(X) Phages versus (Y) Bacteria ( to see Phage Therapy Theory)
Before.....
A1) a table ( matrix) is compiled in the following way:
-the results obtained with all present Bacteria that are tested with each Phage are written in each respective column.
-the results obtained with all present Phages that are tested with each Bacterium are written in each respective row.
-when one Phage lyses the bacterial lawn completely by the Lower Titer (the number of PFUs in a given volume of sample gives the viable phage concentration or titer) is assigned the value=1.
-when one Phage does not lyse the bacterial lawn completely by the Higher Titer is assigned the value=0.
A2) for each phage to add up the results in the respective column.
A3) for each bacterium to add up the results in the respective row.
For one bacterial strain the total from the respective row is the Limit Value (LV) .
Each bacterial strain must be lysed by a minimum of 2 phages or more (it is the respective Minimum Limit Value ,LV) !!!!!!
The minimum of 2 lysing phages for each bacterial strain is obliged .
LV=2, if the minimum is 2 lysing phages.
LV=3, if the minimum is 3 lysing phages.
LV=n, if the minimum is n lysing phages.
A4) the sum of totals for column and the sum of totals for row is equal to
Real Total Limit Value (RTLV)= Sum of the totals for column or sum of the totals for row (it means: Several ( not all) Phages lyse several ( not all) Bacterial strains ).
A5)Max. Theoretic Limit Value (MTLV)= X*Y (it means: all Phages lyse all Bacteria).
In this example we have tested 8 Phages against 50 bacterial strains and the results are simulated .
X and Y are choosed as required each time.
If X= 8 and Y = 50
In that case:
MTLV= 400
RTLV= 230
RTLV%= (230/400) *100=57,5
The Phage Cocktail Chances increase if the RTLV converges to the MTLV.
Example:
MTLV 1= 400
RTLV1= 230
RTLV%1= 57,5 (Several ( not all) Phages lyse several ( not all) Bacterial strains )
But if we have:
MTLV2= 400
RTLV2= 300
RTLV%2= 75 (Several ( not all) Phages lyse several ( not all) Bacterial strains )
Consequently RTLV%2> RTLV%1 and the chances are increased.
B1) the bacterial strain/strains having the lower total value for row ( LV=2) is/are selected.
B2) the phage having the higher total value for column (1°) is selected.
B3) each 0 value for this Phage must be neutralized by 1 value belonging to the second phage with a high value ( 2°) or to the third Phage ( 3°) or to the fourth phage and so on.
B4) The new RTLV is calculated and also the mutation rate value for each bacterial strain (bacteriophage-resistant mutant colonies).The relationship between mutation frequency and the rate at which mutations occur is uncertain.
B5) If one Bacterial strain has the LV <2 another phage is selected in the table up to the value of LV is equal at 2 or more.
B6) the Phage Cocktail is ready and very definite when the useless Phages are removed. In this example the Phage Cocktail contains 7 Phages and is capable to lyse all Bacterial strains.
