Search Thermo Fisher Scientific
Search Thermo Fisher Scientific
Use Gram-Sure reagent-impregnated disk to rapidly differentiate aerobic, Gram-negative, and Gram-positive rods or coccobacilli.
Differentiate aerobic, Gram-negative and Gram-positive rods or coccobacilli with Thermo Scientific™ Remel™ Gram-Sure reagent-impregnated disks. This is a rapid disk test performed using fluorescent technology. The Gram stain is generally the first step in the identification of bacteria and decides subsequent identification procedures. The tendency of some Gram-positive rods to appear Gram-variable or Gram-negative, especially members of the genera Bacillus, Erysipelothrix, Lactobacillus, and Listeria, may often result in misclassification.
Differentiate aerobic, Gram-negative and Gram-positive rods or coccobacilli with Gram-Sure Disks.
The cell walls of Gram-negative organisms contain aminopeptidase, which is detected by hydrolysis of L-alanine-7-amido-4-methylcoumarin from a non-fluorescent substrate to a fluorescent compound. In 1976, Cerney reported using L-alanine-4-nitroanilide to detect cell-wall aminopeptidase, which correlated with Gram negativity1. In 1990, Manafi and Kneifel evaluated various chromogenic and fluorogenic substrates for the ability to differentiate Gram-positive and Gram-negative bacteria2. They recommended using the fluorogenic substrate L-alanine-7-amido-4-methylcoumarin due to its higher test sensitivity and pronounced blue fluorescence indicating a positive reaction.
Gram-Sure disk contains the reactive ingredient L-alanine-7-amido-4-methylcoumarin which exhibits pronounced blue fluorescence and increased test sensitivity. Aerobic, Gram-negative rods and coccobacilli show a bright blue fluorescence, whereas Gram-positive rods and coccobacilli do not display any fluorescence.
This test is used to serve as an adjunct to the traditional Gram stain method and not a replacement.