I am curently in the midst of setting up a microb lab and need help in
interpreting the methods in British Pharmacopoeia which uses the Ph. Eur.
1) Can anyone help me to interprete this sentence: Transfer the quantity of
the contents corresponding to 1g or 1ml of the sample to 100 ml of
enrichment medium....(extracted from BP method 2.6.13 Enterobacteria and
certain other Gram negative bacteria-*Detection of bacteria*) *Does it mean
I need to transfer 0.1ml of the contents(sample)?*I was assuming we are not
actually diluting the sample preparation as we are using broth D in place of
buffered sodium chloride peptone.[eg. For preparation of the sample,when we
dissolve 10g or 10ml of product in 90ml buffer base on a one in ten
dilution,the concentration of sample is 0.1g/ml.When we use broth in place
of the buffer solution, the concentration of sample is 10g/ml.Right?]So,when
I am transfering 0.1ml of the contents into 100ml broth,is the concentration
2) For the *evaluation of Salmonella(10g or ml),*will the concentration of
sample be 10g or ml if we were to transfer 1ml of the enrichment culture(10g
sample that was prepared in 90ml CASO broth) to 10ml of tetrathionate bile
brilliant green broth ?(also from method 2.6.13).It's the same
consept/principle as the above,right?
3) Base on method 2.6.12,under *Preparation of the sample,*what is the
three-class sampling plan all about?Can anyone give me an example on how it
is applied in real situation?
4) May I know the examples medicine of *non-fatty products insoluble in
water* & *fatty products* ?I am not sure how to differentiate them.
5) Under preparation of sample for *fatty products*,which states *'Homogenise
10g or 10ml of the product to be examined with not more than half its weight
of sterile polysorbate 80 or other suitable sterile surface active
agent,....'*How do I interprete the bold sentence?
As for sample related to *non-fatty products insoluble in water,*1g/l of
is added.So,what is the ratio for the diluent - *p80 : buffer* to prepare a
1 in 10 suspension *?*
6) Regarding *reference suspensiopns,*why do we need 10-100cfu/ml?How does
it act as a control of the counting methods and growth promotion
test(sterility testing)?How should I interprete this " *When testing the
membrane filtration method or plate count method, a count of any of the test
organisms differing by not more than a factor of five from the calculated
value from the inoculum is to be obtained.' *Does the factor of five means 1
7) What is Seed lot culture Techniques (sterility testing)?
Hope to hear from all soon.Thank you.
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