A selective-differential medium is proposed for the preliminary recognition of Enterobacteriaceae from other Gram-negative bacteria directly on the primary isolation plates. The modified medium, named MCPB, is constituted by a MacConkey agar base with 6-benzoyl-naphthyl-phosphate (as a substrate for the phosphatase activity), and a small amount of dextrose and aniline blue. On the MCPB medium all the enterobacteria and Xanthomonas maltophilia were phosphatase positive and developed red (lactose-negative), or violet (lactose-positive), colonies; all other Gram-negative bacteria formed colourless colonies. Therefore, it is possible to recognize enterobacteria from non-enteric bacteria on the basis of the growth colour and correctly choose the identification kit (either for enterobacteria or for non-enteric bacteria) without the aid of supplemental tests.
A MODIFIED MACCONKEY MEDIUM WHICH ALLOWS THE RECOGNITION OF ENTEROBACTERIACEAE FROM OTHER GRAM-NEGATIVE BACTERIA ON PRIMARY CULTURE PLATES
INGIANNI, ANGELA;
1996-01-01
Abstract
A selective-differential medium is proposed for the preliminary recognition of Enterobacteriaceae from other Gram-negative bacteria directly on the primary isolation plates. The modified medium, named MCPB, is constituted by a MacConkey agar base with 6-benzoyl-naphthyl-phosphate (as a substrate for the phosphatase activity), and a small amount of dextrose and aniline blue. On the MCPB medium all the enterobacteria and Xanthomonas maltophilia were phosphatase positive and developed red (lactose-negative), or violet (lactose-positive), colonies; all other Gram-negative bacteria formed colourless colonies. Therefore, it is possible to recognize enterobacteria from non-enteric bacteria on the basis of the growth colour and correctly choose the identification kit (either for enterobacteria or for non-enteric bacteria) without the aid of supplemental tests.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
