Subscribe to Germ Theory? Do you mean do I accept it? Yes I do, just as I accept all scientific theories (which doesn't mean what you think it means... it is as close to fact as one can get in science): Gravitational Theory, Theory of Relativity, Evolutionary Theory, and so on and so forth.
Now... science is an iterative, self-correcting, experimental process for understanding the natural world. Koch's postulates have needed revision over time as we have gained more and more understanding of viral and bacterial biology (in the last 130+ years). Here's a recent review article summarizing the current understanding of Koch's postulates:
https://pubmed.ncbi.nlm.nih.gov/31440916/
Hope this is helpful for you. I suggest you put more stock in this than in an internet post on OffGuardian, which "was launched in February 2015 and takes its name from the fact its founders had all been censored on and/or banned from the Guardian’s ‘Comment is Free’ sections."