I had the same question and googled bacteria and parasites and found a bunch of soil Science
articles that say that bacteria are food for parasites. I guess it depends on the type of parasite. I had begun to notice that my symtpoms were worse when taking probiotics/24 hr fermented yogurt, so that is what prompted my google search. I have read it is true from other sources on the internet, but nothing official.
What I've been noticing is that I get a bacterial flare after doing parasite cleanses/meds. So I stop probiotic at the beginning of the cleanse and then restart it afterwards to deal with the flare. There is a lot of rebalancing that happens, I haven't figured it all out yet.