Bacteria reduction is generally represented in log scale varying from 1 log reduction onward upward 9 log. However, this only represent 99.99999... reduction.
So how to represent 100 % bacteria reduction in log form.
Because after treatment I did not find any colony as compared to control sample.
Please help. Many thanks.
100% reduction has no exact definition as a log reduction, since log(0) is undefined mathematically. The best you can say is that the reduction is greater than log (control cfu), where "control cfu" is the colony count for your control sample. So, if your control sample had 100 cfu, and zero cfu for the test, then your reduction is "greater than log(100)" or "> 2 log".
William A. Anderson
Thank you very much for your helpful answer.
In the above mentioned scenario would it be advisable to represent the results in percentage reduction rather than log scale whereby 0% is no bacteria reduction and 100% being total elimination.
As William A. Anderson says you cannot. But be clear, how can you be sure you have 100% elimination as you are suggesting? I doubt you can ever be certain, due to sampling issues and the analytical sensitivity of the assay used in your experiment, e.g. if you are plating 0.1 ml on an agar plate, then then you cannot reliably (P=0.95) detected less than 30 CFU/ml. Your apparent zero may not be zero, so IMHO it always better to say that you reduced numbers to less than the detection limit of the test or by more than 2 log etc....
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