zone on the upper right half, around the colonies of clostridium perfringens, as a result of action of lecithinase (alpha toxin) on the lecithin of egg and THIS IS THE NAGLER’S REACTION. while the upper left half does not show this phenomenon because of presence of anti-alpha toxin antibodies. Clostridium sporogenes shows no opaqu zone since it’s lecithenase negative
Nagler’s reaction of Cl. perfringens (lecithinase positive) and Cl. sporogenes (lecithinase negative)
