Gram Stain Kit (Twort Counterstain)

SKU: RRSK45 Categories: , ,

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This stain kit is used to demonstrate Gram Positive and Gram Negative Micro-organisms. The main principle of the technique is the increased thickness, chemical composition and functional integrity of the cell walls of gram positive bacteria, which when they die become gram negative

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100 Test200 Test500 Test1000 Test
Code– 100-200-500-1000
RRSK455 x 50ml5 x 100ml5 x 250ml5 x 500ml


Kit Contains:
Crystal Violet (0.5% Aqueous)
Grams Iodine
Gram Differentiator x 2
Twort Solution A ( 0.2% Neutral Red in IMS)
Twort Solution B (0.2% Fast Green in IMS)

General Information:
Procedure Time : 18 minutes (approximate)
Shelf Life: 3 Years (from date of manufacture)
Storage:    15-25° C.

Gram Positive Organisms:                                               Blue/Black
Gram Negative Organisms:                                              Red/Pink
Nuclei:                                                                                  Red/Pink
Red Blood Cells and most cytoplasmic structures:    Green
Elastic Fibres:                                                                    Black


1. Dewax sections, hydrate through alcohols and rinse in tap water. For smears flood slides with distilled water
2. Stain with crystal violet for 3 minutes (filter before use)
3. Rinse well in distilled water
4. Treat slides with Grams iodine for 3 minutes
5. Wash well in distilled water, drain
6. Differentiate with Grams differentiator until no more colour comes out of the preparation. (1-5 seconds) Rinse off quickly, sections will be straw coloured
7. Immediately wash well in water
8. Mix Twort stain A&B (Twort working solution) immediately before use, as follows: solution A (0.2% neutral red) 9 parts, solution B (0.2% fast green) 1 part, distilled water 30 parts. Stain with the working solution for 3 minutes
9. Wash in water, blot dry and allow to air dry
10. Dehydrate rapidly, clear and mount


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100 Test, 1000 Test, 200 Test, 500 Test