What is the standard procedure to do TBC for a fecal sample? Which broth is better for inoculation BHI/Nutrient broth or Tryptose soy broth or any other? And upto what dilution should we use?
Please check the link below:
http://www.sciencedirect.com/science/article/pii/S0308814613006237
Total bacterial count from faecal sample can be done using the Normal Saline 0.85%. In the 1:9 ratio, homogenize the sample and then perform the serial dilution from second tube on wards. Transfer 1 ml to each broth till last broth tube. Till what fold dilution you should do that depends on the number of bacteria which you will know once you perform the test and then you will have an idea about the maximum dilution. To my experience up-to 7 fold dilution is sufficient, where you will be able to count the bacterial colonies easily. From each dilution you need to transfer 100 micro liter in duplicate plates of Plate Count Agar or the agar of your choice as per your target organism. The plating can be done either through spread plate method, where you will need a sterile spreader to spread the suspension or pour plate method where the suspension is mixed thoroughly by shaking the plates circular motion. Incubate it at 37 degree which is usually for 24-48 hours (time may vary as per the target organism) and post incubation you may count the colonies.
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