Ann: Next Science Investor Presentation May 2019, page-43

I see what you mean. I agree, it's a tad messy. Without wanting to be pedantic, the difference between 80 and 90% is significant ie "about three-quarters vs damn near all of em".

On checking: (my emphasis)
- I see that the page https://www.nextscience.com/the-problem/ says "While approximately 10% of bacteria are free floating, the remaining 90% naturally form colonies called biofilms.55"
- and "Just 10-20% of a wound biofilm is composed of microorganisms with the other 80–90% comprising EPS.8"
- and page https://www.nextscience.com/where-biofilms-exist/ says "According to the US National Institutes of Health, biofilms account for over 80 percent of microbial infections in the human body.18 "

So I think the answer is, they have taken the liberty of interpreting references 55, 8 and 18, as basis for a fair call in the prospectus of 90%. Reasonable, I suppose.