Selective Enrichment and Identification of Salmonella spp. Using Xylose Lysine Deoxycholate and Chromogenic Agar

Abstract

Source: Yang, Z., et al. A High-throughput Platform for the Screening of Salmonella spp./Shigella spp.. J. Vis. Exp. (2018)

This video demonstrates the selective enrichment and identification of Salmonella using xylose lysine deoxycholate (XLD) and chromogenic agar. Selenite broth promotes Salmonella growth, while XLD agar reveals black-centered colonies through hydrogen sulfide production. Chromogenic agar confirms the identity via enzyme-mediated pigment formation, enabling species-level identification.

Protocol

1. Guided Culture

1. Salmonella spp. PCR positive sample
   1. Selective culture in the medium
      1. Add 100 μL of pre-enrichment culture into 5 mL of Selenite Cystine medium in a test tube. Incubate at 36 °C for 18–24 h in an incubator.
   2. Separating culture on a plate
      1. Collect one loop of the culture with a micro-loop and spread it onto an XLD plate or a Salmonella chromogenic agar plate. Incubate at 36 °C for 18-24 h in an incubator.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Selenite Cystine medium	LandBridge	CM225
XLD	LandBridge	CM219
Salmonella chromogenic agar	CHROMagar	SA130
Micro-loop	Weierkang	W511
Incubator	Jinghong	DNP-9082