Lysine iron agar slant

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The lysine iron agar slant or LIA slant test is used to distinguish bacteria which are able to decarboxylate lysine and/or produce hydrogen sulfide from those that cannot. This test is particularly useful for distinguishing different Gram-negative bacilli—especially among the Enterobacteriaceae.

Procedure[edit]

The LIA slant is inoculated by stabbing the agar to within 1/4 inch of the butt of the tube and streaking the slant. The slant is then incubated at 35°C for 18–24 hours. The results are scored as follows:

  • purple slant/yellow butt = LSI Negative
  • turbid, purple butt = LSI Positive
  • black precipitate = H2S Positive