Poisson Frequencies Calculator

∞ generated and posted on 2022.05.22 ∞

Based on actual Multiplicity of infection (MOIactual), we can predict the frequencies not only of unadsorbed bacteria, singly adsorbed bacteria, and multiply adsorbed bacteria, but also the frequencies of the latter among only adsorbed bacteria.

Please cite as:

Stephen T. Abedon
Poisson Frequencies Calculator.

Click here for calculator or see immediately below for further explanation and discussion.

Phages are considered to adsorb especially isolated, planktonic bacteria in frequencies described by Poisson distributions. These are similar to Normal distributions except that the values found on the x axis are both discrete (i.e., integers only) and don't include negative numbers.

If we know the ratio of adsorbed phages to adsorbable bacteria, so-called MOIactual, then we can calculate the Poisson distributions for that multiplicity of infection.

Thus we will have some expected frequency of bacteria that are not phage adsorbed, some frequency that are adsorbed by only a single phage, some frequency that are adsorbed by exactly two phages, and so on.

Relevant to analyses of phage biology, we can also consider what fraction of phage-adsorbed bacteria have been adsorbed only a single phage or more than one phage, etc.

Starting with a value for MOIactual, this calculator provides various such frequencies, both per adsorbable bacterium and per actually adsorbed bacterium.


For further discussion, see:

Abedon, S.T. (2022). Further Considerations on How to Improve Phage Therapy Experimentation, Practice, and Reporting: pharmacodynamic perspectives. Phage 3:98-111.

Abedon, S.T. (2021). Multiplicity of infection. Reference Module in Life Sciences, Elsevier

Abedon, S. T. and Katsaounis, T. I. (2018). Basic Bacteriophage Mathematics. Advances in Applied Microbiology (this is for the Clokie, Kropinski, and Lavigne protocols book, third volume).

See also the Multiplicity of Infection Calculator.

The above number is the ratio of
adsorbed phages to adsorbable bacteria,
e.g., such as 1:1 as indicated by a '1'.