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Enterobacteriaceae 2
Testing Media
Media Name | Characteristics of Media |
---|---|
Hektoen Agar (HE) | Selective for Enteric pathogens Contains bile salts & dyes - cause the slow growth of nonpathogenic GI organisms while encouraging the growth of pathogens Salmonella and Shigella HE media - differential for lactose fermentation & H2S production |
XLD agar – Xylose, Lysine, and Desoxycholate agar | Selective & Differential for Salmonella and Shigella fermenters – appear yellow = acid NonFermenters = appear red due to phenol red indicator in alkaline environment H2S producers will have black centers (Salmonella) Desoxy. salt = inhibit Gram + |
SS – Salmonella Shigella agar | Inhibits non-enteric pathogens by brilliant green dye and bile salts Neutral red is the indicator Salmonella and Shigella will be clear Lactose fermenters will be pink/red H2S production is shown as black |
GN or Gram Negative Broth | Selective broth for Gram – growth Contains bile salts = inhibit growth of Gram + & the early multiplication of Gram – non-pathogenic enterics Broth must be subcultured in 6-8 hours / Selenite broth – an alternative to GN broth |
CIN Agar - (Cefsulodin-irgasan-novobiocin) media | Highly selective medium to isolate Y. enterocolitica Selective chemical agents, antibiotics, dyes, basal medium. highly selective against growth of E. coli, K pneumoniae, P. mirabilis, P. aeruginosa, S. typhimurium, S. sonnei and S. faecalis. |
Selective agar -Sorbitol-MacConkey | Indicates sorbitol fermentation as opposed to lactose. EHEC - E.coli O157:H7 is a nonfermenter of sorbitol and colonies will be clear (negative) Other E. coli do ferment sorbitol, and the colonies will be pink (positive) |