TSI contd....

I forgot to mention yesterday that the sugars in TSI are in different quantities, for a reason. Glucose is incorporated at 0.1% while lactose and sucrose are present in 1%. This is so that the orgs are forced to utilise lactose and/or sucrose after glucose is used up.

There is a systematic way of reporting the results. Remember that we are looking at and reading 4 different results, viz, acid or alkaline production in both the butt and slant, gas production and H2S production. We use the abbreviations A for acid and K for alkaline. Acid production is shown by a change in colour from red to yellow, while a change in colour to a deeper red is indicative of alkaline reaction.

All coliforms will give a positive result for glucose utilization, therefore an acid butt.

You must report acid or alkaline production in slant or butt, gas production and H2S production. An exemplar is A/A/no gas/no H2S.

Remember to give me some kind of indication of the order in which you are reporting.

see you!