Nagler reaction test is used to identify the gram-positive bacilli clostridium perfringens. Clostridium perfringens have six serotypes from A to F, but only three A, C, and F types cause disease.

Nagler reaction (lecithinase test), principle procedure

Clostridium perfringen causes gas gangrene and food poisioning.

Nagler’s reaction principle

Clostridium perfringe bacteria produce lecithinase, which creates opalescence in the egg yolk media. This opalescence is neutralized by adding the alpha anti-toxin.

Clostridium perfringens nagler reaction procedure microbiology

  1. First of all cover the petridish plate contain yolk egg media with Alpha anti-toxin and allowed to dry.
  2. Inoculate the test organism in the form of streaks.
    1. Note: Take care, start the inoculation from the side there is no alpha anti-toxin and move toward the anti toxin area on petridish.
  3. In the same mannar, some positive and negative organism are also inoculated.
  4. Plate is anaerobically incubated over night at 37 C.
  5. Read the plate. Nagler test postive oragnism (Lacithinase producing) will show opalescence ,but no opalescence where there was anti-toxin. This show that lacithinase synthesisd by the bacteria neutralized the anti-toxin.

What is Positive Control in the lecithinase reaction test?

Clostridium perfringens is used as a positive control organism.

What is Negative control in the nagler’s test?

Clostridium sporogenes can be used as a negative control.

What is the Nagler reaction test in microbiology?

Nagler reaction test is used to identify the clostridium perfringe. Clostridium perfringe produces an alpha-toxin which damages the lecithin of the cell membrane. Alpha anti-toxin is added, which neutralizes the alpha-toxin of clostridium perfringe.

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